taxonID	type	description	language	source
432A0A535276FFB5FC93ED94FEC9FDA2.taxon	diagnosis	Diagnosis. (see Grube, 1840) Remarks. Dendrochirotida are suspension-feeding sea cucumbers found worldwide, more common in shallower waters though extending to abyssal depths. Some species burrow in soft sediments; others attach to hard surfaces and extend their branched tentacles into the water column to feed. This order comprises 11 currently accepted families, five of which are represented in Australia: Cucumariidae, Phyllophoridae, Psolidae, Sclerodactylidae and Ypsilothuriidae, with others found in Australian Antarctic waters. While it was anticipated that the shallower depths of Muirfield Seamount would provide more suitable bathymetric range for this order, surprisingly only one deep-sea species from one family was represented in the IOT material.	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535277FFB5FF29E81FFC7AFAFC.taxon	diagnosis	Diagnosis (amended from O’Loughlin et al., 2015). Mid-body sub-spherical, tapered non-retractile oral and anal ends, usually upturned; calcareous ring cucumariid-like, lacking posterior prolongations; tentacles ten, digitiform, unequal in size; tube feet slender, restricted to ambulacra, can be discrete, sparse, or absent; body invested with large imbricating scales that are single-layered perforated plates, each scale with predominantly one tall spine typically arising near plate margin. Remarks. Echinocucumis has previously been recorded from the Atlantic, Pacific, Indian, and Southern Oceans including Antarctica with eight currently accepted species. Only one species – E. ampla – was found in the IOT, previously recorded from the Southern Ocean and off the eastern coast of Australia. Diagnosis from O’Loughlin et al. (2015) amended to include discrete tube feet and to allow for variation in spine placement on ossicles as not all are marginal. Echinocucumis ampla O’Loughlin and Skarbnik-López in O’Loughlin et al., 2015 Figure 2 a – f, Appendix 1, Table S 1.	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535277FFB5FF29E81FFC7AFAFC.taxon	description	119, 146. Material examined. NMV F 296861 (1) [IN 2021 V 04 031]; NMV F 308161 (1) [IN 2022 V 08 105]. Diagnosis of IOT material. Small, white, u-shaped species with prominent belly mid-body. Anterior variably upturned and slightly tapered to a rounded oral end, posterior tapered to upturned tail. Skin thin, brittle, parchment like and often “ prickly ”, particularly on ventral surface, due to the complete cover of imbricating spined scales. Tentacles retracted here but typically ten digitiform of irregular length and supported by curved rod ossicles. Ventrolateral tube feet in sparse, paired rows (fig. 2 c). Body wall ossicles were broken in these specimens but show single-layered perforated plates with a single large composite spire greater than 200 μm high and typically marginal sometimes central on plates (fig. 2 d, e). Broken solid plates (fig. 2 f) were also observed in perianal ossicle samples. Preserved specimens from IOT up to ~ 25 mm long (lateral width, tentacles withdrawn) and 10 mm high mid-body (NMV F 308161). Remarks. Presence perianally of solid plates was considered a diagnostic character for this species (Mark O’Loughlin, pers comm., 2018). They were seen in this material (fig. 2 f) but without the occasional small, spaced perforations expected. The original species description does not include tube feet for the larger (65 mm long) specimen, but the possibility of their presence was raised in “ Remarks ” (O’Loughlin et al. 2015). In specimens from the eastern Australian abyss subsequently identified as E. ampla by O’Loughlin, tube feet were evident in smaller specimens, but rarely in larger specimens (Mark O’Loughlin, pers comm., 2018). Here we report the presence of ventrolateral tube feet, clearly observed in these small IOT specimens when viewed under a microscope (fig. 2 c). Only 16 S sequence data is available for this species (Table S 3). It was recovered in a clade representing the family Ypsilothuriidae. Distribution. Southern Ocean (O’Loughlin et al., 2015), South Pacific (eastern coast of Australia, see below), and Indian Ocean (Australian IOT, this work). Full bathymetric range. 557 – 4139 m (IOT 2189 – 2435 m). Type locality. Southern Ocean, southern Kerguelen Plateau northeast of Heard Island, 708 m. This species was not recorded from Australia in AFD prior to January 2024, but was recorded from off the eastern coast in ALA (January 2024) from Freycinet in Tasmania to the Coral Sea in Queensland at 1006 – 4139 m. This IOT material represents a geographic range extension for the species. References. AFD (2023), ALA (2024), O’Loughlin et al. (2015), O’Loughlin (notes and personal correspondence, 2018), Rowe et al. (2017).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535277FFB5FC8BEED6FAD7F8CC.taxon	diagnosis	Diagnosis. (see Théel, 1882) Remarks. The Elasipodida are a deep-sea order of sea cucumbers lacking respiratory trees. They are typically gelatinous, have peltate feeding tentacles, and have tube feet adapted for walking along the seafloor or fused for swimming. Unfortunately, the often-soft outer skin is easily damaged during collection, and their watery bodies also make preservation difficult. The order comprises four currently accepted families: Elpidiidae, Laetmogonidae, Pelagothuriidae and Psychropotidae, all of which are represented in Australian waters. As expected for this dominant deep-sea order, all four families were also represented in the IOT material. Hansen (1975) reviewed the Elasipodida comprehensively in the Galathea Report, and despite subsequent revisions for specific groups, this remains one of the best overall sources for descriptions and keys for the order.	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535277FFB5FF29E974FECFFC84.taxon	diagnosis	Diagnosis. (see Heding, 1942) Remarks. Previously found in the deep sea off the south and northeastern and northwest coasts of Australia, this family comprises U-shaped burrowing species with a covering of spired ossicles. Of the three currently accepted genera, two (Echinocucumis and Ypsilothuria) were previously recorded for Australia.	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535271FFB3FF29EBB6FEEAFD17.taxon	diagnosis	Diagnosis (following Hansen, 1975). Tentacles 10 – 12. Ventrolateral tube feet large, well-spaced, and usually few. Midventral tube feet absent. Calcareous ring consisting of five star-shaped pieces. See Hansen (1975) for further comments. Remarks. The Elpidiidae are a cosmopolitan deep-sea family, with some species known to form dense benthic aggregations (Gutt and Piepenburg, 1991). Recorded in Australia from off the east and west coasts and in the Great Australian Bight. Of the 13 currently accepted genera, seven are known from Australia: Achlyonice, Amperima, Elpidia, Kolga, Peniagone, Psychroplanes and Scotoplanes, with additional genera found in Australian Antarctic waters (ALA, 2024; WoRMS, 2024). IOTmaterialincludesexamplesfrom Peniagone, Psychroplanes and Scotoplanes.	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535271FFB3FF29EEA0FA7DF9FA.taxon	materials_examined	Material examined. NMV F 308267 * (7) [IN 2022 V 08 145]. Other material. Peniagone azorica Marenzeller von, 1892 – off eastern Australia, NMV F 241035 [IN 2017 V 03 090 110]; NMV F 240855 [IN 2017 V 03 032 143] (identified by Mark O’Loughlin, 2018). Diagnosis of IOT material. Damaged, fragile specimens. Elongate, dorsally raised and convex but ventrally slightly rounded to flattened. Anterior end downturned with ventral mouth on neck tube (not visible in photo) and only four flaccid tentacles remaining. Anus dorsal and terminal. Pink to orange before preservation, with a fragile, translucent brim (<10 mm wide) around the entire animal, extending to form a wider anterior velum of five fused papillae. Central two anterior papillae are longer, with all fused for most of their length. Tube feet where visible appear restricted to posterior third of the body, and almost fully embedded in the brim. Preserved specimens (ethanol) are grey and spongey with chalky skin, brim and fused velum either lost or reduced to stringy pieces and approximately six previously embedded larger tube feet appearing free, with only the series of minute posterior tube feet remaining fused. Ossicles in body wall include larger irregular spinous crosses (fig. 3 b – d), with four or more flat to slightly curved arms (up to 455 μm long), and Peniagone - type crosses with arms and apophyses, both with smooth central beams. Peniagone - type crosses mostly two types, some with four arms and 2 – 4 (typically 4) high apophyses curved inwards (fig. 3 g – h), others (more common in ventral wall) with irregular arms curved out and shorter thick, spinous apophyses (fig. 3 f, i). Both types have spines (serrations) on both arms and apophyses. Tentacles with same and spinous supporting rods. Most complete preserved specimen from IOT ~ 105 mm long, 15 mm wide and 15 mm high. Likely same specimen as shipboard image which was ~ 145 mm long and 45 mm wide before preservation (fig. 3 a). Remarks. Ossicles combined with body shape and tentacles closest to original type description of P. azorica Marenzeller von, 1892 from the North Atlantic, and subsequently descriptions by Hansen (1975). Identified as Peniagone cf azorica here as whole-body brim including completely fused anterior velum and tube feet embedded in a posterior brim (as seen in IOT specimens) does not match the bipartite velum and free tube feet bordering entire ventral sole of the original description, Hansen’s (1975) descriptions, or those described more recently from the mid-Atlantic (Rogacheva et al., 2013). Ossicles, colour and morphology of IOT specimens match at least two of the six specimens Mark O’Loughlin identified as P. azorica Marenzeller von, 1892 from Australian eastern abyssal stations, which had a brim and fused velum in shipboard images but lost these after preservation (NMV Catalogue, 2018). Distribution. These specimen lots: Indian Ocean, Australian IOT, Cocos (Keeling) Islands Territory, Cocos (Keeling) Stn., 3002 – 3078 m; Two comparative specimens noted above: off eastern Australia in East Gippsland Marine Park and off Byron Bay, 2562 – 3853 m. Full bathymetric range. 2562 – 3853 m. References. Gebruk et al. (2014), Hansen (1975), Hansson et al. (2001), Marenzeller von (1892), Rogacheva et al. (2013), Kremenetskaia née Rogacheva (pers comm., 2023), Théel (1882)	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535271FFB3FF29E989FE3FFA6D.taxon	diagnosis	Diagnosis. (amended from Hansen, 1975). Dorsal papillae anteriorly placed, usually forming a velum. Ossicles primary crosses or cross-shaped bodies with variable arms and apophyses arising from a central stem. Calcareous ring consisting of five isolated pieces, each having a varying number of arms. Remarks. Benthic and swimming genus, worldwide except for theArctic with high species diversity in the Pacific and Antarctic (Gebruk et al., 2014). Peniagone ossicles are of an adapted cross shape, with arms always arising from a central beam or stem. Of the 35 currently accepted species of Peniagone, five have been previously recorded for Australia: P. affinis, P. azorica, P. challengeri, P. vignoni, and P. vitrea (ALA, 2024; WoRMS, 2024). Two new records for Australia of known species are recorded here: P. coccinea and P. purpurea. Eighteen lots of Peniagone were recorded from the IOT voyages at depths of 2156 – 5414 m, with 12 lots further identified to OTU species level as follows: Peniagone cf azorica (1 lot), Peniagone cf challengeri (1 lot), P. coccinea (4 lots), P. purpurea (1 lot), P. vitrea (3 lots), Peniagone sp. MoV. 7320 (1 lot), Peniagone sp. MoV. 7321 (1 lot). Genus diagnosis was amended from Hansen (1975) to note apophyses and central stem. Peniagone is a well-supported, monophyletic genus in both the COI and 16 S phylogenies (fig. S 1). However, more molecular data is needed to resolve species-level relationships.	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535271FFB1FC8BED2CFBF4F8CD.taxon	description	Figure 4 a, b, Appendix 1, Table S 1 Material examined. NMV F 308151 (1) [IN 2022 V 08 105]. Diagnosis of IOT material. Single small, elongate specimen, 32 mm long, 10 mm wide and 5 mm high (preserved). Light pink and soft before preservation, light grey to white and firm once preserved (ethanol). Quite damaged, outer skin looks stripped and “ fluffy ” and preserved specimen was stripped of most appendages. Anterior end downturned with ventral tentacle crown. Two long tapered dorsal anterior lobes visible on damaged velum. Tube feet where visible on preserved specimen were free and restricted to posterior section, though live photo shows a potential brim of partly fused appendages. Posterior mid-terminal incision in preserved specimen, but not obvious in shipboard photo so may be an artifact. Minimal ossicles but all Peniagone - type crosses with four long spinous arms, long bare central stem, and four short and spinous apophyses. Remarks. Identified here as closest to Peniagone challengeri Théel, 1882 based on the morphology described, particularly the ossicles (which match the illustration for the type specimen of P. challengeri in Théel, 1882), bifid velum, posterior tube feet and elongate form, but too damaged to identify further than Peniagone cf challengeri. Distribution. This specimen lot only: Indian Ocean, Australian IOT, Christmas Island Territory, Balthazar Seamount Stn., 2298 – 2435 m. Full bathymetric range. 2298 – 2435 m. References. AFD (2024), ALA (2024), Cross et al. (2009), Hansen (1975), O’Loughlin (1998), Rowe et al. (2017), Théel (1882). Peniagone coccinea Rogacheva and Gebruk in Rogacheva et al., 2013	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535271FFB1FC8BED2CFBF4F8CD.taxon	materials_examined	Material examined. NMV F 296857 * (1) [IN 2021 V 04 028]; NMV F 308183 (1), NMV F 308188 * (1) and NMV F 308189 (2) [IN 2022 V 08 115]. Diagnosis of IOT material. Bright pink to red and gelatinous with semitransparent skin (live), cream to grey with pink tinge (preserved, ethanol). Body form elongate, raised dorsally and broadening towards the posterior end. Most complete preserved specimen up to ~ 70 mm long, 20 mm high and 20 mm wide (NMV F 308183, fig. 5 a). Anterior dorsal velum with two pairs of long papillae fused at the base on each side (central ones longer). Mouth downturned on short neck tube with flaccid tentacles extended, only six remaining on the most complete specimen. Posterior with a brim of small, fused tube feet and dorsal anus. Skin is soft and easily damaged. Ossicles of body wall are flat, irregular, variably spinous crosses (fig. 5 b – f), and two kinds of Peniagone - type crosses, all with smooth (or minutely spinous) central beams, some with irregular extra branches. One version of Peniagone - type cross with mostly wide but inward-curving spinous arms and four (3 – 4) shorter straight, almost vertical spinous apophyses (fig. 5 i – k). Other type with mostly four outward-curving arms, quite irregular in length and shape and often strongly spinous at ends, with mostly four short, thick spinous apophyses (fig. 5 l – o). Tentacles, tube feet, velum (and occasionally body wall) with additional irregular spinous rods, straight to curved (fig. 5 g, h). Remarks. Colour and brim like Peniagone cf azorica above, but ossicles are distinctive and have the more “ irregular ” form of P. coccinea Rogacheva and Gebruk in Rogacheva et al., 2013. Distribution. North Atlantic, Indian Ocean (Australian IOT). Full bathymetric range. 2600 – 2974 m (IOT 2760 – 2974 m). Type locality. North Atlantic, Mid-Atlantic Ridge south of the Charlie Gibbs Fracture Zone, 2600 – 2750 m. This species not previously recorded from Australia in AFD or ALA (January 2024). This IOT material represents a geographic range extension for the species and a small increase in depth range. References. AFD (2024), ALA (2024), Gebruk et al. (2014), Rogacheva et al. (2013).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A53527DFFBFFF29EBB6FE39F92C.taxon	description	2021: 14, fig. 9. Elpidia ambigua. — Théel, 1882: 27 – 28, pl. 33: 6. Peniagone lacinora. — Agatep, 1967: 53 – 55, pl. 3: 1 – 9. Peniagone vexillum. — Perrier, 1902: 429, pls. 12: 6, 19: 24 – 25.? Peniagone ferruginea. — Grieg, 1921: 7 – 8, fig. 3, pl. 1: 4 – 6. Material examined. NMV F 296841 * (1) [IN 2021 V 04 007]. Diagnosis of IOT material. Single partial specimen, light pink to mauve, soft, gelatinous, and partially transparent with thin skin. Purple to grey once preserved and in two pieces, each ~ 20 mm long. Severely damaged, single podia but no other external features remaining, skin wall not rough. Body wall ossicles typically Peniagone - type crosses with smooth (or minutely spinous) central beam, four widely spread long spinous arms and four shorter spinous apophyses directed vertically or outwards (fig. 6 b – e). Some with longer and more curved arms (fig. 6 f, g). Other crosses lower with arms slightly curved to almost horizontal and short, thick apophyses (fig. 6 h, i). Arms up to 320 μm long in these samples. Tentacles with crosses and supporting rods. Remarks. Identification as P. purpurea rather than other Peniagone species based on limited specimen morphology and colour, combined with ossicles being closest to the type description and illustrations in Théel (1882) (excluding the rough skin from crowded ossicles). Note that Hansen (1975) describes only primary crosses with a well-developed stem and four long apophyses for P. purpurea, but IOT material is a closer match to the original illustrations in Théel, with mix of ossicles with shorter or longer apophyses. Differs specifically from Peniagone vitrea by mauve colour, more gelatinous skin, and different combination of ossicles as shown in fig. 6 cf. fig. 7. Distribution. Antarctic, Atlantic, West Pacific, Indian Ocean: southern Indian Ocean (near Crozet), and Australian IOT. Full bathymetric range. 2800 – 5610 m (IOT 3200 – 3345 m). Type locality. southern Indian Ocean, west of Alfred Faure (Crozet Archipelago), 3560 m. This species not previously recorded from Australia in AFD or ALA (January 2024). This IOT material represents a geographic range extension for the species. References. AFD (2024), ALA (2024), Cross et al. (2009), Gebruk et al. (2014), Théel (1882).