Catherinum cf. novaezelandiae (Hoek, 1883)

Bribiesca-Contreras, Guadalupe, Dahlgren, Thomas G., Amon, Diva J., Cairns, Stephen, Drennan, Regan, Durden, Jennifer M., Eleaume, Marc P., Hosie, Andrew M., Kremenetskaia, Antonina, McQuaid, Kirsty, O'Hara, Timothy D., Rabone, Muriel, Simon-Lledo, Erik, Smith, Craig R., Watling, Les, Wiklund, Helena & Glover, Adrian G., 2022, Benthic megafauna of the western Clarion-Clipperton Zone, Pacific Ocean, ZooKeys 1113, pp. 1-110 : 1

Catherinum cf. novaezelandiae (Hoek, 1883)

Fig. 7

Material.

Clarion-Clipperton Zone • 1 specimen; APEI 1; 11.2751°N, 153.7444°W; 5241 m deep; 09 Jun. 2018; Smith & Durden leg.; GenBank: ON400722 (COI), ON406625 (18S); WAM C74111 ; Voucher code: CCZ_185 .

Description.

Single specimen 14 mm long; with elongated, white capitulum,> 2 × as long as wide (L = 12 mm, W = 5 mm), and short peduncle (2 mm) with small scales (Fig. 7 ). Capitulum consists of 14 fully calcified capitular plates with growth lines, separated from each other by narrow chitinous sutures. Carina is simply bowed, with flat roof. Tergum is triangular, shorter on the occludent margin, with apical umbo; apical angle is similar to angle between the carinal and scutal margins. Upper latus somewhat pentagonal, with lower edge truncated, and apical edge reaching over the scutum; with apical umbo. Rostrolatus with umbo apical on the rostral margin, and arched lateral margin. Inframedian latus irregular in shape, narrow, almost 3 × as long as the widest part, with umbo sub-medial; rostral and carinal margins concave. Carinolatus is large, ~ 2 × as long as wide, with umbo sub-carinal, above basal angle.

Remarks.

Morphological characters of the capitulum conform to the description of the genus Catherinum . The sequence for the 18S gene is similar to sequences from other species within the same family. Another species within the genus, C. tortilum (Zevina, 1973), originally described from the Indian Ocean at 2760 m depth has also been recorded for the CCZ at similar depths (4872-4877 m depth; Poltarukha and Mel’Nik 2012). In C. tortilum , the inframedian latus’ umbo is conspicuously displaced laterally away from the midline. The species C. novaezelandiae is distributed in the Western and Eastern Indian Ocean, Western Central and Southwest Pacific, from depths 455-4800 m ( Shalaeva and Boxshall 2014), but was originally described from East Cape, New Zealand (Southwest Pacific), at 1280 m.

Ecology.

The specimen was collected in the sedimented abyssal plain of APEI 1 at 5241 m depth. It was attached to a glass sponge stalk, along with a crinoid ( Bathymetrinae inc. CCZ_176; specimen CCZ_186), a polychaete, and anemones, that was anchored in the mud.

Comparison with image-based catalogue.

Relatively large abundances of a very similar morphotype ( Catherinum sp. indet., ART_031) were observed in seabed imagery collected within abyssal areas of the Kiribati EEZ, but not in eastern CCZ surveys.

Phylum Cnidaria Hatschek, 1888

A total of 12 cnidarians w collected, belonging to six orders in two classes ( Anthozoa and Scyphozoa).

Class Anthozoa Ehrenberg, 1834

Subclass Hexacorallia Haeckel, 1896

Order Actiniaria Hertwig, 1882

To date, there are 33 records of Actiniaria found at> 3000 m depth in the CCZ ( OBIS 2022), but only two of these represent collected specimens. We collected five specimens, all belonging to different species, and for which genetic sequences of the COI or 18S genes were generated and included in a phylogenetic tree built from a concatenated alignment of 12S, 16S, 18S, 28S, COI, and COX3 (Fig. 8 ).

