Oneirophanta stet. CCZ_100

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

Oneirophanta stet. CCZ_100

Fig. 40

Material.

Clarion-Clipperton Zone • 1 specimen; APEI 4; 7.2647°N, 149.774°W; 3550 m deep; 03 Jun. 2018; Smith & Durden leg.; GenBank: ON400706 (COI), ON406643 (18S), ON406620 (16S); NHMUK 2022.84; Voucher code: CCZ_100 .

Description.

Single specimen; colouration of live specimen is beige, spotted with light brown and yellow on dorsal surface (Fig. 40A, C, D ), and lighter on ventral surface, with suckers on tube feet and tentacles being dark brown (Fig. 40D ). Body cylindrical, ~ 33 cm long and 8.8 cm wide; mouth anteroventral, anus posteroventral. Tentacles partly retracted. Papillae arranged in one or two rows along the dorsal radii, and in a single row along the ventrolateral radii above the tube feet. Tube feet ~ 50 pairs, arranged in two or three rows on each ventrolateral ambulacrum; few tube feet located along mid-ventral ambulacrum, among them two tube feet, one placed approx. half the body length and the other approx. three quarter of the body length; and few smaller feet close to anus. Dorsal ossicles spatulated crosses, crosses with open ramifications, and small irregular perforated plates; ventral ossicles crosses with open ramifications of different stage of development.

Remarks.

Closest match for COI and 16S sequences is to Oneirophanta setigera (Ludwig, 1893) (86.7% and 96.3%, respectively). In the phylogenetic tree, it is recovered in a well-supported clade representing the family Deimatidae , including Oneirophanta (Fig. 34 ). According to the external morphology Oneirophanta sp. CCZ_100 differs from Oneirophanta mutabilis mutabilis Théel, 1879, O. mutabilis affinis Ludwig, 1893 and O. conservata Koehler & Vaney, 1905 in high number of tube feet arranged in two or three rows and by absence of large, perforated plates on dorsum. It differs from O. setigera in high number of tube feet arranged in two or three rows and by presence of small, perforated plates and bigger perforations on spatulated crosses.

Ecology.

The specimen was found on the sediment seafloor of a seamount on APEI 4 at 3550 m depth.

Comparison with image-based catalogue.

No exactly similar Deimatidae morphotypes have been so far catalogued from seabed imagery collected in the eastern CCZ nor in abyssal areas of the Kiribati EEZ. Consequently, the in situ image of CCZ_100 was catalogued as a new morphotype (i.e., Oneirophanta sp. indet., HOL_063). However, HOL_063 could be potentially confused with a similar shaped Deimatidae morphotype (e.g., Deimatidae gen. indet., HOL_062; also beige, cylindrical, with conspicuous projections on the dorsal surface arranged in four rows) found in the eastern CCZ (e.g., Amon et al. 2017b), with more abundant -though slightly thinner- projections, that may be difficult to distinguish in vertically facing images.

Figures

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.

Figure 40. Oneirophanta stet. CCZ _ 100 A dorsal view of specimen before preservation B in situ image C ventral view D dorsal ossicles E ventral ossicles. Scale bars: 2 cm (A, C); 5 cm (B); 200 μm (D); 100 μm (E). Image attribution: Wiklund, Durden, Drennan, and McQuaid (A, C); Durden and Smith (B); Kremenetskaia (D, E).