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A53527DFFBFFF29EDE6FB4AF8CD.taxon	materials_examined	Material examined. NMV F 308222 * (1) [IN 2022 V 08 120]; NMV F 308226 (1) [IN 2022 V 08 122]; NMV F 308268 (1) [IN 2022 V 08 145]. Diagnosis of IOT material. Large glassy-white to cream specimens up to 95 mm long, 20 mm wide and 20 mm high (NMV F 308222 preserved). Typical Peniagone shape, strongly raised anterior to mid-dorsally then flattening posteriorly, slightly convex to flattened ventrally. Broad and short anterior velum of four papillae, fused for most of their length, with two central papillae a little longer and freer. Mouth on distinct neck tube curved at an acute angle ventrally and with extended flaccid tentacles, only five remaining in the most complete specimen (NMV F 308222, fig. 7 a). Tube feet also mostly stripped from these specimens but all free and restricted to posterior third. Skin feels very rough due to crowded ossicles that are visible to the eye. Typically, Peniagone - type crosses with short, smooth central beam, four straight to slightly curved spinous arms, and 2 – 4 straight, spinous apophyses (fig. 7 g – i). Arms wide, apophyses more vertical and nearly as long as arms where complete. Velum ossicles similar. Tube feet ossicles variably similar tall crosses, to lower versions with wider arms and shorter apophyses. Tentacle ossicles mostly irregular smooth crosses without (or with very reduced) apophyses and straight to slightly or strongly curved rods, variably smooth, spinous, or branching (fig. 7 d – f). Remarks. Despite extensive damage the external morphology available is congruent with the type description for P. vitrea Théel, 1882. Body wall ossicles also fit description, but some IOT ossicle arms were up to 417 μm long, much longer than the type ossicle arms noted as 160 μm. Tentacle ossicles for IOT included curved rods in addition to the straight rods and basic crosses mentioned for types. Distribution. Widespread in Pacific Ocean, including Clarion-Clipperton Zone (CCZ), Kuril – Kamchatka Trench, off southern Chile, Gulf of Panama; off southern and eastern Australia; Antarctic; Indian Ocean (Australian IOT). Full bathymetric range. ~ 1300 – 4990 m (IOT 3002 – 4990 m). Type locality. off southern Chile, 2652 m. This species previously recorded from Nowra to Point Hicks in AFD (January 2024), and from eastern coast of Australia (off southern Tasmania to northern NSW and Great Australian Bight off South Australia at depths of 1360 – 4750 m) in ALA (January 2024). This IOT material represents a geographic range extension as the first record of the species from the Indian Ocean, and a potential bathymetric range extension with this previously reported as ~ 1300 – 4500 m in Kremenetskaia et al. (2021). References. AFD (2024), ALA (2024), Bribiesca-Contreras et al. (2022), Clark (1920), Hansen (1975), Kremenetskaia et al. (2021), Ludwig (1894), Théel (1882).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535278FFB9FC93ED76FDB4FDD1.taxon	diagnosis	Diagnosis. (translated from Gebruk, 1988). Body ovoid, length to width ratio ~ 2: 1. Dorsally convex, body height equal to or exceeding body width. Dorsal ambulacral appendages include a velum and 1 – 2 pairs of small papillae behind this. Tube feet 5 – 10 pairs. Calcareous ring pieces with seven pairs of arms. Dorsal ossicles are crosses with well-developed apophyses. Number of apophyses varying: one central apophysis arising from centrum of the cross, and one apophysis on each of the arms can be present. Ventral ossicles also cross-shaped with varying number of apophyses. Remarks. A rarely seen deep-sea genus known from mostly circumtropical and moderate latitudes. There are currently four accepted species of Psychroplanes worldwide, which had all been previously assigned to Peniagone (Hansen, 1975; WoRMS, 2024). This genus was erected to account for ossicles unique within Elpidiidae, robust crosses with arms arising from a single central point rather than a central beam (Gebruk, 1988). While the genus is not currently reported from Australia in ALA, Psychroplanes rigida (as Peniagone rigida) was collected from the eastern Australian abyss off New South Wales in 2017 (NMV Catalogue, 2024). Four lots of Psychroplanes convexa are recorded here from the IOT voyages at depths of 2973 – 4990 m. Diagnosis from translation of the original Russian (Antonina Kremenetskaia, pers comm., 2024).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A53527BFFB9FF29E9CBFCA4FD30.taxon	materials_examined	Material examined. NMV F 308185 (1) [IN 2022 V 08 115]; NMV F 308230 (1) [IN 2022 V 08 122]; NMV F 308284 * (1) and NMV F 308285 (1) [IN 2022 V 08 151]. Diagnosis of IOT material. Preserved specimens soft, ovoid, opaque to cream or light purple to grey. Dorsally high and curved, ventrally flattened with sole. All specimens damaged but similar “ pig shape ” to Amperima. Length: width ratio ~ 2: 1, up to 10 cm long and 5 cm wide (NMV F 308284, preserved). Anterior velum damaged but broad and thick. Mouth ventral, up to ten tentacles with soft often folded discs, lobed at edges, on short / thick stalks. Large discrete tube feet bordering ventral sole (> 5 each side). Skin a little rough / prickly due to cross-shaped ossicles. Cross-ossicles of variable size and predominantly two types. Slender type with four horizontal base arms originating from the centre, and four shorter horizontally directed apophyses, giving the appearance of a small cross on top of a large one when viewed from above (fig. 10 e). Arms are smooth with typically bluntly spinous ends (fig. 10 f). More robust cross-ossicles, less regular than the slender type, with four outwardly projecting arms, slightly curved up at end and variably spinous (fig. 10 g – j). Arms and four shorter vertical, straight to outward-curving apophyses originate from a square-like centre. Tentacles and tube feet similar, with some rods also seen. Remarks. Presence of true cross ossicles with arms arising directly from centre place these specimens in Psychroplanes rather than Peniagone. Morphologically also like Psychroplanes obsoleta (Hérouard, 1899), which has not been recorded for the Indian Ocean, but more than five pairs of tube feet places this in Psychroplanes convexa (Hansen, 1975). Minute dorsal pair of papillae behind anterior velum not seen in these damaged specimens. All specimens have ossicles matching the original P. convexa description and illustrations (Hansen, 1975), though NMVF 308284 (fig. 10 e – g) and NMVF 308285 (fig. 10 h – j) are the most typical, with some Peniagone - style ossicles seen in tentacles for NMVF 308230 and some more irregular and spinous versions of robust crosses in NMVF 308185. There is insufficient resolution in the COI data to confidently determine its phylogenetic placement within Elpidiidae (fig. S 1). Distribution. Indian Ocean: off east Africa to Sri Lanka, Australian IOT. Full bathymetric range. 2973 – 4990 m (IOT 2973 – 4990 m). Type locality. Indian Ocean, between Madagascar and Mombasa, and off Sri Lanka, 4040 – 4820 m. This species and genus not previously recorded from Australia in AFD or ALA (accessed January 2024). This IOT material represents a geographic and bathymetric range extension for the species and the first record for Australia. References. AFD (2024), ALA (2024), Gebruk (1988), Hansen (1975)	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A53527BFFB9FC8BE9EBFBFDFB57.taxon	diagnosis	Diagnosis (following Hansen, 1975). Dorsal papillae separated into one pair of large anterior papillae, and one large and one small pair placed close together on the middle or posterior part of the body. Tentacle discs with a few, large papillae on the surface and a knobbed margin divided into a pair of large, aboral, retractile lobes. Ossicles consisting of rods and Cs. Calcareous ring consisting of five isolated pieces, each with four pairs of arms. Remarks. Scotoplanes are a charismatic genera of sea cucumber and one of the groups often referred to as sea pigs. They have been observed to aggregate in large densities, particularly around food sources such as whale fall (Gutt and Piepenburg, 1991) and have also been known to host parasitic or hitchhiking invertebrates (Barry et al., 2017). Of the five currently accepted species of Scotoplanes worldwide, only S. globosa has been previously recorded for Australia (WoRMS and ALA January 2024). A single lot of S. globosa was recorded from the IOT voyages at 1019 – 1023 m.	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A53527BFFA7FC8BEE4AFB9DF982.taxon	description	Figure 11 a – f, Appendix 1, Table S 1	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A53527BFFA7FC8BEE4AFB9DF982.taxon	materials_examined	Material examined. NMV F 308303 (4) [IN 2022 V 08 157]. Diagnosis of IOT material. Specimens small and damaged with minimal features; soft, round to oval “ pigs ” up to 40 mm long and 24 mm wide (preserved). Light pink with smooth, thin, and partially transparent skin. Mouth terminal to ventral with ring of mostly removed orange / red tentacles. Specimens grey when preserved. Anus subdorsal to terminal. Discrete tube feet along outer sides of ventrally flattened sole and some evidence of dorsal papillae. Ossicles only S. globosa type rods (104 – 376 μm) and small Cs (32 – 56 μm). Rods variably spinous, particularly distally, and Cs variably individual or clumped (fig. 11 e). Remarks. These specimens are small compared to one type specimen recorded at 18 cm long (Théel, 1879), and the single ~ 5 cm specimen collected previously from Australian waters (O’Loughlin et al., 2020), however specimens have been recorded from off Cape Point, South Africa, at a maximum size of 15 mm (Thandar, 1999). Distribution. Largely cosmopolitan (excluding North Atlantic) and typically at depths of over 1000 m. Full bathymetric range. 545 – 6770 m (Hansen, 1975 in reference to Ohshima, 1915 and Thandar, 1999) (IOT 1019 – 1023 m). Type locality (as Elpidia globosa). Southern Indian Ocean south of Australia, 3566 m, and South Pacific Ocean off Chile, 3950 m. This species not previously recorded from Australia in AFD but recorded from a single station in Freycinet Marine Park off north-east Tasmania at 2751 – 2820 m in ALA (January 2024). This IOT material represents a geographic range extension for the species in Australia. References. AFD (2024), ALA (2024), Gebruk (1983), Hansen (1956), Hansen (1975), O’Loughlin, Mackenzie and O’Hara in O’Hara et al. (2020), Thandar (1999), Théel (1879), Théel (1882), Takano et al. (2019).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535265FFA4FC8BED15FE73FC8C.taxon	materials_examined	Material examined. NMV F 296840 * (1) [IN 2021 V 04 007]. Diagnosis of IOT material. A single additional specimen lot identified to Elpidiidae. Specimen was severely damaged (in two pieces), opaque pink / orange gelatinous specimen. No real shape retained but with approximately seven darker red tentacles remaining. One specimen piece> 50 mm long and ~ 25 mm wide from shipboard photograph. Irregular branched ossicles, not crosses, large and flat, ~ 650 μm in diameter, with a short smooth central beam branching into up to eight long (up to ~ 460 μm) spinous arms, but no apophyses or other vertical structures. Rare additional smoother irregular branched crosses up to 136 μm long, plus Peniagone - style crosses with short apophyses and out-turned arms. Remarks. No likely species were found in Hansen’s (1975) Elpidiidae key and descriptions, and no similar ossicles are observable in more recent publications. Based on COI and 16 S, this specimen is basal to Peniagone. For 16 S, it forms a clade with Protelpidia murrayi, Amperima robusta, and Scotoplanes hanseni, but there is no support for this grouping in COI (fig. S 1). Without additional material, this specimen is kept at family level for now. Distribution. This specimen lot only: Indian Ocean, Australian IOT, Christmas Island Territory, Christmas Island SE Stn., 3200 – 3345 m. References. Danielssen and Koren (1879), Hansen, (1975), Kremenetskaia et al. (2021).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535266FFA4FF31EE81FCD6F885.taxon	diagnosis	Diagnosis (following Hansen, 1975). Circumoral papillae present. Midventral tube feet absent. Dorsal papillae small, in single rows, double rows, or bands. Ventrolateral papillae absent. Ossicle wheels lack marginal teeth. Remarks. Of the three currently accepted species of Benthogone worldwide, two have been previously recorded for Australia: B. abstusa and B. fragilis, both off northwestern Australia (WoRMS and ALA January 2024 *). Five lots of Benthogone were recorded from the IOT voyages at depths of 2156 – 2435 m, with four of those identified as B. rosea – a new species record for Australia.	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535266FFA4FF36E806FCD1FA0E.taxon	diagnosis	Diagnosis (amended from Rogacheva et al., 2009). Ossicles wheel-shaped, scattered rods or (in Laetmogone violacea) spinous crosses or (in Gebrukothuria) rods only. Tube feet conspicuous, evenly distributed along entire ventrolateral radii, never fused into a brim. Midventral tube feet present or absent. Papillae numerous, placed along dorsal radii or dorsal and ventrolateral radii; papillae on dorsal radii free, on ventrolateral radii (if present) free or fused; in rare cases fused to form an anterior brim. Circumoral papillae present or absent. Calcareous ring reduced or not calcified. Gonad composed of numerous branched ducts and tubules. Remarks. The Laetmogonidae are a cosmopolitan family with seven currently accepted genera, three of which were previously recorded for Australia: Benthogone, Laetmogone and Pannychia. Found most commonly on the continental slope, these sea cucumbers have an elongated body with dorsal papillae and ventral-oriented feeding tentacles. IOT material includes examples from Benthogone and Psychronaetes. Diagnosis of family amended here to include rare case of fused anterior brim.	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535266FFA2FC90EBB6FCD6FB97.taxon	description	Hérouard, 1923: 38 – 39. — Heding, 1940: 369. — Madsen, 1947: 15 – 16. — Pawson, 1965: 219 – 221, pl. 5. — Gebruk et al. 2014: 159. Benthogone rosea var. cylindrica Perrier, 1896: 900. Benthogone rosea var. 4 - lineata Perrier, 1896: 900. Benthogone quadrilineata. — Heding, 1940: 369. — Heding, 1942: 15. Non Benthogone quatrolineata. — Augustin, 1908. Material examined. NMV F 296864 * (12) [IN 2021 V 04 031]; NMV F 308147 (1) and NMV F 310371 (1) [IN 2022 V 08 105]; NMV F 308320 (1) [IN 2022 V 08 187]. Diagnosis of IOT material. Specimens typically gelatinous, light red, pink, or mauve colour before preservation, with ventral colour often darker, particularly along the midventral, which was occasionally furrowed. Firmer and purple to mauve when preserved. Elongate body slightly raised and curved dorsally, rounded anteriorly and posteriorly and with thin lateral edges. Anus terminal, subdorsal. Ventral mouth often with a darker colouration than body, 15 – 20 retractable peltate purple tentacles surrounded by circumoral ring of small papillae (fig. 12 c). Dorsal radial rows of slender papillae (often retracted and / or hard to detect), and ventral retractable tube feet on lateral margins, with end-disks often visible. IOT specimens up to 110 mm long, 17 mm wide and 7 mm high (NMV F 308320 preserved), but average specimen less flattened (e. g. 65 mm long, 12 mm wide and 12 mm high; NMV F 296864.1 – preserved). Body wall ossicles large to small Laetmogone - like wheels, slightly curved, with central four-rayed raised primary cross. Wheelssymmetrical but perimeter is undulating and size graduates from small to large. Larger wheels more typically with eight spokes ~ 104 – 218 μm dorsally but smaller ventrally. Smaller wheels nine (typically 10 or more) spokes and ~ 70 – 118 μm. No teeth on rims. The wheel centre is almost filled, with only a narrow slit or hole in the calcareous membrane (presumably the nave as noted in Hansen, 1975), typically below the primary cross. Tentacles with clumps of irregular, curved spinous rods plus wheels. Wheels also observed in papillae and tube feet. Remarks. There are many similarities with Laetmogone, but for intact specimens the presence of circumoral papillae distinguishes Benthogone from other genera in Laetmogonidae. The IOT material was a good match to the type description for B. rosea, though the midventral was more rust-red than “ striking purple ” and some of the wheel sizes differed as noted below. Distinguished from B. fragilis, which has greater number and different distribution of papillae, and from B. abstrusa, which has unretractile larger tube feet and conical dorsal papillae. Spinous rods were only observed in tentacles, some of the larger wheel ossicles were up to 218 μm – much larger than the type specimens for the species in Koehler (1895) (100 μm) and those observed in Hansen (1975) (160 μm). Hansen also saw no correlation in wheel size and spoke number, whilst we observed (like Koehler in the type specimens) typically eight spokes in the larger wheels for IOT specimens, and typically ten or more spokes for smaller wheels. Some specimens had lost some or all their 15 – 20 tentacles though trawl damage. Note that the outer skin was susceptible to damage or stripping during collection, and specimens clumped together during preservation, making it harder to see external characters later. Good shipboard photography in and out of water pre-preservation assisted with the observation of external characters. In addition to the original description (and illustration) in Koehler (1895), Hansen (1975) provides some good descriptions and keys and can be used in conjunction with the Laetmogone character table from Thander (1998) to rule out Laetmogone and other Benthogone species. The specimen sequenced for COI and 16 S (NMV F 296864) does not group with Benthogone abstrusa in either gene tree; genetic placement within Elasipodida is unclear (fig. S 1). Based on morphological features, we maintain its identification here as B. rosea. Distribution. Eastern North Atlantic from Ireland to Cape Verde (off Mauritania), north of New Zealand (South Pacific), and Indian Ocean (off east Africa and Australian IOT) (Hansen, 1975; Gebruk et al., 2014; this work). Full bathymetric range. 1103 – 2480 m (Hansen, 1975; Gebruk et al., 2014) (IOT 2189 – 2435 m). Type locality. North Atlantic, Bay of Biscay, 1300 m. This species not previously recorded from Australia in AFD or ALA (January 2024). This IOT material represents a geographic range extension for the Indian Ocean and first record for Australia. References. AFD (2024), ALA (2024), Gebruk et al. (2014), Hansen (1975), Koehler (1895), Massin (1993), Thandar (1998).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535262FFA0FF36EE47FD69F98C.taxon	diagnosis	Diagnosis. (see Ludwig, 1893) Remarks. Widespread at bathyal to hadal depths, the Pelagothuriidae are a small family of swimming sea cucumbers with only two currently accepted genera and species: Enypniastes eximia and Pelagothuria natatrix. Both employ a brim of fused tube feet for swimming, though only P. natatrix is thought to be truly pelagic. Only Enypniastes has been reported for Australia, and again only this genus was found in the IOT material.	