Suborder Enthemonae Rodríguez & Daly in Rodríguez et al. 2014

Superfamily Metridioidea Carlgren, 1893

Metridioidea stet. CCZ_072

Fig. 9

Material. Clarion-Clipperton Zone • 1 specimen; APEI 1; 5.0442°N, 141.8165°W; 4875 m deep; 28 May. 2018; Smith & Durden leg.; GenBank: ON400696 (COI); NHMUK 2021.19; Voucher code: CCZ_072.

Description. Single specimen, white (Figs 5 , 9 ). Body subcylindrical, pedal disc modified and attached to a glass sponge stalk, oral disc is> 2 × column width; with at least two cycles of slender, tapered, long, white tentacles, almost as long as the oral disc diameter (Fig. 5A ). Tubercles are evident on the top half of the column when preserved, but tentacles completely retracted (Fig. 9 A, B ).

Remarks. COI sequence is similar (97.3%) to other species within the subfamily Metridioidea but based on COI we were unable to delimit species because interspecific divergence is very low. Additionally, only a few studies have included sequences for COI, therefore hindering comparisons based solely on this gene. The COI divergence between Metridiodea stet. CCZ_164 and Metridiodea stet. CCZ_072 (1.95% K2P distance) was higher than the genetic distance between other species in the family Metridiodea ( Rodriguez et al. 2014), suggesting these to belong to separate species. The phylogenetic tree recovered both CCZ specimens within the subfamily Metridioidea (Fig. 8 ), in a clade belonging to Cuticulata. Clades within Cuticulata were not well resolved in the phylogeny, but this group includes the Graspina clade (families Amphiantidae , Galantheanthenidae , and Actinoscyphiidae ) that is characterised by a modified pedal disc that enables them to attach to other substrates, such as sponge stalks ( Rodriguez et al. 2014), and is advantageous in deep-sea ecosystems. Based on this modified pedal disc, the specimen very likely belongs to a family within the Graspina clade.

Ecology. The specimen was collected in a muddy abyssal plain in APEI 7, at 4874 m depth. It was attached to a glass sponge stalk (Fig. 5A ; top of stalk), along with two barnacles ( Catherinum cf. albatrossianum , specimen CCZ_073; and Trianguloscalpellum gigas , specimen CCZ_074).

Comparison with image-based catalogue. A very similar Actiniaria morphotype ( Metridioidea fam. indet., ACT_042) mostly attached to sponge stalks, has been commonly encountered in seabed image surveys conducted across the eastern CCZ but not in abyssal areas of the Kiribati EEZ.

Metridioidea stet. CCZ_154

Fig. 10

Material. Clarion-Clipperton Zone • 1 specimen; APEI 4; 6.9702°N, 149.9426°W; 5009 m deep; 06 Jun. 2018; Smith & Durden leg.; GenBank: ON400715 (COI); NHMUK 2021.27; Voucher code: CCZ_154.

Description. Single specimen, completely white when alive (Fig. 10 ). Body of live specimen is more or less cylindrical, wider proximally and distally, 29 mm long. Pedal disc is the widest, 35 mm in diameter, attached to a manganese nodule, and oral disc 24 mm in diameter (Fig. 10B ). Large and small conical, tapered tentacles alternating on the margin of the oral disc in two cycles: ~ 20 + 20, with the larger ones being approx. half the oral disc diameter and located above the smaller tentacles (Fig. 10A ). Tentacles are only visible in in situ images (Fig. 10A ), as they are fully retracted in the preserved specimen.

Ecology. This specimen was attached to a nodule in abyssal sediments in APEI 4 at 5009 m depth.

Remarks. The COI sequence is similar to sequences of species within different families, but in the phylogenetic tree it is recovered within the superfamily Metridioidea (Fig. 8 ).

Comparison with image-based catalogue. No similar Actiniaria morphotypes had been catalogued so far from seabed imagery in the eastern CCZ or in abyssal areas of the Kiribati EEZ. The in situ image of Metridiodea stet. CCZ_154 was hence catalogued as a new morphotype (i.e., Metridioidea fam. indet., ACT_044).

