Kamptosoma abyssale Mironov, 1971

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

Kamptosoma abyssale Mironov, 1971

Fig. 33

Material.

Clarion-Clipperton Zone • 1 specimen; APEI 4; 7.036°N, 149.9395°W; 5040 m deep; 01 Jun. 2018; Smith & Durden leg.; GenBank: ON400701 (COI); CASIZ 229306; Voucher code: CCZ_082 .

Other material.

Pacific Ocean • 1 specimen, holotype of Kamptosoma asterias (A. Agassiz); off the coast of Chile; 33.5167°S, 74.7167°W; 3950 m deep; Challenger Expedition, Stn. 299; NHMUK 1881.11.22.114. • 2 specimens, Kamptosoma abyssale Mironov, 1971; Tasman Sea; 0°N, 0°E; 4850- 4800 m deep; Galathea Expedition, Stn. 574; NHMUK 1984.1.25.86-87 .

Description.

Single specimen (d = 3.4 cm, H = 1.6 cm). In situ, the body is reddish brown, rounded and flattened (Fig. 33A, B ). Spines are the same reddish brown colour of the body; oral primary spines are encased by a fleshy, clear sac, swollen and brighter at the tip. The test and covering skin are very thin and gonads are visible through; primary spines are projected upwards and tube feet extending downwards from the lower half of the body. Whole abactinal surface (ambulacral and interambulacral) covered by primaries arranged in irregular lines along the median lines of the plates, with few secondaries or militaries near ambitus (Fig. 33C ). Claviform (globiferous) pedicellariae carries two saccules and two valves. Before preservation, colouration was bright orange.

Remarks.

Only two species of Kamptosoma have been described to date. Kamptosoma asterias (Agassiz, 1881) was first described from off the coast of Chile at 3950 m depth (type locality: H.M.S Challenger St. 299), and from the east of Malden Island, Central Pacific, at 4750 m depth (type locality for K. indistinctum synonymous with K. asterias : H.M.S. Challenger St. 272) ( Agassiz 1881; 1904). It has also been reported for the central Pacific Ocean, the Tasman Sea, Chile, Antarctica, and the southern Indian Ocean from 3890-4950 m depth ( Anderson 2016). Kamptosoma abyssale type locality is the Kuril-Kamchatka Trench, from 6090-6235 m ( Mironov 1971), and occurs in the Northwest Pacific, from Aleutian Islands to Kermadec Trench, and from Madagascar to east of Hawaii between 4374-6235 m depth ( Mooi et al. 2004). These two species are only differentiated by the shape of the claviform pedicellaria (previously referred to as globiferous pedicellaria, but Mironov et al. (2015) suggested these to belong to the claviform group as their rudimentary valves are not functional), with two valves in K. abyssale , and three valves in K. asterias . The specimen from the CCZ has pedicellariae with two saccules and two valves, as described for K. abyssale . However, the COI sequence is very similar (0.47-1.4% K2P distance) to sequences of K. asterias collected in the Tasman Sea from 4570-4744 m depth, and are recovered in a well-supported clade (Fig. 31 ). These values of genetic divergence are within the intraspecific divergence that has been reported for echinoids ( Chow et al. 2016), and therefore might belong to the same species. Nonetheless these specimens identified as K. asterias were reported to have claviform pedicellariae with two valves as described for K. abyssale ( Anderson 2016). It has been suggested that K. abyssale is a synonym of K. asterias , and the former species will only be validated once material from both type localities is examined in detail ( Anderson 2016; Mironov et al. 2015; Mooi et al. 2004). Kamptosoma asterias from the Central Pacific (St. 272) has been re-examined and was reported to have pedicellariae with three valves ( Mironov et al. 2015). The holotype from St. 299 was examined in this study. Unfortunately, most pedicellariae have been lost and only a single claviform pedicellariae was found, this with two valves.

Ecology.

The specimen was found crawling rapidly across abyssal sediment in APEI 4, at 5040 m depth. This morphotype has an unusually high crawling speed.

Comparison with image-based catalogue.

A very similar Kamptosoma sp. morphotype (i.e., Kamptosoma abyssale sp. inc., URC_010) has been encountered in seabed image surveys conducted in abyssal areas of Kiribati’s EEZ, but not in the eastern CCZ. URC_010 was the most abundant echinoid morphotype encountered in the abyssal areas explored within Kiribati’s EEZ ( Simon-Lledó et al. 2019d).

Class Holothuroidea

Holothurians are important components of the benthic deep-sea megafauna, and currently there are 367 records at a minimum depth of 3000 m in the CCZ, with 141 representing preserved specimens ( OBIS 2022). Holothurians are amongst the most diverse invertebrate megafaunal taxa in the CCZ seafloor; a total of 106 different holothurian morphotypes has been so far catalogued in the image-based assessments consulted for this study, across the CCZ and nearby locations. We collected 18 specimens belonging to 15 different species, for which the COI gene was successfully amplified for all but one specimen. The gene 18S was successfully amplified for that specimen, as well as for other three. These were included in a concatenated alignment (12S, 16S, 18S, 28S, COI, and H3) used to estimate a phylogenetic tree (Fig. 34 ).

Subclass Actinopoda Ludwig, 1891

Order Persiculida Miller, Kerr, Paulay, Reich, Wilson, Carvajal & Rouse, 2017

Family Molpadiodemidae Miller, Kerr, Paulay, Reich, Wilson, Carvajal & Rouse, 2017

Figures

Figure 31. Phylogenetic tree of Echinoidea. COI-only median consensus BEAST 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 33. Kamptosoma abyssale Mironov, 1971. Specimen CCZ _ 082: A, B in situ images C oral view D aboral view of specimen before preservation. Scale bars: 1 cm (A, B); 5 mm (C, D). Image attribution: Durden and Smith (A, B); Wiklund, Durden, Drennan, and McQuaid (C, D).

Figure 34. Phylogenetic tree of the class Holothuroidea. Concatenated (12 S, 16 S, 18 S, 28 S, COI, and H 3) median consensus BEAST 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.