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535262FFAEFC93EF1BFEB0F913.taxon	materials_examined	Material examined. NMV F 296837 * (1) [IN 2021 V 04 005]; NMV F 296847 * (1) [IN 2021 V 04 013]; NMV F 308201 (1) [IN 2022 V 08 116]; NMV F 308208 (1) and NMV F 308209 (1) [IN 2022 V 08 117]; NMV F 308331 (1) [IN 2022 V 08 195]. Diagnosis of IOT material. Specimens fragile, gelatinous, and bulbous with a convex dorsal surface, flattened ventrally, wider anteriorly, and often translucent, with visible gut. IOT specimens reddish-brown to dark purple with a whiteish, translucent cover and up to 100 mm long and 35 mm wide (NMV F 308201 pre-preservation). Mostly light grey with some purple after preservation. Anus dorsal. Mouth ventral behind distinctive broad anterior cowl, up to 65 mm wide, made from a brim of fused tube feet, presenting as canal-like projections with processes at ends, often damaged, torn, and stringy in preserved specimens. Tentacles and canals in anterior cowl typically a darker maroon purple. IOT specimens are all damaged with few additional features, but when visible these include large leaf-like bifurcated tentacles, irregular dorsal papillae (fig. 14 b), and two fin-like posterior lateral brims made from fused tube feet (fig. 14 c). Ossicles, internal respiratory trees, and calcareous ring are all absent in this species. Remarks. The previous six species of Enypniastes were all synonymised (Gebruk, 1989) making E. eximia the only likely identification here. Descriptions of the type specimens (Théel, 1882) and more complete collected specimens (e. g. Sluiter, 1901 a; Wirawati and Setyastuti, 2021) include a typical body ratio of 1: 2 (twice as long as wide), 12 – 14 canals in the anterior cowl, up to 20 leaf-like bifurcated tentacles, long dorsal papillae of varying number, and 8 – 15 fused podia creating the two fin-like posterior lateral brims. Some additional free lateral tube feet are noted in Sluiter, but Wirawati and Setyastuti note that tube feet are absent. Type specimens are 72 mm long and 32 mm wide, but species has been observed up to 250 mm in length (Rowe et al., 2017). Despite damage, available morphology in IOT specimens matches previous reports, including ~ 1: 2 body ratio, though occasionally more elongate. Based on 16 S sequences, p-distances between samples here range from 2.3 % to 6.6 % (fig. S 1). For Holothurians, this falls within the range of within-species divergence, so we are comfortable with identifying all specimens here as E. eximia. Distribution. Cosmopolitan with global distribution including reports from as far north as the Aleutian Trench off Alaska, south to Antarctica, and from surface to hadal depths (6900 m Java Trench). Very common in north-east Atlantic. Full bathymetric range. 0 – 6900 m (IOT 643 – 1991 m). Type locality. South Pacific Ocean (off north-east New Zealand), 2030 m. This species reported as widespread in Australia in AFD (January 2024) and recorded from surface to 2259 m in ALA (January 2024) including off Western Australia, New South Wales, Tasmania, and South Australia (Great Australian Bight). This IOT material agrees with worldwide distribution of the species. References. AFD (2024), ALA (2024), Billett et al. (1985), Gebruk (1989), Gebruk et al., (2014), Miller and Pawson (1990), Rogacheva et al. (2013), Rowe, O’Hara and Bardsley in Byrne and O’Hara (2017), Sigwart et al. (2023), Théel (1882), Wirawati and Setyastuti (2021).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A53526CFFAEFF36ED85FBE7FE6A.taxon	diagnosis	Diagnosis (following Hansen, 1975). Tentacles 10 – 18. Brim of tube feet surrounding the body and midventral tube feet present. Ossicles cross-shaped or rod-shaped. Calcareous ring absent or consisting of a diffuse network. Remarks. Psychropotidae are a widespread deep-sea family, typically found from abyssal depths to the continental slope. The group includes the often photographed “ Gummy Squirrel ” Psychropotes with its sail-like dorsal appendage (Heffernan, 2019). Of the three currently accepted genera, two – Benthodytes and Psychropotes – are found in Australian waters. At least three species of Benthodytes and three of Psychropotes were observed for the IOT here.	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A53526CFFACFC93EE2DFBF5FDB1.taxon	materials_examined	Material examined. NMV F 308170 * (1), NMV F 308171 * (1) and NMV F 308177 (1) [IN 2022 V 08 113]; NMV F 308197 * (2) [IN 2022 V 08 116]; NMV F 308269 (3) [IN 2022 V 08 145]; NMV F 308327 (1) [IN 2022 V 08 191]. Diagnosis of IOT material. Large light violet specimens with dark-purple tentacles and tube feet, and some darker purple to maroon-red remnant patches. Elongated, semicylindrical body, highly convex dorsally, clear flattened sole ventrally, rounded anteriorly and rounded to slightly tapered posteriorly. Body solid. Skin thin and firm, thicker ventrally, occasionally more gelatinous, particularly dorsally, and appearing to bubble or form warts in places. Anus dorsal, close to terminal. Mouth ventral with circumoral papillae. Up to 15 peltate tentacles (sometimes 10 or 11). Single rows of up to eight (4 pairs) of well-spaced papillae along dorsal radii, variable size and tapered at ends. Typically, very narrow lateral brim of short, fused tube feet. Midventral tube feet small, in irregular double row, sometimes bare just below the mouth. IOT specimens large (e. g. 230 mm long, 50 mm wide and 35 mm high: NMV F 308327 – preserved). Dorsal body wall ossicles large and small crosses, variably thick and thin, typically with distally spinous arms and central apophyses (broken). Arm length variable (e. g. 176 – 336 μm: NMV F 308170), sometimes with corkscrew-like spinous ends. Papillae often same. Smaller crosses typically finer and less spinous, some with no apophyses. Ventral ossicles thick spinous crosses with irregular spinous central apophyses, reduced crosses with and without apophyses, and smooth straight rods with spinous ends. Tentacles straight to curved rods with spinous ends. Remarks. These specimens vary widely. Specimens match descriptions and illustrations of external morphology for Benthodytes incerta using Hansen (1975), but bipartite apophyses were not seen on crosses (though apophyses were typically broken). Ossicles can key to B. superba, but other features do not match. One specimen (NMV F 308327) has tube feet more “ free ” than typical when observed in water, and one deeper specimen lot (NMV F 308269 from ~ 3000 m) has a more prominent brim and more “ warty ” skin than others, but both still fit the general morphology for B. incerta. NMV F 308177 is partial (skin only), but skin and ossicles match others in group. Specimens differ from B. marianensis in ossicles and body form, including narrower brim and fewer dorsal papillae. Specimens have a very similar body form to B. manusensis, but with more dorsal papillae, typically a narrower brim, and different ossicles from those shown in Xiao et al. (2018). Most specimens are distinguished also from B. lingua, which is thicker and more gelatinous with no clear ventral sole. One specimen (NMV F 308171) has a B. lingua morphology agreeing with illustrations in Perrier (1902: pl. 12: 1 – 2), and images of exposed ovaries in Hansen (1975: pl. 12: 2). As discussed under Remarks for the genus, genetics clearly places the specimen with this IOT B. incerta group. Without additional specimens including type material for comparison, we do not attempt to assess the validity of B. lingua as a species. We acknowledge the variation in specimens here and that material potentially represents a new species but identify all to Benthodytes cf. incerta for now. Distribution. These specimen lots only: Indian Ocean, Australian IOT, Christmas Island and Cocos (Keeling) Islands Territories, Lucia Seamount Stn., Scrooge Seamount Stn., Cocos (Keeling) Stn., and Santa Ridge Stn., 1304 – 3078 m. Full bathymetric range. 1304 – 3078 m. References. Hansen (1975), Li et al. (2018), Ludwig (1893, 1894), Xiao et al. (2018).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A53526EFFADFC93E96BFDD4FEE7.taxon	materials_examined	Material examined. NMV F 308225 * (1) [IN 2022 V 08 122]. Diagnosis. Specimen elongated, slightly raised mid-dorsally but flattened anteriorly, and flattened and tapered posteriorly, 24 cm long, 4.5 cm wide and 1.5 cm high (preserved). Pink to brown and purple (pre-preservation). Heavily damaged and outer skin appears to be stripped, leaving the specimen fluffy. Dorsal radial bands visible, but papillae minute or lost. Midventral line also visible, but tube feet lost. Fused lateral brim of tube feet. Anus dorsal, close to terminal. Mouth ventral, with clear anterior brim of post-oral papillae. At least 16 soft tentacles with marginal processes visible in this specimen, retracted into skin folds. Ossicles rare, only a few irregular smooth rods up to 256 μm long. Remarks. Superficially different from images of Benthodytes cf. sanguinolenta reported from the CCZ (Bribiesca et al., 2022) and morphologically congruent (where features available) with the diagnosis and whole-body photographs (pl. 3 – 6) of B. sanguinolenta from Hansen (1975). Not identified past Benthodytes cf sanguinolenta here due to the poor state of the specimen. Distribution. This specimen lot only: Indian Ocean, Australian IOT, Cocos (Keeling) Islands Territory, Investigator Ridge Abyssal Stn., 4980 – 4990 m. Full bathymetric range. 4980 – 4990 m. References. Bribiesca et al. (2022), Hansen (1975), Li et al. (2018), Ludwig (1894), Théel (1882).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535269FF96FC8BED0FFB71FCFF.taxon	materials_examined	Material examined. NMV F 296865 * (2) [IN 2021 V 04 033]; NMV F 296881 * (1), [IN 2021 V 04 050]; NMV F 308148 * (1) [IN 2022 V 08 105]; NMV F 308194 (2) and NMV F 308195 (2) [IN 2022 V 08 115]. Diagnosis of IOT material. Medium to large violet specimens up to ~ 255 mm long, 45 – 75 mm wide and 50 mm high (NMV F 308195, preserved, widest at anterior brim). Unpaired, flaccid dorsal appendage, tapering from a wider base to narrow rounded tip, variable in size, approximately one quarter to one seventh of the length of the body in preserved specimens. Dorsal appendage placed at variable distance from the posterior end of the body, but typically one third of a body length from the end. Skin soft and smooth to wrinkled, thin dorsally, usually thicker ventrally. Light purple and pink dorsally, often with darker patches or sometimes semitransparent showing gut contents. Darker purple to rust-red around brim, tentacles, tube feet, and often ventrally. Body form elongate, dorsally raised, ventrally flattened, surrounded by a narrow to very broad brim of enclosed tube feet, sometimes with free filamentous tips, brim often wider anteriorly. Anus ventral, terminal (under brim). Mouth ventral. 18 retractile tentacles, rounded with marginal knobs on discs. Midventral tube feet present throughout nearly entire length of sole, semi-retracted, small to medium and conical, in paired to zigzag row. Up to four pairs of reduced (e. g. <5 mm) dorsal papillae (NMV F 308194, NMV F 308195), but otherwise inconspicuous or retracted to bumps. Dorsal body wall ossicles are cross-shaped with four arms and one smooth central spine-like apophysis. Arms with gentle to strong curve, length variable (e. g. 136 – 429 μm), distally spinous but with one or more additional vertical spines and occasionally some extra serrations projecting from the dorsal surface before the arm curves. Rarely a lot more spinous, with spines projecting from both dorsal and ventral surfaces (fig. 19 g). Papillae ossicles similar. Ventral ossicles rods (e. g. 320 – 440 μm) and rare reduced crosses. Tentacles with straight to curved rod ossicles (e. g. 400 – 528 μm), spinous at ends and occasionally branching. Remarks. Specimens resembled the original (Théel, 1882) and Galathea Report (Hansen, 1975) descriptions for Psychropotes depressa, and keyed closest to that species based on external morphology and ossicles, however placement and measurements for the dorsal appendage were more variable in IOT specimens. Two specimens, NMV F 296881 and NMV F 308148 (fig. 20 k – m) were both bulbous and full of mud, with stretched, thin skin, and very tapered and narrow at the anterior once preserved. NMV F 296881 was quite damaged and missing its dorsal appendage once preserved. Genetics (fig. S 1) confirm these specimens fit with other IOT P. depressa, and both morphologies are shown in the accompanying figures. Distribution. Cosmopolitan. * Full bathymetric range. 957 – 4200 m * (IOT 2289 – 3100 m). Type locality. North Atlantic Ocean (south of Portugal), 1993 – 2515 m. * Reported from Atlantic and Pacific to 4200 m by Rogacheva et al. (2013), but as cosmopolitan to 4060 m by Gebruk et al. (2014). Hansen (1975) is a mix of both. This species previously recorded for Australia in AFD (Lord How Rise) and from the eastern coast of Australia off Bermagui in NSW to the Coral Sea in Queensland at depths of 1761 – 2902 m in ALA (January 2024). This IOT material represents a geographic and bathymetric range extension for the species in Australia and new record for the Indian Ocean (no records for this region on the Ocean Biogeographic Information System [OBIS], January 2024). References. Gebruk et al. (2014), Hansen (1975), OBIS (2024), Rogacheva et al. (2013), Théel (1882).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535254FF94FC93E8D1FF07F939.taxon	description	Non: Psychropotes longicauda var. monstrosa Théel, 1882: 98 – 99, pls. 29: 2, 30, 39: 1. Non: Psychropotes longicauda var. antarctica Vaney, 1908: 419 – 420. Material examined. NMV F 308333 * (1) [IN 2022 V 08 196]. Diagnosis of IOT material. Single specimen, elongate and semicylindrical, with a rounded dorsal surface, slightly constricted before additional dorsoanterior bulging, flattened ventrally, and flattened at each end once preserved, ~ 125 mm long, 37 mm wide and 20 mm high (preserved). Soft but unusually firm for this typically gelatinous species and almost black shipboard (see Remarks). Dark purple to violet / red preserved. Unpaired dorsal appendage of same colour as body, fin-like in appearance, and very close to posterior end; firm rather than flaccid and gelatinous, almost the width of body but shorter than expected (approximately one fifth the size of specimen). Anus ventral. Mouth ventral. Eighteen tentacles with very round firm discs and knobbed margins. Anterior brim of more than ten tube feet, variable in size, fused for most of their length but free and round at ends. Similar for a much smaller posterior brim, with approximately ten tube feet, more regular in length. Ventrolateral tube feet large and free, approximately seven each side. Paired to zigzag series of large to small midventral tube feet. No dorsal papillae observed in this specimen, usually minute. Ossicles irregular spinous crosses and rods. Dorsal body wall ossicles (fig. 21 e, f) slender and spinous to thick and serrated crosses, with and without central apophyses, most broken here. Ventral body wall ossicles (fig. 21 g – k) typically stout, slightly curved crosses, with or without broken central apophyses, arms up to ~ 91 μm long with scattered spines mostly distal (fig. 21 g – i). Also, slender crosses with longer arms up to 350 μm with or without central apophysis (fig. 20 j, k), and rare rods. Tentacles with curved to straight, smooth to spinous or branched rods up to 640 μm long. Remarks. We have placed our specimen in P. longicauda for now with the usual reservations, and in particular noting that Gubili et al. (2017) assessed P. longicauda as a cryptic species complex and Gebruk et al. (2020) redescribed and split the species. The 16 S sequence groups with that of P. longicauda from California, USA (fig. S 1). Our specimen was collected from a station with manganese nodules, so the black colour and firmer texture here may be artifacts rather than typical. Ossicles and external morphology key closest to P. longicauda in the Galathea Report (Hansen, 1975), with ossicles and features a good match other than the IOT specimen having a slightly reduced dorsal appendage. Ossicles and preserved whole-body dimensions from the original description in the Challenger Reports (Théel, 1882) agree with the IOT specimen, but again the dorsal appendage for our specimen is much shorter and more tapered than the “ very large ” 120 mm one noted in the original description, and those illustrated by Gebruk et al. (2020) or photographed by Ross (2012). The IOT specimen also shows some similarities to the variety now accepted as P. fuscopurpurea Théel, 1882 known only from the type locality in the Southern Indian Ocean south of Australia at ~ 3560 m. The differences between these species were covered well in the redescriptions by Gebruk et al. (2020), with our specimen judged a closer match to the ossicles from P. longicauda. Distribution. Australian IOT (this work), Indian Ocean sector of the Antarctic, Pacific Ocean: Kermadec Trench area. * Full bathymetric range. 3431 – 5414 m * (IOT 3431 – 5414 m). Type locality (for specimen noted as “ best ” for species). Southern Indian Ocean, Southern Ocean (northwest of Casey Station Antarctica), ~ 3614 m. * Prior to Gebruk et al. (2020), which restricted geographic distribution to the Indian Ocean sector of the Antarctic and the Kermadec Trench area (depth 3560 – 5414 m), distribution was considered cosmopolitan at 2210 – 5173 m. This species was previously recorded in AFD and from western, eastern and southern Australia at depths of 815 – 4890 m in ALA (January 2024). Note that the NMV Catalogue records one of these specimens (from the Great Australian Bight) at a depth of 4890 – 5032 m. This IOT material represents a geographic and small bathymetric range extension for the species. References. AFD (2024), ALA (2024), Gebruk et al. (2014), Gebruk et al. (2020), Gubili et al. (2017), Ross (2012), Théel (1882).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535250FF92FF36ED3FFB75FCDA.taxon	diagnosis	Diagnosis. (following Gebruk et al., 2012). Body nearly cylindrical, slightly tapered toward both ends, without marginal fringe. Ventral side somewhat flattened; dorsal side uniformly covered with small pedicles of small and equal size, or much smaller dorsally, where they can be hardly visible. Tube feet with sucking disks scattered over entire body. Usually 20 tentacles, very occasionally 18 – 22. No tentacle ampullae; stone canal attached to body wall without penetrating it. Mouth terminal, anus ventral or subventral. Calcareous ring with rectangular radial segments. Gonads only on left side of dorsal mesentery, in single tuft. Ossicles of body wall quadri-radiate or tri-radiate tables with central primary cross elevated from disk. Remarks. Cosmopolitan genus with 26 species worldwide, 11 of which have been reported previously for Australia: Mesothuria abbreviata, M. bifurcata, M. carnosa, M. lactea, M. marginata, M. murrayi, M. norfolkensis, M. parva, M. regularia, M. sufflava and M. verrrilli (WoRMS and ALA January 2024). Two new species for Australia are recorded here: M. cathedralis, and M. gargantua. Twenty-four lots of Mesothuria were recorded from the IOT voyages at depths of 754 – 3345 m, with all further identified to OTU species level as follows: M. cathedralis (2 lots), M. gargantua (19 lots), and M. murrayi (3 lots). Distinguished from Zygothuria by semicylindrical body shape, full covering of papillae and typically quadri-radiate compared to tri-radiate table ossicles. In both the COI and 16 S datasets (fig. S 2), Mesothuria is paraphyletic with M. cathedralis, M. gargantua, and M. oktaknemus forming a well-supported monophyly and M. murrayi in a separate clade. For COI, M. murrayi and Holothuria hilla form a single, well-supported lineage but the 16 S phylogeny supports M. murrayi as monophyletic.	