Benthic megafauna of the western Clarion-Clipperton Zone, Pacific Ocean Author Bribiesca-Contreras, Guadalupe https://orcid.org/0000-0001-8163-8724 Life Sciences Department, Natural History Museum, London, UK l.bribiesca-contreras@nhm.ac.uk Author Dahlgren, Thomas G. https://orcid.org/0000-0001-6854-2031 Department of Marine Sciences, University of Gothenburg, Gothenburg, Sweden & Norwegian Research Centre, NORCE, Bergen, Norway Author Amon, Diva J. SpeSeas, D'Abadie, Trinidad and Tobago Author Cairns, Stephen https://orcid.org/0000-0001-7209-9271 Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, D. C., USA Author Drennan, Regan https://orcid.org/0000-0003-0137-5464 National Oceanography Centre, Southampton, UK Author Durden, Jennifer M. https://orcid.org/0000-0002-6529-9109 UMR ISYEB, Department Origines et Evolution, Museum national d'Histoire Naturelle, Paris, France Author Eleaume, Marc P. Collections & Research, Western Australia Museum, Perth, Australia Author Hosie, Andrew M. https://orcid.org/0000-0002-5683-662X Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia Author Kremenetskaia, Antonina https://orcid.org/0000-0001-8851-3318 School of Biological and Marine Sciences, University of Plymouth, Plymouth, UK Author McQuaid, Kirsty https://orcid.org/0000-0002-0395-8332 Museums Victoria, Melbourne, Australia Author O'Hara, Timothy D. Department of Oceanography, University of Hawai'i at Manoa, Honolulu, USA Author Rabone, Muriel https://orcid.org/0000-0002-8351-2313 National Oceanography Centre, Southampton, UK Author Simon-Lledo, Erik UMR ISYEB, Department Origines et Evolution, Museum national d'Histoire Naturelle, Paris, France Author Smith, Craig R. https://orcid.org/0000-0002-3976-0889 School of Life Sciences, University of Hawai'i at Manoa, Honolulu, USA Author Watling, Les https://orcid.org/0000-0002-6901-1168 School of Life Sciences, University of Hawai'i at Manoa, Honolulu, USA Author Wiklund, Helena https://orcid.org/0000-0002-8252-3504 Department of Marine Sciences, University of Gothenburg, Gothenburg, Sweden Author Glover, Adrian G. https://orcid.org/0000-0002-9489-074X National Oceanography Centre, Southampton, UK text ZooKeys 2022 2022-07-18 1113 1 110 http://dx.doi.org/10.3897/zookeys.1113.82172 journal article http://dx.doi.org/10.3897/zookeys.1113.82172 1313-2970-1113-1 EB46BF265F2E51B3A83799886C5F084A Synallactes stet. CCZ_153 Fig. 39 Material. Clarion-Clipperton Zone • 1 specimen ; APEI 4; 6.9704°N , 149.9426°W ; 5009 m deep; 06 Jun. 2018 ; Smith & Durden leg.; GenBank : ON400714 (COI); NHMUK 2022.69; Voucher code: CCZ_153 . Description. Single specimen (Fig. 39A ). Body cylindrical, white, ~ 4 x as long as wide (L = 10 cm, W = 2.7 cm), flattened proximally and rounded distally; flattened ventral surface. Two rows, upper and lower, of lateral, small, conical, thin processes, similar to those around the proximal edge (Fig. 39D ). There is a row of yellowish, very small, tube feet in the mid-ventral surface, along the odd ambulacrum (Fig. 39E ). Skin firm but translucent. Colour on live and preserved specimen is white. Ossicles abundant on dorsal body wall, spatulated crosses only with a long spinous apophysis, end of arms spatulated with holes (Fig. 39B ). Ventral ossicles also spatulated crosses with a long spinous apophysis, smaller, sometimes with more than four arms, also spatulated ends of arms with holes (Fig. 39C ). Figure 39. Synallactes stet. CCZ_153 A in situ image B ossicles from dorsal skin C ossicles from ventral skin D dorsal view of specimen before preservation, E ventral view. Scale bars: 2 cm ( A ); 50 μm ( B, C ); 5 mm ( D, E ). Image attribution: Durden and Smith ( A ); Bribiesca-Contreras ( B, C ); Wiklund, Durden, Drennan, and McQuaid ( D, E ). Remarks. The closest matches for the barcoding gene COI sequence are published sequences from the genus Bathyplotes (89.9% similarity), also within the family Synallactidae . The sequence is distinct from the only sequence of Synallactes sp. (GenBank accession number: KX874365.1) included in the phylogeny (Fig. 34 ), and they were not recovered as a monophyletic group. The DeepCCZ specimen was recovered sister to species of Bathyplotes , with Synallactes sp. recovered separately from the other genera in the family Synallactidae , concordant with previous results ( Miller et al. 2017 ). Despite this, the specimen was assigned to the genus Synallactes based on external morphological characters that are concordant with those described from the genus. Species of Synallactes have previously been reported in the CCZ: Synallactes profundus (Koehler & Vaney, 1905) and Synallactes aenigma Ludwig, 1894; the latter being associated with manganese substrates. External morphology does not resemble to S. profundus . Ecology. This specimen was found on the sedimented seafloor of an abyssal plain on APEI 4 at 5008 m depth. Comparison with image-based catalogue. A very similar Synallactidae morphotype (i.e., Synallactes sp. indet., HOL_007) has been commonly encountered in seabed image surveys conducted across nodule field areas of the eastern CCZ (e.g., Amon et al. 2017b ), but not in abyssal areas of the Kiribati EEZ, where synallactid specimens were very rarely encountered. Family Deimatidae Theel , 1882