Metridioidea stet. CCZ_164

Fig. 11

Material. Clarion-Clipperton Zone • 1 specimen; APEI 7; 6.988°N, 149.9326°W; 5001 m deep; 06 Jun. 2018; Smith & Durden leg.; GenBank: ON400717 (COI); NHMUK 2021.5; Voucher code: CCZ_164

Description. Single specimen, white (Fig. 11A ). Specimen with a short, subcylindrical column, with pedal and oral discs almost the same diameter (Fig. 11A ). Long, slender, tapered, white tentacles arranged in at least two cycles (Fig. 11A ). When preserved, column is more cylindrical, almost as long as wide (H = 18 mm, oral disc diameter = 21 mm), and tubercles are evident on the top half of the column; tentacles completely retracted (Fig. 11B, C ).

Remarks. COI sequence is very similar to Metridiodea sp. CCZ_072 and they are recovered as sister species, in the multi-gene phylogeny, within the Cuticulata in the superfamily Metridioidea (Fig. 8 ). This species very likely belongs to a family within the Graspina clade ( Amphiantidae , Galantheanthenidae and Actinoscyphiidae ) based on the modified pedal disc that allows them to attach to substrates other than rocks ( Rodriguez et al. 2014).

Ecology. This specimen was collected in muddy abyssal sediments in APEI 4 at 5001 m depth, attached to a glass sponge stalk.

Comparison with image-based catalogue. As with specimen from Metridiodea stet. CCZ_072, a very similar morphotype has been commonly found in seabed image surveys conducted across the eastern CCZ (i.e., Metridioidea fam. indet., ACT_042), but it does not seem possible to differentiate between the species Metridiodea stet. CCZ_072 and Metridiodea stet. CCZ_164 from in situ imagery. Morphotype ACT_042 is hence likely to encompass, at least, these two species in image-based analyses conducted across the CCZ.

Superfamily Actinostoloidea Carlgren, 1932

Family Actinostolidae Carlgren, 1932

Actinostolidae stet. CCZ_183

Fig. 12

Material. Clarion-Clipperton Zone • 1 specimen; APEI 1; 11.2751°N, 153.7444°W; 5241 m deep; 09 Jun. 2018; Smith & Durden leg.; GenBank: ON406626 (18S); NHMUK 2021.28; Voucher code: CCZ_183.

Description. Single specimen, white, attached to a nodule (Fig. 12A ). Column is very short (3 mm), cylindrical (6 mm diameter), pedal disc much wider and completely attached to the nodule. Small tubercles scatter on the column (Fig. 12B ).

Remarks. Closest matches for the 18S sequence are sequences from other members of the family Actinostolidae (> 99.3%). In the phylogenetic tree, it is also recovered in a well-supported clade with species of the family Actinostolidae (Fig. 8 ). However, this clade also includes Capnea , which has been recovered within the same clade in previous studies ( Rodriguez et al. 2014), and a specimen collected in the eastern CCZ identified as a member of the family Hormathiidae ( Hormathiidae sp. NHM_416, Dahlgren et al, 2016). No in situ photos are available.

Ecology. This specimen was collected in abyssal sediment in APEI 1 at 5241 m depth, attached to a polymetallic nodule.

Actinostolidae stet. CCZ_202

Fig. 13

Material. Clarion-Clipperton Zone • 1 specimen; APEI 4; 11.2518°N, 153.6059°W; 5206 m deep; 10 Jun. 2018; Smith & Durden leg.; GenBank: ON406627 (18S); NHMUK 2021.22; Voucher code: CCZ_202.

Description. Single, white specimen (Fig. 13A ). Specimen with short column (4 mm), pedal and oral disc approx. the same diameter (8 mm). Between 8-10 white, long tentacles, approx. as long as the oral disc diameter (Fig. 13A ). Column with scale-like pattern in preserved specimen (Fig. 13B ), with tentacles fully retracted.