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535250FF92FF36E82BFDDAF9E4.taxon	diagnosis	Diagnosis. (following Smirnov, 2012 and amended for Miller et al., 2017 erection of Holothuriida). Body elongated, rounded, or flattened. Tube feet present along entire ventral side (genus Mesothuria) or only along ventral ambulacra (genus Zygothuria). Papillae virtually evenly spread on dorsal surface. Twenty (13 – 22) tentacles with no free-hanging tentacle ampullae present. Stone canal attached to the body wall without penetrating it. Rete mirabile not developed. Radial muscle bands undivided. Gonads in a single tuft of tubules to the left of the mediodorsal mesentery. Calcareous ring well developed. Table ossicles with large, laced disc perforated with large holes, and spire composed of three or four pillars surrounding the central hole. Remarks. This family exhibits primarily table-shaped ossicles and gonads in a single tuft. The only two accepted genera worldwide, Mesothuria and Zygothuria, are distinguished in external morphology by tube foot arrangement, body form, structure of calcareous ring and ossicles (Gebruk et al., 2012). Both genera have been reported widely from Australia at depths of 373 – 4250 m (AFD and ALA, 2024), and are again represented here in IOT material. Miller et al. (2017) maintained the Smirnov (2012) erection of Mesothuriidae, moving it from its former position in Aspidochirotida to their new order Holothuriida. See Smirnov (2012) for further comments on distinguishing traits between families.	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535250FF90FC93E8CCFD10FB5E.taxon	materials_examined	Material examined. NMV F 308202 * (4) [IN 2022 V 08 116]; NMV F 308237 (1) [IN 2022 V 08 126]. Diagnosis of IOT material. Small Mesothuria species, elongated cylindrical to oval shape, slightly flattened ventrally, with soft, wrinkled, cream-grey to light brown skin, sometimes with a pink tinge. Mouth subventral. Tentacles retracted in IOT specimens and not dissected, but ~ 20 expected. Anus terminal. Scattered cover of papillae and tube feet all over the body, often longer and more visible as dense lateral or posterior-ventral patches. Elongated (but damaged and distorted) specimen from NMV F 308202 is ~ 110 mm long, 15 mm wide and 15 mm high, while others are closer to an oval or spindle shape once preserved (e. g. 34 mm long, 12 mm wide and 12 mm high: NMV F 308237, preserved). Body wall contains many quadri-radiate table ossicles made of a perforated base disc with elevated central primary cross and four tall vertical spires, joined in two places, and angled out to four (rarely three) spinous arms at the tips. Table dimensions up to ~ 120 μm across by 104 μm high (NMV F 308237). Base discs typically irregular with a central ring of approximately eight large irregularly rectangular perforations, often with a secondary outer ring of eight or more smaller round to triangular perforations, though this is variable. Remarks. Within Mesothuria the dense covering of tube feet is reminiscent of Mesothuria murrayi, but these specimens are distinguished by taller, more elegant ossicle tables, with long slender spires (joined in two places) and spinous ends. Along with the original description in Heding (1940), morphological identifications were made using the additional images and keys from Gebruk et al. (2012) and notes and personal correspondence from O’Loughlin (2018). While these specimens represent a major geographic range extension for the species (see below), O’Loughlin (pers comm., 2018) also placed the species off eastern Australia at abyssal depths, with his specimens displaying table ossicles with 3 – 5 spires, but similar dimension to IOT specimens at 80 – 120 μm high, with a diameter of up to 128 μm across the table disc. The type specimen (Heding, 1940) had uniformly four spires, irregular or crooked at the apex, but our specimens were closer to those described by Gebruk et al. 2012, again with (typically) four spires, but more uniform at their spinous tips. Distribution. Atlantic Ocean, Indian Ocean (Australian IOT), and off eastern Australia from Tasmania to Queensland. * Full bathymetric range: 820 – 4930 m * (IOT 820 – 1991 m). Type locality. East Atlantic (Gulf of Guinea area), 2278 m. * Previous range from Gebruk et al. (2014) was limited to the Atlantic Ocean (various locations) with the depth from Rogacheva et al. (2013) at 1292 – 4930 m. While this species was not previously recorded from Australia in AFD or ALA (January 2024), the NMV catalogue has records from all eastern states, with specimens identified from off southern Tasmania to the Coral Sea in Queensland at depths of 1013 – 2650 m. These IOT specimens, along with other NMV catalogue records for Australia, represent a major geographic (and slight bathymetric) range extension for the species. References. AFD (2024), ALA (2024), Gebruk et al. (2012), Gebruk et al. (2014), Heding (1940), O’Loughlin (notes and personal correspondence, 2018), Rogacheva et al. (2013).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535252FF90FF36EE70FAEEF981.taxon	materials_examined	Material examined. NMV F 296863 * (1) [IN 2021 V 04 031]; NMV F 296873 * (2), [IN 2021 V 04 046]; NMV F 296880 (1), [IN 2021 V 04 048]; NMV F 308172 (1) and NMV F 308173 * (5) [IN 2022 V 08 113]; NMV F 308196 (1) [IN 2022 V 08 116]; NMV F 308215 (1), NMV F 308217 * (1) and NMV F 308218 (3) [IN 2022 V 08 117]; NMV F 308234 (1) and NMV F 308235 (1) [IN 2022 V 08 124]; NMV F 308236 * (1), [IN 2022 V 08 126]; NMV F 308252 (3), [IN 2022 V 08 136]; NMV F 308258 (2), [IN 2022 V 08 141]; NMV F 308260 (6) and NMV F 308265 (1), [IN 2022 V 08 143]; NMV F 308296 (2), [IN 2022 V 08 157]; NMV F 308305 * (1) [IN 2022 V 08 161]; NMV F 308328 (9), [IN 2022 V 08 191]. Diagnosis of IOT material. Conspicuous large white robust species, almost cylindrical but slightly flattened ventrally and tapering to rounded ends (e. g. 195 mm long, 55 mm wide and 55 mm high: NMV F 308260 largest specimen in lot, preserved). Skin thick and variably smooth to wrinkled. Mouth subventral to ventral with ~ 20 tentacles (typically retracted). Terminal anus. Midventral line or shallow furrow, sometimes rust-coloured or pink tinged here and between the wrinkles. Almost complete cover of small cylindrical tube feet, though these are inconspicuous at first glance on larger specimens; slightly larger and more obvious on the posterior part of the ventral surface but can be inconspicuous or absent from the anterior of the same. Skin densely packed with ossicles. Ossicles are large, solid, typically quadri-radiate tables made up of a perforated base disc with low spires made of four (rarely five) pillars, e. g. ~ 80 – 109 μm high, joined in one or two places with short spinous tips. Discs irregular and typically 150 – 190 μm in diameter, but can be larger (up to 280 μm, NMV F 308260). Many perforations, typically with inner ring of eight or more larger oval perforations, then more irregular, smaller ones towards the edge. Occasional anastomosing or branching on pillars, and edges of discs not always closed. Tube foot ossicles are similar but slightly smaller. Remarks. Identifications based on description in Deichmann (1930, 1954) with additional information from the clearer figures of type ossicles redrawn in SolÍs-MarÍn (2003) and subsequently Gebruk et al. (2012). Typically distinguished from other Mesothuria by being large, white and firm, with thick skin and robust, irregular ossicles. Two specimens, NMV F 308215 and NMV F 308305 (fig. 24 e), still grouped genetically with IOT M. gargantua but were smaller with softer wrinkled skin, and ossicles often with slimmer pillars with more elongated spines than other IOT M. gargantua. Distribution. Atlantic Ocean and Caribbean Sea, Indian Ocean (Australian IOT). Full bathymetric range. 720 – 1968 m (IOT 754 – 1968 m). Type locality. Caribbean Sea, off Barbados, 720 m. This species not previously recorded for Australia in AFD or ALA (January 2024). These IOT specimens extend the geographic and bathymetric range for the species (previously to 1347 m in Gebruk et al., 2012) and are the first records for Australia. References. AFD (2024), ALA (2024), Deichman (1930, 1954), Gebruk et al. (2012), Heding (1940), O’Loughlin (notes and personal correspondence, 2018), SolÍs-MarÍn (2003).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535252FF9FFC93ED1BFD36F8CD.taxon	materials_examined	Material examined. NMV F 296839 * (1) [IN 2021 V 04 007]; NMV F 296848 * (1) [IN 2021 V 04 016]; NMV F 308144 * (1) [IN 2022 V 08 105]. Diagnosis of IOT material. Light brown, elongated, cylindrical to semicylindrical specimens, typically medium to large, up to 18.5 cm long, 6 cm wide, 5.5 cm high (NMV F 296839 pre-preservation). Terminal to ventral mouth and terminal anus. Tentacles all retracted in IOT specimens (likely 20 but not dissected out). Complete cover of tube feet but very scattered and reduced mid-dorsal and mid-ventral, longer and more conspicuous in lateral bands along the sides of each specimen, with bands moving onto both dorsal and ventral surfaces. Ossicles variable tables, but typically tri-radiate made of a perforated base disc with elevated central primary cross and three pillars, joined by a single cross beam in the middle and again at the top. Topped by three spines / arms angled up or out and spinous at the tips (most broken off in our samples). Bases typically smaller (~ 110 μm) or larger (130 μm) discs, with central perforation and six or seven larger perforations. Smaller specimen (NMV F 296848) table base most typically ~ 100 μm with six large perforations plus some smaller perforations, and rarely (only one seen) ~ 90 μm table with many perforations and with four-pillared spinous spire lacking typical arms. Remarks. Specimens key to M. murrayi using Gebruk et al. (2012). Specimens agree with the type description (Théel, 1886 a) for M. murrayi general body form, tube foot distribution, and most ossicles. Ossicles with longer arms / spines not seen here (though most were broken) and remaining ossicles also look like M. maroccana, though this species itself may be just an age variation of M. murrayi (Gebruk et al., 2012). NMV F 308144 (fig. 25 d – f) has the body form closest to the type specimens, with body almost cylindrical, anus terminal, and mouth virtually terminal. All three have flexible skin though not obviously thin as recorded for types. NMV F 296848 (fig. 25 g) is a much smaller, flatter specimen. Distribution. Cosmopolitan. * Full bathymetric range. 246 – 6650 m * (IOT records 781 – 3345 m). Type locality. South-east Pacific Ocean (off Chile), 2502 m. * Many records may be unreliable (see remarks above and Gebruk et al. 2012). This species previously recorded from outside Cook’s Passage Queensland, west-central Pacific Ocean in AFD, and from Western Australia (off Perth), New South Wales, and east of Cape York Queensland in ALA (January 2024). This IOT material represents a geographic and bathymetric range extension for the species in Australia. References. AFD (2024), ALA (2024), Gebruk et al. (2012), SolÍs-MarÍn (2003), Théel (1886 a), Wirawati and Setyastuti (2021).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A53525DFF9FFC8BEBB6FAE3FB56.taxon	diagnosis	Diagnosis. (following Gebruk et al. 2012). “ Body ovoid, flattened, but with well-differentiated sole; integument often wrinkled. Tube feet arranged exclusively in single or double row along ventrolateral ambulacra, placed on sole margin, which often forms fringe. Tube feet widely spread, may be quite big; dorsal papillae minute, not numerous, irregularly distributed or arranged in two simple rows, sometimes totally absent. Twenty tentacles, rarely 13 – 19; no tentacle ampullae; madreporite placed close to body wall, without penetrating it. Mouth ventral or terminal, anus terminal, without special arrangement. Calcareous ring with triangular radial segments. Ossicles of integument three-pillar (rarely four-pillar) tables; close to middle of their length pillars are linked by transverse beams; pillars merge on top forming spire. ” Remarks. Deep-sea genus with six currently accepted species worldwide, two of which have been reported previously for Australia: Z. lactea from the south and east and Z. marginata from the northwest (WoRMS and ALA January 2024). Three lots of Zygothuria are recorded from the IOT voyages at depths of 1426 – 4766 m, and further identified to species OTU level as Z. lactea (1 lot), Z. thompsoni (1 lot, new species record for Australia), and Zygothuria sp. MoV. 7328 (1 lot). Distinguished from Mesothuria by flattened body shape with well-distinguished sole and fringe of ventrolateral tube feet, along with and typically tri-radiate compared to quadri-radiate table ossicles. With limited reviews of genera within Mesothuriidae available, we relied heavily on SolÍs-MarÍn (2003) and Gebruk et al. (2012) to identify specimens; both resources highlight the need for further study of the group. Based on both COI and 16 S sequence data, Zygothuria is monophyletic (fig. S 2). In the COI phylogeny, Z. thompsoni is sister to Z. oxysclera, but no 16 S data is available. Without additional samples matching the morphological and / or genetic description of specimen NMV F 296850, we are reluctant to identify this specimen past the current OTU level.	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A53525DFF9CFC8BEE49FB53FA0D.taxon	description	Figure 26 a – f, Appendix 1, Table S 1	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A53525DFF9CFC8BEE49FB53FA0D.taxon	materials_examined	Material examined. NMV F 308332 (1) [IN 2022 V 08 195]. Diagnosis of IOT material. Shipboard notes indicate this specimen was large, flat, very gelatinous, and stuck to the beam trawl net. Little structure and no real features remaining in preserved specimen, soft, wrinkled white tissue in broken pieces with some gut and stomach. Skin dense with tri-radiate Zygothuria ossicles. Base discs predominantly with six perforations (many also with eight). Three-pillared spires with three long, smooth, slender arms curving up from top, and one transverse beam between base and top. Rare similar tables with four pillars. Rare tables with a single off-centre spire. Remarks. Extensive damage to the specimen meant that identification was reliant on ossicles only. These keyed closest to Z. lactea using Gebruk et al. (2012) and were a good match to the ossicle illustrations and description in the same paper. Distribution. Cosmopolitan species, though records from the Gulf of Mexico and Caribbean may be unreliable (Gebruk et al., 2012). Full bathymetric range. 694 – 5278 m (IOT records 1426 – 1450 m). Type locality. Atlantic and Pacific Oceans, off the Azores and New Zealand, 1280 – 1830 m. This species not previously recorded for Australia in AFD but recorded at depths of 817 – 4250 m off the eastern coast of Australia (Queensland to Victoria) and in the Great Australian Bight off South Australia in ALA (January 2024, under previous taxonomy). This IOT material represents a geographic range extension for the species in Australia. References. AFD (2024), ALA (2024), Gebruk et al. (2012), Gebruk et al. (2014), Hansson et al. (2001), Östergren (1896), Théel (1886 a), SolÍs-MarÍn (2003).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A53525EFF9DFC93EE80FC2CF996.taxon	description	(incorrect spelling). Material examined. NMV F 308198 * (2), [IN 2022 V 08 116]. Diagnosis of IOT material. Elongate to oval specimens ~ 12 cm long x 4.2 cm wide, damaged, and atypically flattened or empty. Cream-coloured thin, wrinkled skin, but with some grey flecks and brown patches in places. Sole clearly defined by well-spaced series of tube feet on each ventrolateral margin, bare midventrally. No sign of dorsal papillae. Anus terminal. Mouth ventral to terminal. Small ossicle tables with predominantly three-armed pillars linked by two transverse beams and topped by three spires. Spires mostly broken but some indication that they are short compared with stem of pillar, and spinous. Bases typically ~ 240 – 290 μm, thick to thin, irregular with wavy edges and 12 or more elongate to oval or round perforations of varying size. No obvious placement of perforations based on size seen here. Rare thin, symmetrical hexagonal bases ~ 260 μm in diameter with six pentagon-shaped perforations (fig. 27 f). Remarks. Prominent tube feet on ventrolateral radii rather than tube feet scattered over entire body distinguish these specimens as Zygothuria not Mesothuria. Specimens key closest to Z. connectens or Z. thomsoni using Gebruk et al. (2012), but with ossicles a closer match to figures of Z. thomsoni (Théel, 1886) as redrawn in the same paper. Distribution. Pacific Ocean, Indian Ocean (Australian IOT), (and as Z. thomsoni var. hyalina from southern Indian Ocean with limited confidence). Full bathymetric range. 1991 – 5307 m (IOT 1957 – 1991 m). Type locality. North-west and mid-north Pacific, 3375 – 5307 m. This species not previously recorded from Australia in AFD or ALA (January 2024). This IOT material represents a geographic and bathymetric range extension for the species, previously only known from its type location, though with limited confidence. References. AFD (2024), ALA (2024), Gebruk et al. (2012), SolÍs-MarÍn (2003).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535258FF9BFC93EED9FE36FD68.taxon	diagnosis	Diagnosis. (following O’Loughlin et al., 2015, after Pawson, 1977). “ Calcareous deposits include tables, anchors, and rosettes of racquet-shaped plates and large fusiform rods in various combinations. Tail deposits tables or fusiform rods. Phosphatic deposits present or absent. ” Remarks. Samyn and VandenSpiegel (2016) commented that there has been no complete revision of Molpadia since Pawson put Trochostoma and eight other genera into the group between 1965 and 1977. Pawson himself noted the ongoing issues with successfully splitting the loosely defined group into multiple genera, and the acceptance between taxonomists to maintain it for practical purposes, until more is known (Pawson, 1977). There are 60 currently accepted species within Molpadia (WoRMS 2024), with eight of these previously known from Australia: M. adamanensis, M. antarctica, M. dissimilis, M. scabrum, M. abyssicola, M. granulata, M. musculus and M. lenticula (Rowe et al., 2017), though there are some discrepancies between this list and genera recorded in ALA and in the NMV catalogue. Additional work will be needed to resolve the distribution discrepancies for the genus within Australia. In the IOT we found two lots of Molpadia, both from stations over 3700 m, which we have identified here as Molpadia cf blakei. Tri-radiate tables with a three-pillared spire, along with the presence of phosphatic deposits and lack of plate / cup ossicles, puts specimens into Molpadiidae rather than Caudinidae, while lack of three-armed anchor plates puts them in Molpadia rather than Heteromolpadia (Pawson, 1977 key). Although we have a reduced dataset, both COI and 16 S sequence data indicates that Molpadia is paraphyletic, which is concordant with previous findings (Miller et al., 2017). Specific genetic placement of these IOT specimens is noted in Remarks for the species description below.	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535258FF9AFF36EE27FC6FFAC6.taxon	diagnosis	Diagnosis. (following O’Loughlin et al., 2015). “ Tentacles 15, digitate; body stout, lacking tube feet, usually with an evident tail; anal papillae, tentacle ampullae and respiratory trees present; ossicles may include tables, cups, rods, perforated plates and modified anchors; phosphatic bodies often present. ” Remarks. The Molpadida are burrowing holothuroids lacking any tube feet and with a sausage-like body often tapered to a tail. Despite the absence of tube feet, Molpadida do not group with the Apodida, though their position within the Neoholothuriida remains uncertain (Miller et al., 2017). Molpadida often bury themselves in mud or silt and are known from the subtidal zone down to abyssal depths (Pawson et al., 2001). They are represented worldwide by three families, with only Caudinidae and Molpadiidae currently recorded for Australia. Only Molpadiidae was represented in IOT material, with two lots of Molpadia from two stations at 3839 – 4766 m.	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535258FF9AFF36EE27FC6FFAC6.taxon	diagnosis	Diagnosis. (following O’Loughlin et al., 2015, after Pawson, 1977). “ Tentacles claw shaped or with terminal digits and few small lateral digits. Tentacle ampullae long or reduced. Spicules derived from tri-radiate tables with three-pillared spire. Tail with tables with round to oblong disc or long fusiform rods. Phosphatic deposits often present. ” Remarks. Ossicles of some species will gradually transform into light orange or red phosphatic deposits (Pawson et al., 2001). Genera and species within Molpadiidae are differentiated by type or combination of ossicles which include tri-radiate and fusiform tables, fusiform rods, racquets, anchor plates and anchors; and presence or absence of phosphatic deposits (Rowe et al., 2017). Of the three currently accepted genera worldwide, Heteromolpadia and Molpadia have been previously recorded from Australia, with only Molpadia being widespread. We found one Molpadia OTU in the IOT material, Molpadia cf blakei (2 lots).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535259FF9BFC8BED06FB38F8CD.taxon	diagnosis	Diagnosis (see Koehler and Vaney, 1905) Remarks. This family was erected to include animals with a cylindrical body, narrower at the oral end, which have papillae or tube feet exclusively on the two dorsal radii but not on the other three. It currently comprises two genera: Gephyrothuria and Paroriza, previously found off eastern Australia, Gephyrothuria from Queensland to Tasmania and Paroriza from north and east of Tasmania (WoRMS and ALA, January 2024).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535259FF9BFF29E9A3FAB4F993.taxon	materials_examined	Material examined. NMV F 296851 * (3), [IN 2021 V 04 024], NMV F 308219 * (1) [IN 2022 V 08 120]. Diagnosis of IOT material. Cylindrical, mud-filled specimens with pronounced posterior tail and constricted “ neck ”. Body length up to 77 mm long, 32 mm wide and 35 mm high, semi-retracted tail 6 mm long (NMV F 296851, largest specimen, preserved). Brown to light violet or grey. Skin thin and soft, with flat divided longitudinal muscles clearly visible. Tentacles all retracted in these specimens. Body wall ossicles tables with fairly uniform perforated base disc and three-pillared spires, typically over 130 μm high and twisted or fused from halfway. Most tables ~ 100 μm in diameter with six holes (3 large, 3 small) though tables with fewer or greater number of holes also present. Where not broken, spires are topped by a crown of five or more hooks (fig. 29 c). Some shorter spires ~ 60 μm with less-developed hooks (fig. 29 e) also present. Yellow and brown phosphatic deposits seen in tail sample of NMV F 308219. Tail crowded with fusiform ossicles with perforated base disc branching into rods at end, and a three-pillared spire typically shorter than in body wall. Base plate ~ 270 μm with typically six (3 – 8) holes of irregular size. Crown with up to ten hooks but not as curved as in body wall ossicles (e. g. fig. 29 j). Tail ossicles only broken discs and pillars in NMV F 296851. Remarks. TheIOTspecimensweredifferentiatedmorphologically using the key from Pawson (1977). Differentiated from Molpadia musculus by ossicles not being “ almost exclusively ” fusiform tables (including in the body wall), and from those fusiform tables (where present in the tail) being much smaller than the 500 – 1300 μm noted for M. musculus. Some ossicles, particularly from NMV F 296851 are like those in M. liska (Pawson, 1977), but distinguished from that species by having divided muscles and more than four hooks on ossicle spires, and NMV F 308219 also has additional distinguishing characters of phosphatic bodies, fusiform ossicles in tail, and typically more than three perforations in plates. A close match to the body shape, size, colour and skin thickness for the type specimen for M. blakei (68 mm with a 7 mm tail), though while ossicles are visible to the eye, skin in IOT specimens is soft rather than rough. Differs from M. blakei sensu stricto in that six perforations are more common than three perforations, and more than “ a few ” hooks are typical in all pillars including in the tail. Morphologically congruent with Molpadia aff blakei (Théel, 1886) as described by Rogacheva et al. (2013) from the mid-Atlantic ridge, where body wall ossicles with six holes were more prevalent than the discs with three holes as noted in the original description and descriptions of Deichmann (1930, 1940) and Pawson et al. (2001). For COI, the two IOT Molpadia cf. blakei samples have identical COI haplotypes and group with M. musculus (fig. S 3). 16 S sequence data was only available for NMV F 296851 and it again groups with M. musculus. Without additional material for molecular and morphological comparison, we retain our specimens in Molpadia cf. blakei for now, noting the clear morphological differences from M. musculus as diagnosed by Pawson (1977). Distribution. These specimen lots only: Indian Ocean, Australian IOT, Christmas Island and Cocos (Keeling) Islands Territories, Abyss S of Christmas Island Stn. and Rudist Seamount Stn., 3780 – 4766 m. Full bathymetric range. 3780 – 4766 m. References: AFD (2024), ALA (2024), Gebruk et al. (2014), Miller et al. (2017), O’Loughlin et al. (2013, 2015), Pawson (1965), Pawson (1977), Pawson et al. (2001), Rogacheva et al. (2013), Samyn and VandenSpiegel (2016), Smirnov (2012), Théel (1886).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535259FF9BFF29E9A3FAB4F993.taxon	diagnosis	Diagnosis (see Miller et al., 2017) Remarks. Persiculida was erected in 2017 when Miller et al. undertook a major revision of Holothuroidea after molecular evidence showed that three of the five previous orders were nonmonophyletic. Persiculida includes many genera formerly assigned to Synallactidae and Gephyrothuriidae; morphological characters include lack of body wall ossicles and presence of a pygal furrow for which the clade is named (Latin persica = peach, + culus = posterior) (Miller et al., 2017). All three currently accepted families – Gephyrothuriidae, Molpadiodemidae and Pseudostichopodidae – are found in Australia, along with four genera not currently sitting under a family, of which Benthothuria is the only one currently reported from Australia (ALA and WoRMS, 2024). Molpadiodemidae, Gephyrothuriidae and Pseudostichopodidae are reported from the IOT voyages.	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A53525BFF99FF29EBB6FE2DFC80.taxon	diagnosis	Diagnosis (see Hérouard, 1902) Remarks. Paroriza was moved to family Gephyrothuriidae by Miller et al. (2017) as a well-supported sister to Gephyrothuria alcocki, the type-taxon of Gephyrothuriidae. The morphology of the genus differs from the family diagnosis in that only the midventral is completely bare, not the ventrolateral radii. This description also excludes some smaller specimens that have since been noted to have a complete covering of tube feet (Hansen, 1956). There are four currently accepted species worldwide: Paroriza grevei Hansen, 1956, P. pallens (Koehler, 1895), P. prouhoi Hérouard, 1902 and P. verrucosa Massin, 1987. Here we report one lot of P. prouhoi from the IOT at a single station, the first species-level record for the genus in Australia (ALA, 2024). Paroriza is most easily distinguished from Gephyrothuria by being crowded with dorsal appendages rather than having only a few on the dorsal radii, and by being ventrally flattened rather than rounded with a tail (Gephyrothuria has a similar shape to Molpadiidae).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A53525BFF87FF29E81AFDE2FE9B.taxon	materials_examined	Material examined. NMV F 308312 * (1) [IN 2022 V 08 183]. Diagnosis of IOT material. Elongate, subcylindrical specimen, slightly raised dorsally and flattened ventrally, rounded at anterior and posterior ends but otherwise a relatively even width throughout body. Body not obviously curved or tapered and small at 57 mm long, 16 mm wide and 10 mm high (preserved). Skin firm and light brown with a complete dorsal cover of tightly packed white-opaque filiform papillae giving the specimen an almost mauve-grey appearance once preserved. Longer and shorter papillae, slightly more condensed on radii, often with a shorter cylindrical tube foot at the base (fig. 30 e), these are of variable size and scattered throughout. Papillae up to 8 mm long (dorsal, live) and 6 mm long once preserved, shorter on ventrolateral, wide at base tapering to a rounded tip. Papillae and tube feet extend to ventrolateral and encroach on ventral, with cream to light-brown tube feet continuing across the whole ventral surface, smaller along the midventral line. Anus subventral and dark brown with pygal furrow. Mouth ventral with dark brown to purple tentacles, mostly retracted, two visible on thick stalks and with discs with at least five rounded (not bifid) digit-like processes on edges (fig. 30 c). Longitudinal muscles are flat. White and light brown grit caught between papillae and tube feet on surface of the animal. No ossicles present in body wall. Remarks. This IOT specimen is currently distinguished from Paroriza prouhoi Hérouard, 1902 sensu stricto by being noticeably crowded dorsally, and by the presence of midventral tube feet. It also differs from the WoRMS image of a much larger NHMUK specimen of P. prouhoi from the Porcupine Abyssal Plain in the Northeast Atlantic, which is bare midventrally and a lot less crowded dorsally (WoRMS, 2024). We have judged that this discrepancy is due to specimen size, because other morphology including presence of large and small “ tubes ” and dark tentacles and anus match the original description. Hansen (1956), when describing a similar species, P. grevei, noted that while larger specimens were bare midventrally, a covering of ventral tube feet was present in smaller specimens. Here we note the same for our small IOT specimen of P. prouhoi, which is only 57 mm long compared with the type material recorded at 23 cm (Hérouard, 1902). Noting that the IOT specimen is also a perfect match for a genetic sequence of P. prouhoi from the northeast Atlantic, we anticipate a need to revisit species and genus-level descriptions for the group, potentially noting the discrepancies between small and large forms. Distinguished from P. grevei Hansen 1956 by tentacle discs having more than the four diagnostic processes Hansen noted, also less cup shaped. Distinguished from P. pallens by a mixture of long and short tube feet, scattered throughout, rather than uniform and even distribution. Distinguished from P. verrucosa by the presence of a complete dorsal and ventrolateral covering of papillae and scattered tube feet, not just wart-like tube feet, also not smooth or bare ventrally and with different tentacle form. The single P. prouhoi specimen from the IOT was sequenced for COI. The sequence was similar to a previously sequenced P. prouhoi from the northeast Atlantic Ocean, with only two base pair differences (fig. S 4). No other genetic data for other Paroriza species were available at the time of publication. Distribution. North-East Atlantic, off the Azores, the Bay of Biscay, and the Porcupine Seabight; Mediterranean Sea; Indian Ocean (Australian IOT). Full bathymetric range: 3948 – 4880 m (IOT 3948 – 4047 m). Type locality. North Atlantic Ocean between Azores and Portugal, 4360 m. This species not previously recorded from Australia in AFD, and Paroriza only recorded at genus level from Australia in ALA (January 2024). This IOT material extends the geographic range for the species and genus as the first record from the Indian Ocean. It also slightly extends the bathymetric range for the species previously recorded from 4080 m (Gebruk et al., 2014) and is a new record for the species in Australia. References. AFD (2024), ALA (2024), Gebruk et al. (2014), Hansen (1956), Hansson et al. (2001), Hérouard (1902), Massin (1987), WoRMS (2024).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A53525BFF87FF29E81AFDE2FE9B.taxon	diagnosis	Diagnosis. (see Miller et al., 2017) Remarks. This family was erected in 2017 when molecular evidence combined with morphological characters supported its individual status within Persiculida (Miller et al., 2017). It currentlycomprisesasinglecosmopolitangenus: Molpadiodemas, previously found off eastern, southern and north-western coasts of Australia at depths of 528 – 4139 m, and in Australian Antarctic waters (WoRMS and ALA, January 2024).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535245FF87FF29EA0CFE66F8CC.taxon	diagnosis	Diagnosis (following O’Loughlin and Ahearn, 2005, amended for Miller et al., 2017 erection of Molpadiodemidae). Cylindrical body with rounded terminal ends; pygal-furrowed; body surface covered in small discrete tube feet; large prominent tube feet and papillae absent from the paired radii; longitudinal muscles undivided and sit flat against the inner body wall, not cylindrical, broadly attached to the inner body wall; gonad tubules branch out from a common gonoduct base, not in series along the gonoduct; ossicles not found in body wall or tube feet; branched rod ossicles can be present in tentacles, frequently with ends intertwining and side branches fused to create mesh. Remarks. Cosmopolitan genus with a large depth range of 103 – 7086 m (O’Loughlin and Ahearn, 2005). Sixteen species currently accepted worldwide, with only two previously known from Australia: Molpadiodemas crinitus and M. involutus. Others are known from Australian Antarctic waters (AFD, ALA and WoRMS, 2024). The group has traditionally been difficult to split from other pygal-furrowed genera such as Pseudostichopus due to similar external morphology and the lack of truly diagnostic ossicles, with no ossicles in the body wall or tube feet, and those existing in tentacles and gonads being highly variable. The clearest distinguishing feature is flat, broadly attached longitudinal muscles for Molpadiodemas, compared to rounded muscles for Pseudostichopus. O’Loughlin and Ahearn’s (2005) review remains the most comprehensive resource for morphological features, but we found that our species did not fall cleanly into their key as described. Here we report 30 specimen lots of Molpadiodemas from the IOT, with seven lots further diagnosed with genetic support to OTU level as follows: Molpadiodemas sp. MoV. 7329 (3 lots), Molpadiodemas sp. MoV. 7334 (3 lots), Molpadiodemas sp. MoV. 7335 (1 lot). Molecular data confirms the monophyly of Molpadiodemas, but at the time of this study molecular data is only publicly available for four of the 16 currently accepted species. Within Molpadiodemas, our new sequence data forms three distinct lineages. The first lineage, represented here as Molpadiodemas sp. MoV. 7334, contains previously published sequences from M. crinitus (only available for COI), M. morbillus (only available for COI), M. involutus (COI and 16 S), and M. villosus (only available for 16 S). The second lineage, represented here as Molpadiodemas sp. MoV. 7335 has only a single individual (NMV F 296882) from genetically sampled material, and while differing in some internal characters, is superficially like specimens from the third lineage, represented here as Molpadiodemas sp. MoV. 7329 and comprising only IOT samples. While our data increases the available genetic information significantly, more sequencing is needed to assess whether these new lineages correspond to previously described species.	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535240FF83FC93EF93FD02FA06.taxon	diagnosis	Diagnosis (amended from O’Loughlin and Ahearn, 2005, for Miller et al., 2017 erection of Pseudostichopodidae). Characters of Molpadiodemidae (formerly pygal-furrowed Synallactidae): prominent appendages (tube feet, papillae) along the paired radii only; longitudinal muscles cylindrical, not flat, narrowly attached to the body wall; gonad tubules not branched, arising in series along the gonoduct, not from a common base; ossicles sometimes present in tube feet and papillae; tentacle ossicles predominantly unbranched rods, rarely rods with ends intertwining, and side branches fused to create mesh. Remarks. Cosmopolitan genus with 12 currently accepted species worldwide, four of those previously reported for Australia: Pseudostichopus hyalegerus, P. mollis, P. peripatus and P. spiculiferous. Four lots of Pseudostichopus were recorded for the IOT material, identified here to genus level. Pseudostichopus and Molpadiodemas can have a very similar body form. Where tube feet or papillae are obvious on the paired radii this indicates Pseudostichopus, but if these are inconspicuous the only other simple diagnostic feature to split thegeneraiscylindricallongitudinalmusclesin Pseudostichopus (fig. 35 d) compared to flattened and broadly attached ones in Molpadiodemas (fig. 34 a, b). As with Molpadiodemas, ossicles being absent from the body wall and variable in other places make them difficult to use diagnostically without further work. Both sequenced Pseudostichopus from the IOT are genetically within the well-supported Pseudostichopus clade (fig. S 4).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535243FF81FF29EE1FFA7DFEF1.taxon	diagnosis	Diagnosis. (following Hansen, 1975). Tentacles 18 – 20, retractile into the oral cavity; discs with rounded knobs on the margin. Circumoral papillae present. Ossicles perforated plates, consisting of one or several layers of meshwork. Remarks. The taxonomy for the cosmopolitan genus Deima has remained consistent since Hansen’s uniting of the previous six species into one (Deima validum) represented as two subspecies, Deima validum validum Théel, 1879, found worldwide, and Deima validum pacificum Ludwig, 1894, known only from the Gulf of Panama in the eastern Pacific (Hansen, 1975). Six lots of Deima were recorded from the IOT voyages at depths of 1175 – 4990 m, and further identified to: Deima validum validum (4 lots), and one new species Deima oloughlini Mackenzie and Davey sp. nov. (2 lots). The external morphology, clearly retractable tentacles, circumoral papillae and typically a wider oval shape are the easiest features to distinguish Deima from similar-looking animals (Oneirophanta and Orphnurgus) in this family. The Deima samples sequenced form two well-supported genetic clades (D. validum and D. oloughlini Mackenzie and Davey sp. nov.) which are separated by net pairwise distances of 12.7 % for COI and 3.8 % for 16 S (fig. S 5).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535243FF81FF29E8E1FDB2FA84.taxon	diagnosis	Diagnosis (following Hansen, 1975 sensu Ekman, 1926). Ossicles varying from perforated plates and spatulated primary crosses to spatulated, or reduced and deformed rods. Wheels absent. Gonads consisting of few, sac-shaped tubules. Remarks. The Deimatidae are a deep-sea fauna, typically distinctive during surveys due to their clear elliptical to elongated shape, high back with long papillae and flattened base ringed by tube feet. This family comprises three currently accepted genera: Deima Théel, 1879, Oneirophanta Théel, 1879 and Orphnurgus Théel, 1879, all previously known from Australia and represented in the IOT material.	