Remarks. The closest matches to the 18S sequence are species in different suborders within the Actiniaria (98.3% sequence similarity), including Hormathiidae sp. NHM_416 from the CCZ ( Dahlgren et al. 2016). However, in the phylogenetic tree it is confidently recovered within the Actinostolidae (Fig. 8 ), along with the specimen Hormathiidae sp. NHM_416.

Ecology. This specimen was attached to a polymetallic nodule collected in abyssal sediments of APEI 1 at 5206 m depth.

Comparison with image-based catalogue. No similar Actiniaria morphotypes have been so far catalogued from seabed imagery in the eastern CCZ or in abyssal areas of the Kiribati EEZ. The in situ image of Actinostolidae stet. CCZ_202 was hence catalogued as a new morphotype (i.e., Actinostolidae gen. indet., ACT_080). However, small actiniarians (e.g., oral disc <2 cm) are usually difficult to classify from seabed imagery as basic morphological features (e.g., number of tentacles) are often not clearly visible. Consequently, ACT_080 could be potentially confused with similarly small actinian morphotypes commonly encountered in the eastern CCZ (i.e., Hormathiidae gen. inc., ACT_022, also with a short pedal approx. the same diameter as the oral disc, but with 16-18 long thin tentacles).

Order Scleractinia Bourne, 1900

For Scleractinia , there are only two records at> 3000 m depth in the CCZ ( OBIS 2022), with no specimens collected. A single scleractinian was collected, for which DNA amplification was unsuccessful.

Family Fungiacyathidae Chevalier & Beauvais, 1987

Figures

Figure 5. Trianguloscalpellum gigas (Hoek, 1883). Specimen CCZ _ 074: A in situ photograph, attached to a glass sponge stalk B left C and right lateral views. Scale bars: 5 cm (A); 1 mm (B, C). Image attribution: Durden and Smith (A), Hosie (B, C). Arrows indicate position of T. gigas (specimen CCZ _ 074; lower, yellow) and Catherinum cf. albatrossianum (specimen CCZ _ 073; upper, green).

Figure 7. Catherinum cf. novaezelandiae (Hoek, 1883). Specimen CCZ _ 185: A in situ photograph B right C left lateral views. Scale bars: 1 cm (A); 1 mm (B, C). Image attribution: Durden and Smith (A), Hosie (B, C).

Figure 8. Rooted Bayesian phylogeny of Actiniaria. Concatenated (12 S, 16 S, 18 S, 28 S, COI, and COX 3) BEAST median consensus tree with posterior probability (PP) and bootstrap (BS) values indicated. Only values of PP> 0.70 and BS> 50 are shown, with values of PP> 0.95 and BS> 90 indicated with a circle. Nodes not recovered on the RAxML tree are indicated with a hyphen. Sequences generated in this study are highlighted in violet.

Figure 9. Metridioidea stet. CCZ _ 072 A oral B lateral views. Scale bars: 5 mm (A, B). Image attribution: Wiklund, Durden, Drennan, and McQuaid (A, B).

Figure 10. Metridioidea stet. CCZ _ 154 A in situ image B specimen before preservation. Scale bars: A, B 1 cm. Image attribution: Durden and Smith (A), Wiklund, Durden, Drennan, and McQuaid (B).

Figure 11. Metridioidea stet. CCZ _ 164 A in situ image of specimen CCZ _ 164 B detail of oral disc C lateral view of specimen. Scale bars: 2 cm (A); 2 mm (B); 5 mm (C). Image attribution: Durden and Smith (A), Wiklund, Durden, Drennan, and McQuaid (B, C).

Figure 12. Actinostolidae stet. CCZ _ 183 A specimen attached to nodule B close-up of specimen. Scale bars: 1 cm (A), 2 mm (B). Image attribution: Wiklund, Durden, Drennan, and McQuaid (A, B).

Figure 13. Actinostolidae stet. CCZ _ 202 A in situ image B detail of specimen. Scale bars: 1 cm (A); 1 mm (B). Image attributions: Durden and Smith (A), Wiklund, Durden, Drennan, and McQuaid (B).