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535243FF8FFC8BEA2BFE05FB2F.taxon	materials_examined	Material examined. NMV F 308224 * (1) and NMV F 308232 (1) [IN 2022 V 08 122]; NMV F 308279 (1) and NMV F 308280 (1) [IN 2022 V 08 151]. Diagnosis of IOT material. Specimens typically pink to white, or white to grey once preserved. Body elliptical to oval, strongly convex dorsally (almost egg-shaped) and flattened ventrally, with a ratio of length to width ~ 5: 3. Specimens up to 90 mm long and 55 mm wide (NMV F 308279, fig. 36 c, d). Long, non-retractile (but often brittle or broken) papillae, in series along each dorsal radii (~ 4 pairs visible, others broken) and in ventrolateral series above tube feet (~ 7 pairs). Anus ventral, almost terminal. Mouth ventral, with retractable tentacles terminating in soft discs, sometimes curled into a cup shape or with rounded or digit-like processes visible. Circumoral papillae present but can be minute or hard to detect. Eleven (9 – 11) pairs of ventrolateral tube feet in single series along each side, smaller at posterior. Some also include smaller post-anal pair (e. g. NMV F 308224, NMV F 308280). No midventral tube feet or pre-anal tube feet observed. Ossicles consist of mostly large, often multilayered perforated plates (fig. 36 e – h), dorsal up to 4.2 mm, ventral up to 1.5 mm, giving a crunchy texture, plus some smaller variable ossicles including dichotomously branching cross-like rods. Two damaged specimens (NMV F 308232 and NMV F 308280) had very broken and imbricating plates visible to the eye. Remarks. Hansen’s (1975) redescription for Deima validum validum Théel, 1879 noted multilayered plates, 10 – 13 pairs of ventrolateral tube feet, rare pre-anal tube feet, and 3 – 7 pairs of lateral papillae, all matching the features of IOT specimens. The description included more dorsal papillae (5 – 10 pairs) than what was seen for IOT specimens, though he noted that these were more variable (Hansen, 1975). All IOT specimens have many multilayered perforated plates identical to the Challenger illustrations from the original type specimens of D. validum (Théel, 1879, pl. 31, figs 4 – 9), which, along with fewer dorsal papillae, distinguished them from the only other subspecies in this genus – D. validum pacificum Ludwig, 1894. They are also clearly differentiated from the two Deima found only at shallower IOT stations less than 2000 m and described below (NMV F 308242 and NMV F 308216). Presence of fewer papillae dorsally along with post-anal tube feet but no pre-anal tube feet in some IOT specimens indicates that our material differs from D. validum validum Théel, 1879 sensu stricto, but we keep it here for now based on the presence of mostly multilayered plates identical to those illustrated in the type material (Théel, 1879). Distribution. Worldwide (though absent from many areas). Full bathymetric range. 724 – 4990 m (IOT 3053 – 4990 m). Type locality (as D. validum). Mid North Pacific Ocean, 3749 m. Subspecies not recorded for Australia in AFD or ALA (January 2024), but D. validum is recorded in both and many species-level records were further identified to subspecies on the NMV catalogue (O’Loughlin, 1998) and published identification lists (O’Hara et al., 2020), making the current Australian range 1250 – 4990 m and slightly extending the worldwide depth range, previously 724 – 4820 m in Gebruk et al. (2014). In Australia this subspecies is now known from Lord Howe Rise, from the eastern abyss off Nowra NSW to just north of Tasmania, from the Great Australian Bight in South Australia and from the Australian IOT. References. ALA and AFD (2024), Gebruk et al. (2014), Hansen (1975), O’Hara et al. (2020), O’Loughlin in NMV Catalogue (1998), Théel (1879).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A53524DFF8DFF29EFE1FAB4FBDE.taxon	description	5 E 9 A 3 B 6925 A 3 sp. MoV. 7322 Material examined. Holotype: NMV F 308216 * (1), [IN 2022 V 08 117] Indian Ocean, Australia, Cocos (Keeling) Islands Territory, IOT: Rudist Seamount (11 ° 19 ' 07 " S – 11 ° 18 ' 28 " S, 99 ° 07 ' 58 " E – 99 ° 09 ' 07 " E), 1175 – 1764 m, Coll: O’Hara et al. Marine Invertebrates Team, RV Investigator, 11 Oct 2022; Paratype: NMV F 308242 * (1), [IN 2022 V 08 131] Indian Ocean, Australia, Cocos (Keeling) Islands Territory, IOT: Cocos (Keeling) (11 ° 49 ' 56 " S – 11 ° 50 ' 37 " S, 96 ° 37 ' 36 " E – 96 ° 38 ' 56 " E), 1589 – 1896 m, Coll: O’Hara et al. Marine Invertebrates Team, RV Investigator, 14 – 15 Oct 2022. Diagnosis. Oval-shaped animal, convex dorsally and flattened ventrally, just over twice as long as wide, white to pink. Ventral mouth with circular field around oral opening, circumoral papillae present, clear marginal knobs on tentacles. Ventral anus. Long tapered papillae, some just short of body width in length, in single rows along dorsal (6 pairs) and ventrolateral (4 – 6 pairs) radii. Ten pairs of ventrolateral tube feet in single rows below papillae, additional post-anal pair of tube feet present behind / above anus, bare midventral apart from present or absent single pair of pre-anal tube feet. Dominant ossicles are irregular perforated plates, typically single layered though occasionally partially imbricating or developing rudimentary secondary layering. Perforations are not uniform, variable in size, shape, number, and position (fig. 37 e – g). Smaller irregular branching structures also present (fig. 37 g). Full descriptions for each specimen below. Holotype. NMV F 308216 (larger specimen). Body oval-shaped, convex dorsally, flattened ventrally, ~ 110 mm long, 52 mm wide and 30 mm high pre-preservation. Dorsoventrally flattened once preserved. Opaque to white, with a pink to orange tinge around tube feet, oral and anal openings. Anus posterior, ventral. Mouth anterior, ventral, and placed in middle of a circular field fringed by obvious circumoral papillae. Tentacles mostly retracted, but ~ 12 visible. Eight well-developed marginal knobs on each tentacle, curled inwards to give the appearance of digits on a hand (fig. 37 d). Ventrolateral tube feet ten pairs, single-rowed, largest mid-body and smallest at posterior. Cylindrical and slightly tapered to rounded end, each capped with a smaller darker end disc. Additional pair of smaller post-anal tube feet present just above / behind the terminal anus, smaller than all ventrolateral tube feet. Two pre-anal tube feet also present on midventral line but lacking any other midventral tube feet. Papillae cylindrical and rigid at base but bending or breaking to flop over and tapering at tip, variable size but largest ~ 40 mm. Dorsal six pairs, ventrolateral six pairs. Dominant ossicles perforated plates, visible to naked eye, some partially imbricating and giving a crunchy ” texture to the dorsal surface. Dorsal ossicle plates are predominantly single layered, variable in size up to 2.1 mm, some with rudimentary branches, knobs, thickening, or anastomosing with a secondary mesh. Thickening and some knobs on plates observed more commonly in perianal samples. Occasionally clustered and imbricating. Perforations are irregular in shape, size, number and placement. Additional ossicles are smaller irregular branching structures up to 0.32 mm that look like individual versions of the initial branches that form multilayers. Ventral with similar single-layered perforated plates to dorsal, but typically smaller (up to 1.5 mm seen here), and often more regular than dorsal plates, with larger perforations clustered towards the centre. Papillae ossicles are elongated and variably curved perforated plates up to 0.8 mm long, some knobbed, thick to thin and branching. Tentacle ossicles thick, straight to curved rods, distally spinous, sometimes centrally bulbous, and up to 0.24 mm long. Paratype. NMV F 308242 (Smaller specimen): Body oval-shaped, convex dorsally, flattened ventrally, ~ 52 mm long and 25 mm wide pre-preservation. Semitransparent, grey to off-white dorsally and pink to orange ventrally. Anus posterior, ventral, almost terminal. Mouth anterior, ventral, and placed in middle of a slightly raised circular field fringed by retracted circumoral papillae. Tentacles retracted other than single exposed disc ~ 4 mm wide with six well-developed marginal knobs (4 larger and 2 smaller tapering digits) visible. Ventrolateral tube feet ten pairs, single-rowed. Cylindrical with dark tips, largest mid-body and smallest at posterior. Additional pair of separate smaller post-anal tube feet present just behind / above the anus, smaller than all ventrolateral tube feet. Midventral tube feet completely absent. Papillae in single rows, rigid, conical, often broken, cylindrical at base and tapering at tip, variable size but largest ~ 22 mm (i. e., nearly full width of body). Dorsal six pairs, ventrolateral approximately four pairs. Dominant ossicles are perforated plates. Dorsal plates predominantly single layered, with some starting to develop additional rudimentary branches or mesh for multilayers. Plates often quite large (e. g. 2.1 mm measured for broken plates – fig. 37 f). Perforations are irregular in shape and size (e. g. 56 – 125 μm for central perforations, with some larger again towards the plate edge) and number. Additional ossicles are rare smaller irregular branching structures. Ventral ossicles are perforated plates like dorsal, but typically smaller (e. g. up to 857 μm, fig. 37 e). Remarks. Deima oloughlini Mackenzie and Davey sp. nov. is morphologically very similar to D. validum validum Théel, 1879 as redescribed by Hansen (1975), only distinguished by reduced typical number of dorsal papillae, a body ratio of just over 2: 1 compared with 5: 3, and most noticeably by a smaller ossicle size range and reduced layering of ossicles, with mostly single-layered rather than multilayered plates with less-uniform perforations. IOT specimens of D. validum validum also appear more domed dorsally than Deima oloughlini Mackenzie and Davey sp. nov. and with thicker, crunchier scales. Deima oloughlini Mackenzie and Davey sp. nov. is distinguished morphologically from D. validum pacificum Ludwig, 1894 chiefly by the reduced number of dorsal papillae, and the inclusion of rudimentary secondary mesh / branching on plates. D. validum pacificum is only known from the eastern Pacific at 1618 – 2487 m, which also makes it unlikely. Hansen (1975) noted that D. validum subspecies have both geographic and bathymetric differences. In Table S 2 we also note distinguishing features between Deima oloughlini Mackenzie and Davey sp. nov., and the species previously synonymised (synonymy retained here) into D. validum validum by Hansen: D. atlanticum Hérouard, 1898, D. blakei Théel, 1886, D. fastosum Théel, 1879, and D. mosaicum Ohshima, 1915. Of these, D. oloughlini Mackenzie and Davey sp. nov. is closest to the West Indian D. blakei, which was noted for typically single-layered perforated plates. The type specimens of D. blakei were collected from a similar depth (1048 – 1115 m) from St Vincent in the Caribbean. The type description is somewhat confused by discussing seven specimens split into two lots of characteristics. Our specimens are both clearly distinguished from four of the type series specimens based on uniform rather than asymmetrical placement of appendages. The remaining three specimens from the type series (which Théel noted as looking more like D. validum) are a closer match to our larger specimen for tube feet and papillae, though Hansen noted an additional pair of papillae for some D. validum (as D. blakei) specimens re-examined from the type location (Hansen, 1975). There is little ossicle detail in the type description for D. blakei, just noting they were perforated plates like Oneirophanta mutabilis, with minimal secondary layering, but Deima oloughlini Mackenzie and Davey sp. nov. differs from the type location material re-examined by Hansen (1975), by typical ossicle size, and perforation shape and placement. Deima oloughlini Mackenzie and Davey sp. nov. ossicle plates are up to 2.1 mm dorsally and 1.5 mm ventrally, compared to 1.5 mm and 1.2 mm for D. validum (as D. blakei), and are also lacking the “ remarkably large ” central perforations of D. blakei, with large and small perforations varying across the plate, particularly in dorsal ossicles. Deima oloughlini Mackenzie and Davey sp. nov. also differs from those D. blakei specimens subsequently reported from other locations as described in the synonymy by Hansen (1975). The high genetic differentiation between Deima oloughlini Mackenzie and Davey sp. nov. and its sister species D. validum (COI: 12.7 %) is in line with accepted genetic differentiation between other sea cucumber species (e. g. Arndt et al., 1996; O’Loughlin et al., 2011; Gubili et al., 2017). While differences in external morphological features are more cryptic with such variability in the genus, the phylogenetic evidence combined with a clear difference in ossicles gives us the confidence to erect Deima oloughlini Mackenzie and Davey sp. nov. here. Etymology. Named in honour of our late mentor and friend, P. Mark O’Loughlin, for his substantial contribution to holothuroid taxonomy, and his willingness to encourage and mentor so many in the field. Distribution. These two specimens only: Indian Ocean, Australian IOT, Cocos (Keeling) Islands Territory, Cocos (Keeling) Stn. and Rudist Seamount Stn. Full bathymetric range. 1175 – 1896 m. References. Arndt et al. (1996), Gubili (2017), Hansen (1975), Hérouard, (1898), O’Loughlin (1998), O’Loughlin et al. (2011), Ohshima (1915), Sluiter (1901 a), Théel (1879 and 1886).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A53524FFF8AFC8BEFF0FDEBFCDF.taxon	diagnosis	Diagnosis. (amended from Hansen, 1975). Tentacles 15 – 20, unretractile; discs usually with rounded knobs on the margin but never with ramified processes. Circumoral papillae absent. Ossicles spatulated crosses or perforated, one-layered plates; spatulated rods typically present in the papillae. Remarks. Bioturbation has been studied in this group, which includes at least one “ conveyor belt ” species (Oneirophanta mutabilis) known to eat and excrete continuously (Moore and Roberts, 1994). It has also been suggested that brood-protection of young occurs in this species (Hansen, 1975). There are three currently accepted species and two subspecies: Oneirophanta conservata, O. mutabilis (with subspecies O. mutabilis affinis and O. mutabilis mutabilis), and O. setigera (WoRMS, 2024). The geographic subspecies division of O. mutabilis has remained since proposed by Hansen (1967), but Rowe et al. (2017) note that the divergence in life history strategies reported by Hansen (1968, 1975) warrant potential treatment at species level. Only O. mutabilis mutabilis (as O. mutabilis) has been previously reported from off the southern and eastern coasts of Australia (ALA, 2024). Six lots of Oneirophanta were recorded from the IOT voyages at depths of 1175 – 5414 m, all further identified to OTU species level as follows: O. mutabilis mutabilis (3 lots), Oneirophanta sp. MoV. 7331 (1 lot), and Oneirophanta sp. MoV. 7333 (2 lots). Morphologically, Oneirophanta is distinguished from Deima by unretractable tentacles, absence of circumoral papillae, and a typically elongate (rather than oval) body. Easily mistaken for Orphnurgus glaber, which can also be elongated and orange / pink with crowded dorsal papillae and large tube feet. As papillae and tube feet arrangement and number are variable across these groups, it is best to separate externally from Orphnurgus by tentacle disc margins (which are ramified / branching in Orphnurgus but typically knobbed in Oneirophanta adult forms) but more accurate to use the dominant ossicle types, which are transformed rods in Orphnurgus compared to perforated plates or spatulated crosses in Oneirophanta. The genus diagnosis from Hansen above was amended to account for spatulated rods being rare or absent in some specimens, as noted in many of his own observations (Hansen, 1975). While Oneirophanta is genetically monophyletic, the relationships between the IOT Oneirophanta samples are incongruent between the COI and 16 S datasets (fig. S 5). In the former, Oneirophanta sp. MoV. 7331 is sister to O. mutabilis mutabilis and Oneirophanta sp. MoV. 7333 is basal to that group. For the latter gene, the relationship between species is unresolved.	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535248FF8AFF36E8F2FC38FA47.taxon	materials_examined	Material examined. NMV F 296855 * (2) and NMV F 296858 * (1) [IN 2021 V 04 028]; NMV F 308159 (2) [IN 2022 V 08 105]. Diagnosis of IOT material. Body robust, elongated, roughly cylindrical. Preserved specimens from IOT are large, up to ~ 24 cm long, 4.5 cm wide and 4.5 cm high (NMV F 296855, largest specimen, preserved). Strongly raised dorsally, flattened ventrally, and rounded to almost square at anterior and posterior ends. Colour orange to pink or white with darker brown or orange tips to tentacles and tube feet, but specimens white when preserved. Body wall firm, skin thick. Dorsal surface crowded with long (2.3 – 11.2 cm long), tapered, non-retractile papillae, making the body wall hard to see. Conspicuous, large (e. g. 3 cm long and 1 cm wide) ventrolateral tube feet in single to paired zigzag series along each side, rare smaller midventral tube feet. Anus terminal, ventral. Mouth terminal, ventral, with 15 – 20 feeding tentacles that never fully retract. Tentacle disc margins with rounded digit-like knobs but not ramified (branching) processes. Ossicles include perforated plates in various stages of development and variably branching rods and crosses, more concentrated in appendages. Perforated plates single layered with larger perforations at the centre and smaller towards the edge, sometimes with small vertical spines and rudimentary mesh forming, sometimes imbricating but not multilayered. As an ossicle size example for the larger IOT specimen NMVF 296855 noted above, plate diameter ~ 0.45 – 0.7 mm (dorsal), ~ 0.48 – 1.5 mm (ventral), 0.6 – 1.1 mm (papillae) and branching rods up to ~ 0.4 mm (tentacle) and ~ 0.46 mm (tube foot). Remarks. Specimens here key morphologically to Oneirophanta mutabilis mutabilis using Hansen’s Galathea Report and descriptions, though he mentions ossicle plates with smaller vertical spines but never a secondary layer of meshwork (Hansen, 1975). We note some very rudimentary mesh here, though agree there is no true multilayering. The original type description (Théel, 1879) also noted that plates can be crowded or imbricating. One smaller specimen (NMV F 308159) had less typical rods and crosses, though plates were still present. Distinguished from Oneirophanta conservata Koehler and Vaney, 1905 by fewer ventrolateral tube feet but more ventrolateral papillae. Distinguished from O. setigera by the presence of perforated plate ossicles. Tentacles have clear marginal knobs, distinguishing them from O. mutabilis affinis. Both sequenced IOT O. mutabilis mutabilis samples form a highly supported clade within the COI phylogeny, with no previous O. mutabilis mutabilis available for comparison (fig. S 5). Distribution. Largely cosmopolitan. Full bathymetric range. 1006 – 6000 m (IOT 2298 – 2850 m). Type locality (as O. mutabilis). Southern Indian Ocean (southeast of South Africa), 2515 m. Subspecies not recorded for Australia in AFD or ALA (January 2024), but many O. mutabilis records were further identified to subspecies O. mutabilis mutabilis in the NMV catalogue, making the Australian range 1006 – 3853 m and extending the shallow limits of the previous known depth range (2515 – 6000 m). In Australia this species is now known from off the eastern coast (north-east Tasmania to the Coral Sea in Queensland), the Great Australian Bight in South Australia, and the Australian IOT. References. ALA and AFD (2024), Bribiesca et al. (2022), Byrne and O’Hara (2017), Gebruk et al. (2014), Hansen (1975), O’Loughlin (1998).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A53524BFF89FC8BE894FB89F8CC.taxon	diagnosis	Diagnosis. (following Thandar, 1992). “ Tentacles 15 – 20, non-retractile, discs with ramified processes. Circumoral papillae absent. Spicules spatulated crosses and / or rods of greatly varying shape, either spatulate, spindle-shaped, smooth with dichotomous ramifications, or spinous, often a combination of two types. ” Remarks. Another charismatic deep-sea megafauna, with IOT samples typically elongated and pink or orange (in life) with prominent papillae and tube feet. The conspicuous dorsal papillae are likely used for respiration (Rowe et al., 2017). Of the nine species known worldwide for this genus, only two have been previously recorded for Australia: Orphnurgus glaber from off the north-west coast, and O. insignis from off the eastern coast, from New South Wales and the Lord Howe Plateau in the Tasman Sea (WoRMS and ALA, 2024). Thirtysix lots of Orphnurgus were recorded from the IOT voyages at depths of 1019 – 2435 m, with lots further identified to OTU species level as follows: O. glaber (13 lots), O. insignis (17 lots), Orphnurgus sp. MoV. 7318 (5 lots), and Orphnurgus sp. MoV. 7332 (1 lot). Distinguished from Deima by unretractable tentacles, absence of circumoral papillae, and a typically elongate (rather than oval) body. Distinguished externally from Oneirophanta by tentacle disc margins (which are ramified / branching in Orphnurgus but only knobbed in Oneirophanta) but more easily by ossicles, which are transformed rods in Orphnurgus compared to perforated plates in most Oneirophanta. Orphnurgus glaber is potentially a species complex (Rowe et al., 2017). The sequenced Orphnurgus from the IOT form three well-supported lineages (fig. S 5). For both the COI and 16 S genealogies, O. glaber and Orphnurgus sp. MoV. 7318 are sister lineages.	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535235FFF7FF29EBB6FAB9F9BC.taxon	materials_examined	Material examined. NMV F 296849 * (1) [IN 2021 V 04 022]; NMV F 296869 * (7) [IN 2021 V 04 035]; NMV F 296874 * (20) [IN 2021 V 04 046]; NMV F 296876 * (7) [IN 2021 V 04 048]; NMV F 308163 (7), NMV F 308164 (1), NMV F 308165 (1) and NMV F 308166 (3) [IN 2022 V 08 108]; NMV F 308168 (17) [IN 2022 V 08 111]; NMV F 308254 * (1) and NMV F 308255 (1) [IN 2022 V 08 141]; NMV F 308299 (1) and NMV F 308300 (2) [IN 2022 V 08 157]. Diagnosis of IOT material. Body elongated, strongly raised dorsally, flattened ventrally, and rounded at ends. Colour salmon-pink to orange or white. White when preserved but often brown or orange at tips of appendages. Body wall smooth, leathery, semitransparent. Papillae variable length, two rows on each dorsal radii plus lateral series above tube feet. Conspicuous, non-retractile ventrolateral tube feet of variable size in single to paired zigzag series along each side (e. g. ~ 24 – 25 each side NMV F 308164). Extended tube feet can be almost same length as papillae but more cylindrical and less tapered at tip, with an obvious dark end disc (fig 41 b). Midventral median line typically visible, mostly bare, sometimes partially scattered to two rows of much smaller tube feet often clearer anteriorly (e. g. ~ 22 midventral, one tenth size of ventrolateral in NMV F 308254). Anus terminal and open. Mouth anterior, ventral, with non-retractile tentacles (~ 18 visible in NMV F 308254). Tentacle disc margins with ramified (branching) processes. Body wall ossicles include smooth rods or spinous rods with solid (rarely flat), thorny ends and / or branched extremities dorsally (fig 41 g – k) often the same but shorter and thicker ventrally (fig 41 l – o). Lacking large ellipsoids, dumbbell-shaped transformed rods or spatulated rods or crosses. IOT specimens small to medium size (e. g. 36 mm long, 7 mm wide, 10 mm high; NMV 296849, preserved) to 60 mm long, 20 mm wide, 10 mm high (NMV F 296869, largest specimen in lot, preserved). Remarks. Hansen synonymised four species into Orphnurgus glaber, made major revisions to the species diagnosis, and applied this to his key for the Orphnurgus genus (Hansen, 1975). Cherbonnier and Féral (1981) subsequently raised O. insignis back out of synonymy and added new species O. bacillus to the genus. Thander (1992) agreed with Cherbonnier and Féral and added two new species, O. aspersignis and O. natalasper. Pawson (2002) added the most recent new species, O. dorisae. These changes make Hansen’s 1975 keys and images for O. glaber unreliable until further investigation can be undertaken. The more recent key (Pawson, 2002) was based only on ossicles and attempted to clarify some of the changes since Hansen (1975), but suggests that spinous rods are absent and spatulate rods present in O. glaber. We note that this is based on Hansen’s amended diagnosis, which at the time nominated spatulated rods as the dominant ossicle for O. glaber, presumably from one of his synonymies because the original description only notes ossicles as “ spinous rods or smooth rods with branched extremities ” (Walsh, 1891). Hanson does not mention re-examining type material to amend this diagnosis. Identifications here are based on Walsh’s (1891) sensu stricto description of O. glaber, with IOT specimens matching the colour, external morphology and ossicles of the type description. Ossicles in IOT specimens are smooth rods with branching or thorny ends but lacking ventral “ fat ” ellipsoid or dumbbell-shaped transformed rods, which agrees with Thander (1992) (sensu Walsh) and Fisher (1907) (referring to Koehler and Vaney, 1905), and with no spatulated rods. Genetics show sampled IOT O. glaber as a new lineage on GenBank, grouping together well but separately from O. glaber previously identified (with limited confidence – NMV catalogue) from northwest Australia (fig. S 5). We identify the IOT material as Orphnurgus glaber Walsh, 1891 sensu stricto, noting that this genus requires further genetic and morphological work to establish clear characters between species. Finally, we report that parasitic Eulimid gastropods (Field number IN 2022 V 08 141 129) were found attached ventrally to specimen NMV F 308254. Distribution. Widely distributed in Indo-west Pacific, recorded from off southern Africa in the Indian Ocean to Hawaii and Tahiti in the Pacific Ocean. Full bathymetric range. 397 – 1553 m (IOT 1019 – 1533 m). Type locality. Bay of Bengal, 1025 m. In Australia this species was not previously recorded in AFD but recorded (identified with limited confidence) from off northwest Australia at depths of 397 – 990 m in ALA (January 2024). These records and IOT material extend the previously known bathymetric range from 700 – 1025 m to 397 – 1553 m, with Australian examples showing the full known depth range of the species, but with the comment that many O. glaber as currently known may need revision. References. AFD (2024), ALA (2024), Cherbonnier and Féral (1981), EOL (2024), Fisher (1907), Hansen (1975), Ohshima (1915), Pawson (2002), Thander (1992), Théel (1879), Walsh (1891).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535235FFF2FC8BED15FA96FE74.taxon	materials_examined	Material examined. NMV F 296867 * (4) and NMV F 296868 * (6) [IN 2021 V 04 035]; NMV F 296871 * (1) [IN 2021 V 04 040]; NMV F 296877 * (3) [IN 2021 V 04 048]; NMV F 308149 (1) and NMV F 308158 (1) [IN 2022 V 08 105]; NMV F 308167 (1) [IN 2022 V 08 108]; NMV F 308169 (1) [IN 2022 V 08 111]; NMV F 308176 (1) [IN 2022 V 08 113]; NMV F 308212 (1) [IN 2022 V 08 117]; NMV F 308239 (1), NMV F 308240 (2), NMV F 308246 (1), NMV F 308247 (1) and NMV F 308248 (1) [IN 2022 V 08 131]; NMV F 308298 * (1) and NMV F 308301 * (2) [IN 2022 V 08 157]. Diagnosis of IOT material. Body elongated, sub-cylindrical, raised dorsally and flattened ventrally. Small to medium-sized (e. g. 3.6 mm long [NMV F 308176] to 11.5 cm long [NMV F 308298, tentacles extended]). Salmon-yellow to pink or orange in colour with yellow-brown tips to appendages. White when preserved. Body wall thin, transparent, often rough ventrally. Papillae typically thin, tapered and in single to zigzag series along each dorsal radii, and in lateral series above the ventrolateral tube feet. Of variable length, larger laterally than dorsally. Some specimens with “ shaggy ” appearance being crowded with papillae, others less so (e. g. 22 or 23 papillae each dorsal radii, and ~ 13 papillae ventrolateral in NMV F 308298, compared to ~ 13 – 15 papillae each dorsal radii, and ~ 9 papillae ventrolateral in NMV F 308301, seemingly not size-dependent). Non-retractile ventrolateral tube feet, ~ 16 – 18 in single to zigzag series along each side. Extended past lateral papillae length in NMV F 308298, but typically shorter, wider, more robust, and less tapered than the papillae. Typically bare of tube feet midventrally, but with median line visible. Anus terminal, slightly dorsal. Mouth terminal but turned to ventral with up to 20 non-retractile tentacles. Tentacles usually quite extended in larger specimens, sometimes with obviously shorter ventral tentacles. Peltate tentacle discs with lobed and ramified (branching) processes on the margins. Dorsal body wall ossicles include smooth, nearly straight rods with branched and sometimes spinous extremities (fig. 42 g – 1). Dominant ventral ossicles (fig. 42 m – x) are thick, transformed rods, variable in shape from ellipsoid to dumbbell or sometimes “ lumpy ” bodies. Visible to the naked eye in smaller specimens (fig. 42 f). Remarks. Hansen’s 1975 synonymy of Orphnurgus insignis with O. glaber was rejected by Cherbonnier and Féral (1981) and subsequent authors. Our identifications here chiefly follow the original description by Fisher (1907) and subsequent examples by Thandar (1992) with smoother branching rods dorsally and thick transformed rods ventrally, though only rare evidence of dorsal cross ossicles was observed (fig 42 l). IOT specimens with less-crowded papillae also match Thander’s (1992) South African variety for papillae distribution. Distribution. Pacific and Indian Oceans including Hawaii, Japan, Philippines, south-east Africa, Australian IOT, off eastern Australia and Tasman Sea. Full bathymetric range. 222 – 2435 m (IOT 1019 – 2435 * m). Type locality. Hawaiian Islands, ~ 222 – 387 m. This species not previously recorded from Australian IOT in AFD (2024) but recorded from at Lord Howe plateau in the Tasman Sea between Australia and New Zealand (1076 – 1147 m), and potentially at upper bathyal depths (<1500 m) off the coast of NSW in ALA (January 2024). This IOT material represents a geographic range extension for the species in Australia. References. AFD (2024), ALA (2024), Cherbonnier and Féral (1981), Fisher (1907), Hansen (1975), Thander (1992).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535232FFF0FC93EAE6FACCF904.taxon	diagnosis	Diagnosis. (following SolÍs-MarÍn, 2003). “ Synallactidae with 15 – 20 tentacles; mouth ventral, anus dorsal, subdorsal or nearly terminal. Skin rather thick. Body with sole-like ventral side, usually with marginal appendages; midventral ambulacrum naked or provided with a few tube feet; ventrolateral ambulacral with tube feet in a single row or more. Dorsally, papillae more or less distinctly in rows. Tube feet well developed ventrolaterally but are often lacking midventrally. Dorsal side with double row of papillae along each radius. Musculature in most cases undivided; genital organs in two tufts, located on both sides of mesentery. Calcareous ring weakly developed, sometimes completely absent. Ossicles: Tables with cross shaped disc and a spire built up of 4 rods, usually with several cross beams; “ C ” shaped bodies maybe present. Ossicles in tentacles, simple or branched rods, sometimes smooth, sometimes spiny. ” Remarks. Cosmopolitan genus with 25 species accepted worldwide, five of which are currently known for Australia: Bathyplotes monoculus, B. moseleyi, B. natans, B punctatus, and B. sulcatus (ALA and WoRMS 2024). Bathyplotes is closely related to Synallactes and can be difficult to distinguish based on external morphology. Distinguished by Bathyplotes having predominantly four-pillared tables ossicles, compared to the single-pillared ones seen in Synallactes. The Bathyplotes sequences included in the COI and 16 S phylogenetic analyses indicate that the genus is paraphyletic and IOT samples exclusively comprise four of the main lineages within the clade (fig. S 5). Interestingly, Synallactes cf. crucifera is highly supported as the sister lineage to the B. moseleyi and B. bongraini group, suggesting an in-depth revision of both genera and likely the family is needed. Specimens here showed similarities to B. moseleyi, B. natans, and B. sulcatus. We have identified tissuesampled specimens to sp. MoV. OTU level and kept others at genus level due to crossover between characters in our specimens and issues with clearly defined morphological and ossicle characters for the species within the genus. Twenty lots of Bathyplotes were recorded from the IOT voyages at depths of 1110 – 1991 m, with 13 lots further identified to OTU species level as follows: Bathyplotes sp. MoV. 7340 (4 lots), Bathyplotes sp. MoV. 7341 (6 lots), Bathyplotes sp. MoV. 7342 (3 lots). One further lot with both Bathyplotes and Synallactes - like characters is identified as Synallactidae sp. MoV. 7339 (1 lot).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535232FFF0FF36EFF1FB34FE2C.taxon	diagnosis	Diagnosis. (adapted from SolÍs-MarÍn, 2003 and Smirnov, 2012 for Miller et al., 2017 erection of Synallactida). Body usually flattened, with a ventral sole with ambulacral feet, dorsal surface with papillae. Head of the stone canal usually in connection with the body wall, sometimes opening outwards through it. Respiratory trees well developed. Tentacular ampullae absent. No Cuvierian organs. Gonad in two tufts, lying to either side of mediodorsal mesentery. Radial muscle bands typically undivided. Stone canal attached to the body wall and sometimes open externally. Calcareous ring can be well-developed, reduced, or altogether absent. Ossicles: tables, rods, sometimes C-shaped bodies, very rarely buttons. Remarks. Cosmopolitan, often seen as an important epibenthic group in abyssal footage, but one of the least-studied deep-sea sea cucumbers (SolÍs-MarÍn, 2005). At the species level, the differences in morphological characters can be quite subtle, obscuring taxonomic distinctions (SolÍs-MarÍn, 2003), and many genera including “ pygal-furrowed ” groups were removed from this family when they were found to be polyphyletic (Miller et al., 2017). Synallactidae is widespread in Australian waters. Of the ten genera now currently accepted worldwide, three have been previously recorded for Australia: Bathyplotes, Paelopatides, and Synallactes. All three are reported here for the IOT material, along with the first record for Scotothuria. Family diagnosis (above) chiefly follows SolÍs-MarÍn (2003) but has been amended to include Smirnov’s (2012) summary of ossicle types, and gonad in two tufts only, following the removal of Mesothuria (one tuft) during the revision by Miller et al. (2017). Future revision may still be required.	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A53523EFFFCFC93EBB6FBD3FAD1.taxon	diagnosis	Diagnosis. (following Martinez et al., 2019 after SolÍs-MarÍn, 2003) “ Body more or less distinctly depressed, with a rather considerable rim surrounding the sides and the extremities. Tentacles 15 – 20, peltate, or sub digitate on margin of the crown. Mouth ventral. Anus dorsal or subdorsal. The tube feet form a double row along the odd ambulacrum, except on the anterior part where they are absent. The papillae form a simple row around the margin of the rim and are scattered along each of the two dorsal ambulacra as well. Interambulacra naked. Gonads on both sides of the dorsal mesentery. A rete mirabile is sometimes present. One or two Polian vesicles. Stone canals apparently lacking. No calcareous ring. Ossicles: Simple tri-radiate or quadri-radiate rods either smooth or spinous; with slightly branched tips; exceptionally deposits often entirely wanting. ” Remarks. Typically large, purple, gelatinous group, with at least one species, Paelopatides retifer reported to swim (Miller and Pawson, 1990). Of the 21 currently accepted species of Paelopatides worldwide, four have previously been recorded for Australia: P. appendiculata, P. aspera (one record only), P. ovalis (one record only), and P. quadridens (WoRMS, ALA and NMV catalogue, 2024). Five lots of Paelopatides are recorded here from the IOT voyages at depths of 2000 – 3839 m and further identified to OTU species level as follows: Paelopatides sp. MoV. 7336 (2 lots), Paelopatides sp. MoV. 7337 (3 lots). The COI sequence data indicates two well-supported Paelopatides lineages that form a clade with IOT Scotothuria herringi (fig. S 5). There is 10.9 % net genetic divergence between the two Paelopatides lineages. Within each Paelopatides lineage, the IOT samples are more closely related to each other than the GenBank sequences from specimens collected in the eastern Pacific Ocean. Only one IOT specimen was sequenced for 16 S. This individual grouped with the same Paelopatides specimen from California, USA as it did in the COI phylogeny. Accurate identification can be difficult in the group due to ossicles often being absent or not diagnostically distinctive, and specimens not maintaining their form when preserved.	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A53523AFFF8FF36ED85FAD8FD18.taxon	diagnosis	Diagnosis. (following Hansen, 1978). “ Synallactidae with dendritic tentacles and with body surrounded by a continuous brim of partly fused podia. Calcareous deposits cross-shaped with arms ending in a cluster of spines and with a central apophysis ending in a hood of downward-bent hooks; spines otherwise arranged in regularly spaced rings along the length of the arms and the apophysis. ” Remarks. Monotypic genus represented by Scotothuria herringi, previously reported from the Atlantic Ocean and from the Indian Ocean off the coast of Kenya. Benthopelagic species typically found swimming above the seafloor by undulating their ventrolateral brim (Gebruk et al., 2014). Some specimens also found to carry parasitic nematodes in their coelom (Billet et al., 1985). Two lots of S. herringi were recorded from two stations on the IOT voyages at depths of 3431 – 5414 m, representing the first records for the genus and species in Australian waters. Prior to these voyages there was only one record of this species being collected by benthic trawl, being most commonly collected in pelagic trawls from 20 to 3900 m above the seafloor (Gebruk et al., 2014).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A53523AFFE6FC93E9B3FD7BF930.taxon	materials_examined	Material examined. NMV F 308231 * (1) [IN 2022 V 08 122]; NMV F 308338 * (1), [IN 2022 V 08 196]. Diagnosis of IOT material. Deep violet to almost black specimens, soft and gelatinous with few features remaining other than some partly fused and some free podia giving a shaggy appearance. Spongey when preserved, some lumps at one end of NMV F 308338 that may have been a damaged mouth, exposed gut, and flat longitudinal muscles. No additional external features observed in these specimens, but type description includes ~ 18 retractile dendritic tentacles and body surrounded by lateral brim of partially fused to wholly embedded podia, plus some minute posterior midventral tube feet. IOT specimens small and damaged, ~ 72 mm long and 26 mm wide (NMV F 308338, pre-preservation) to ~ 95 mm long and 55 mm wide (NMV F 308231, pre-preservation). The larger specimen shrank to ~ 60 mm long on preservation. Dense with distinctive cross-like table ossicles with four arched arms and single tall central spire terminating in palm-tree or umbrella-like hood of downward projecting hooks, some apophyses with pointed tip projecting above this. Umbrella-like hooked structures sometimes also present at further intervals along spire or replaced by rings of reduced spines. Arms also have regularly spaced rings of spines. Apophyses and arms otherwise smooth. Ossicle arm width and spire height are variable (fig. 49 c – h). Second type of ossicle very irregular rods, crosses, and Ys (typically ~ 90 – 130 μm long), covered by rings of spines and terminating in thickened spinous ends (fig. 49 i, k, l). One specimen (NMV F 308231) also has perforated plates, a feature not previously reported for this species. Considering the state of the specimens these might be contaminants, but the sample has at least five plates, of variable shape and size (~ 520 – 1000 μm wide). Shape, number, and size of perforations were also variable, and there were some weak initial indications of secondary layering (fig. 49 j). Remarks. Specimens with few remaining external characters and distinguished almost entirely based on their distinctive ossicle form. While illustrations provided by Hansen (1975) and subsequent images provided by Bohn (2006) of Psychropotes semperiana Théel, 1882 have a similar downward hook-shaped cap to their cross-like ossicles, P. semperiana ossicles are much more spinous and robust, and lack the curved arms and additional circles of hooks present in Scotothuria herringi Hansen, 1978, along with the additional irregular rods, crosses, and Ys noted above. One specimen (NMV F 308338) was from a station with magnesium nodules, which may have led to its slightly darker colour, but both specimens were dark violet to black. Specimens were similar in size to the range given for the types for Scotothuria herringi Hansen, 1978, which were 55 – 85 mm long pre-preservation, shrinking to 48 – 80 mm after (Hansen, 1978). A larger specimen from a subsequent collection was 150 mm pre-preservation, shrinking to 70 mm after (Billet et al., 1985). SolÍs-MarÍn (2003) suggested that similarities with ossicles from Galatheathuria aspera (Théel, 1886 a) might indicate S. herringi is a juvenile of that species, but more taxonomic work is required. Billet et al. (1985) and Miller and Pawson (1990) note that Scotothuria herringi Hansen, 1978 is a possible synonym of Dendrothuria similis (Koehler and Vaney, 1905), but more material from the type localities would be required before any decision on synonymy. Because the distinct “ umbrella-hook ” apophyses were not described in D. similis, we have placed our specimens in S. herring for now, with ossicles being a perfect match for the type material and subsequent work by Billet et al. (1985). While no comparative genetic sequences for Scotothuria were available, the sequences for both Scotothuria examined in this study comprise a well-supported monophyly and form a clade with Paelopatides (fig. S 5). Distribution. Eastern Atlantic and Indian Oceans. Full bathymetric range. 1250 – 5414 m (IOT 1874 – 5414 m). Type locality. North Atlantic Ocean (west of Ireland), collected at 1250 – 1500 m (station depth 5161 m). This species not previously recorded from Australia in AFD or ALA (January 2024). This IOT material represents a geographic and bathymetric range extension for the genus and species, previously with multiple records from the East Atlantic but only a single record from the Indian Ocean off Kenya at 1250 – 4980 m (Gebruk et al., 2014). References. AFD (2024), ALA (2024), Billet et al. (1985), Bohn (2006), Gebruk et al. (2014), Hansen (1978), Koehler and Vaney (1905), Miller and Pawson (1990), SolÍs-MarÍn (2003).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535224FFE4FF36EDE9FBE9FDA6.taxon	diagnosis	Diagnosis. (following SolÍs-MarÍn, 2003 for Synallactes sensu stricto). “ Body cylindrical or sub-cylindrical. Tentacles 18 – 20. Stone canal attached to the body wall. Ventral surface flattened, without any marginal border. Ventral tube feet and dorsal papillae in longitudinal series and confined to ambulacra. On ventral surface, three zones of tube feet. Gonad in two tufts. Body wall ossicles comprise three or quadri-radiate tables, the distal ends of the arms with a larger or smaller number of perforations, and often lateral processes which may unite with similar processes of other arms to produce a complex latticelike network. Spire of a single pillar, which may be terminally divided or perforated, or both. Tube feet with supporting rods. ” Remarks. Of the 26 currently accepted species worldwide (WoRMS, 2024), none are currently recorded for Australia in AFD or ALA (2024), though species are present in Australian (see below) and Australian Antarctic waters (NMV catalogue, 2024). Three lots of Synallactes were recorded from IOT voyages at depths of 2156 – 2418 m, all identified as Synallactes cf. crucifera. Within the Synallactidae, Synallactes and Bathyplotes can have very similar external morphology, particularly when damaged or “ stripped ” during trawls. SolÍs-MarÍn (2005) noted that this has led to past confusion between the species (e. g. Koehler and Vaney, 1905; Heding, 1940) and the introduction of variations in ossicle description. Here we followed SolÍs-MarÍn’s diagnosis above for identification, which specifies single-pillared central spires for Synallactes, compared to the multi-pillared spires with crossbeams as currently known for Bathyplotes. Where the animal or skin is complete, midventral tube feet are also present for Synallactes but not Bathyplotes. Specimens sequenced from this taxon have identical COI and 16 S haplotypes (fig. S 5). For both genes, Synallactes cf crucifera is monophyletic within the genus Bathyplotes and sister to Bathyplotes samples collected in the southern Atlantic and Pacific oceans and Antarctica, indicating the need for a future revision of the group.	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535224FFE4FF36EDE9FBE9FDA6.taxon	materials_examined	Material examined. NMV F 296862 * (2) [IN 2021 V 04 031]; NMV F 308319 * (1) and NMV F 312858 (1) [IN 2022 V 08 187]. Other material. Synallactes cf. crucifer a Perrier, 1898, sensu Rogacheva et al., 2013. – off eastern Australia, NMV F 240992 [IN 2017 V 03 070 123]; NMV F 241034 [IN 2017 V 03 090 106], identified by Mark O’Loughlin (2018). Diagnosis of IOT material. Specimens elongated and sub-cylindrical, ventrally flattened to slightly curved, tapered at oral and anal ends. Body typically salmon-yellow to pink or orange (pre preservation). Where present, thick outer layer of bumpy skin with scattered white wart-like processes in some specimens, but can look flaky, fluffy, or vermiform as the thicker body wall tends to strip off. Where visible, single to double rows of retractable papillae along each dorsal radius, and additional row of shorter, thicker dorsolateral papillae. Papillae conical with whip-like tips. Ventrolateral tube feet and smaller midventral tube feet present, but skin often split along midventral and / or completely stripped. Mouth ventral or directed ventrally, with 18 – 20 tentacles. Anus subdorsal. Example of preserved size: 80 mm long, 25 mm wide, and 8 mm high (NMV F 296862, larger specimen). Body wall with cross-shaped ossicles, typically four-armed (rarely 5 or 6) distally spatulated, and with a single solid, spinous, central spire. Spire of two typical types, short and thick cross type with spire height similar to arm length (56 – 110 μm in these specimens, fig. 50 d – h), and tall and thin cross type with spire approximately three times the arm length (up to 184 μm in these specimens, fig. 50 i). Both types tapered at top, with vertically directed spines running up the spire. Each arm distally flattened and perforated, typically with 1 – 3 larger perforations and three or more smaller, but quite variable and often broken from taller ones. In these samples, dorsal and ventral body walls have predominantly the shorter cross type, papillae have both tall and short types (though longer papillae often dense with the taller version), tube feet have predominantly the shorter cross type, and one papillae sample also has curved rods and rare end plates. No “ tall ” cross types were found in NMV F 308319, but the short type agrees with other specimens. Tentacle ossicles are irregular curved rods, often bifid at ends, sometimes branching. Some smooth rods also observed in body wall. Remarks. Ossicles with some similarities to those figured for Synallactes profundus (pl. 10: fig 19 – 20, Koehler and Vaney, 1905) but differs in body form. Closest to two eastern Australian Synallactes cf crucifera identified by Mark O’Loughlin in 2018 (NMV catalogue; sensu Rogacheva et al., 2013 as per Mark O’Loughlin pers comm.) with mix of tall / thin and short / thick spires and variable numbers of perforations at spatulated ends of arms. Differs from Synallactes crucifera Perrier, 1898 and subsequent diagnosis by Deichman (1940) in having typically more perforations at the ends of arms and no perforations at the tip of the central spire. SolÍs-MarÍn (2003) noted that much Synallactes morphology is similar and more genetic work may be required to refine the species. See genus remarks for current genetic placement of these morphologically congruent Synallactes within Bathyplotes. Distribution. These specimen lots: Indian Ocean, Australian IOT, Cocos (Keeling) Islands Territory, Santa Ridge Stn., Clara Marie Seamount Stn., 2156 – 2418 m. Two comparative specimens noted above: off eastern Australia, New South Wales, Hunter Marine Park and off Byron Bay, 2474 – 2595 m. Full bathymetric range. 2156 – 2595 m. References. AFD (2024), ALA (2024), Deichman (1940), Koehler and Vaney (1905), O’Hara et al. (2020), O’Loughlin (notes and personal correspondence, 2018), Perrier R. (1898, 1902), SolÍs-MarÍn (2003), SolÍs-MarÍn and Laguarda-Figueras (2004), SolÍs-MarÍn (2005).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535226FFE5FC93E978FEF6FB33.taxon	materials_examined	Material examined. NMV F 296846 * (2) [IN 2021 V 04 013]. Diagnosis of IOT material. Medium-sized, elongated, almost cylindrical specimens, slightly flattened ventrally (e. g. 14.5 cm long, 3.5 cm wide, 3 high; preserved). Soft, damaged specimens, firm once preserved, with most skin separated from body. Outer skin salmon pink with white warts and bare body light pink to mauve (live). Skin thick and covered dorsally with white warts and some longer radial papillae (not clear rows). All off-white to grey when preserved. Mouth ventral with approximately five tentacles remaining on one specimen, anus terminal. Tube feet (on shed skin) with zigzag double rows of small outer tube feet (presume ventrolateral), single rows of larger tube feet inside that, and four rows of smaller tube feet (two double rows of zigzags) midventral. Body wall ossicles of various types: typical four-armed tables with multiple perforations at the end of arms (arms ~ 100 μm), though spires not clear; dorsal wall dense with robust four-armed tables ~ 128 μm in diameter, typically with single perforations at ends of arms starting to branch, a short solid central spire ~ 72 μm high and topped with a crown of three bifid teeth; very small four-armed tables with completely joined arms forming button-like discs ~ 33 μm in diameter with four perforations or up to 80 μm with five or more perforations, and spires made of three or more joined pillars ~ 56 μm high and distally spinous. Rare Cs (~ 96 μm), and smooth rods (~ 200 μm). Papillae with four-armed Bathyplotes - style tables with four arms perforated at the ends, distally spinous spire of approximately four pillars with one or two crossbeams towards the top. Robust single-spired tables present in warts / papillae and body wall. Remarks. Damaged specimens but some features available on skin and body. Distinctly different in size and robustness to Bathyplotes and Synallactes species collected in the IOT, though with some similar external characters to Antarctic species B. moseleyi and B. natans, particularly with dorsal covering of white warts and papillae and ventral tube feet being more numerous. Differs from both in ventral tube foot arrangement and in ossicles with thick single-pillared spire more common than typical Bathyplotes spires with pillars joined by transverse beams. Small tables have closed bases like B. punctatus but are very small with fewer than six perforations and irregular spires. While these ossicles and the combination of ossicles and morphology are not known to fit any current species, due to its damaged nature and without more material to identify further, we identify this lot as OTU Synallactidae sp. MoV. 7339. Presence here of numerous robust single-pillared tables (also seen in other IOT Bathyplotes) as the dominant ossicle calls into question the single-pillared table vs multi-pillared table division for Synallactes and Bathyplotes. A revision of the group using morphological and genetic evidence is needed. Distribution. This specimen lot only: Indian Ocean, Australian IOT, Christmas Island Territory, off McPherson Point, 1363 – 1501 m. References. Sars (1868), SolÍs-MarÍn (2003), Sluiter (1901 a), Théel (1886 a).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535227FFE5FF29EFE7FED9F9C0.taxon	materials_examined	Material examined. NMV F 296860 (4) [IN 2021 V 04 028]; NMV F 3308143 (5) [IN 2022 V 08 103]; NMV F 308150 (1), NMV F 308153 (1) and NMV F 308160 (1) [IN 2022 V 08 105]; NMV F 308187 (1) [IN 2022 V 08 115]; NMV F 308233 (1) [IN 2022 V 08 124]; NMV F 308250 (2) [IN 2022 V 08 131]; NMV F 308253 (1) [IN 2022 V 08 136]; NMV F 308256 (3) [IN 2022 V 08 141]; NMV F 308275 (4) [IN 2022 V 08 147]; NMV F 308289 (1) [IN 2022 V 08 153]; NMV F 308302 (1) [IN 2022 V 08 157]; NMV F 308309 (3) and NMV F 308311 (1) [IN 2022 V 08 181]; NMV F 308314 (1) and NMV F 308315 (1) [IN 2022 V 08 183]; NMV F 308322 (1) [IN 2022 V 08 187]. Remarks. Seventeen additional lots were too damaged or incomplete to determine confidently past Holothuroidea for this project.	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A53522DFFEFFF29E9BDFDF8FB22.taxon	materials_examined	Other material. Peniagone azorica Marenzeller von, 1892 – eastern Australian Abyss: NMV F 241035 [IN 2017 V 03 090 110] New South Wales, off Byron Bay (28 ° 40 ' 35 " S – 28 ° 42 ' 32 " S, 154 ° 12 ' 12 " E – 154 ° 11 ' 23 " E), 2562 – 2587 m, Coll: O’Hara et al. Marine Invertebrates Team, RV Investigator, 7 June 2017; NMV F 240855 [IN 2017 V 03 032 143] Victoria, East Gippsland CMR (38 ° 28 ' 44 " S – 38 ° 27 ' 11 " S, 150 ° 11 ' 04 " E – 150 ° 11 ' 10 " E), 3850 – 3853 m, Coll: O’Hara et al. Marine Invertebrates Team, RV Investigator, 24 May 2017. (Identified by Mark O’Loughlin, 2018).	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A53522DFFEFFF29EFF4FD73F902.taxon	description	Peniagone coccinea Rogacheva and Gebruk in Rogacheva et al., 2013 NMV F 296857 (1) [IN 2021 V 04 028] Indian Ocean, Australia, Indian Ocean Territories: Karma Seamount (12 ° 49 ' 33 " S – 12 ° 50 ' 02 " S, 107 ° 02 ' 48 " E – 107 ° 04 ' E), 2760 – 2850 m, Coll: O’Hara et al. Marine Invertebrates Team, RV Investigator, 11 Jul 2021; NMV F 308183 (1), NMV F 308188 (1), NMV F 308189 (2), [IN 2022 V 08 115] Indian Ocean, Australia, Cocos (Keeling) Islands Territory, Indian Ocean Territories: Scrooge Seamount (10 ° 53 ' 45 " S – 10 ° 52 ' 22 " S, 99 ° 45 ' 59 " E – 99 ° 46 ' 38 " E), 2973 – 2974 m, Coll: O’Hara et al. Marine Invertebrates Team, RV Investigator, 10 Oct 2022.	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A53522DFFECFC8BEEBEFD1FFF59.taxon	description	Elasipodida: Elpidiidae: Scotoplanes Théel, 1882	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A53522EFFECFF36EABDFD21FD70.taxon	description	Elasipodida: Laetmogonidae: Benthogone Koehler, 1895	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A53522EFFECFF36EDFFFA52FD62.taxon	description	Elasipodida: Psychropotidae: Benthodytes Théel, 1882	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535228FFEAFF36E912FD2FFC5B.taxon	description	Holothuriida: Mesothuriidae: Zygothuria R. Perrier, 1898	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535228FFEAFF36ED96FA44FE20.taxon	description	Persiculida: Gephyrothuriidae: Paroriza Hérouard, 1902	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535228FFEAFC93EAFAFB7DFD09.taxon	description	Persiculida: Molpadiodemidae: Molpadiodemas Heding, 1935	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535229FFEBFC8BE837FA56FB6C.taxon	description	NMV F 308216 (1), [IN 2022 V 08 117] Indian Ocean, Australia, Cocos (Keeling) Islands Territory, Indian Ocean Territories: Rudist Seamount (11 ° 19 ' 07 " S – 11 ° 18 ' 28 " S, 99 ° 07 ' 58 " E – 99 ° 09 ' 07 " E), 1175 – 1764 m, Coll: O’Hara et al. Marine Invertebrates Team, RV Investigator, 11 Oct 2022; NMV F 308242 (1), [IN 2022 V 08 131] Indian Ocean, Australia, Cocos (Keeling) Islands Territory, Indian Ocean Territories: Cocos (Keeling) (11 ° 49 ' 56 " S – 11 ° 50 ' 37 " S, 96 ° 37 ' 36 " E – 96 ° 38 ' 56 " E), 1589 – 1896 m, Coll: O’Hara et al. Marine Invertebrates Team, RV Investigator, 14 – 15 Oct 2022. Synallactida: Deimatidae: Oneirophanta Théel, 1879	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A53522BFFD6FC8BED95FD3DFE2E.taxon	description	Synallactida: Synallactidae: Synallactes Ludwig, 1894	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
432A0A535214FFD6FC93EAE1FA4DFD7D.taxon	description	NMV F 296860 (4) [IN 2021 V 04 028]; NMV F 3308143 (5) [IN 2022 V 08 103]; NMV F 308150 (1), NMV F 308153 (1) and NMV F 308160 (1) [IN 2022 V 08 105]; NMV F 308187 (1) [IN 2022 V 08 115]; NMV F 308233 (1) [IN 2022 V 08 124]; NMV F 308250 (2) [IN 2022 V 08 131]; NMV F 308253 (1) [IN 2022 V 08 136]; NMV F 308256 (3) [IN 2022 V 08 141]; NMV F 308275 (4) [IN 2022 V 08 147]; NMV F 308289 (1), [IN 2022 V 08 153]; NMV F 308302 (1) [IN 2022 V 08 157]; NMV F 308309 (3) and NMV F 308311 (1) [IN 2022 V 08 181]; NMV F 308314 (1) and NMV F 308315 (1) [IN 2022 V 08 183]; NMV F 308322 (1) [IN 2022 V 08 187].	en	Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo, Haines, Margaret L. (2024): A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea). Memoirs of Museum Victoria (Mem. Mus. Vic.) 83: 207-316, DOI: 10.24199/j.mmv.2024.83.03, URL: https://doi.org/10.24199/j.mmv.2024.83.03
