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 Freyastera cf. tuberculata (Sladen, 1889) Fig. 25 Material. Clarion-Clipperton Zone • 1 specimen ; APEI 4; 6.9879°N , 149.9123°W ; 5000 m deep; 02 Jun. 2018 ; Smith & Durden leg.; GenBank : ON400716 (COI); NHMUK 2022.80; Voucher code: CCZ_157 • 1 specimen ; APEI 4; 6.9873°N , 149.9331°W ; 5000 m deep; 06 Jun. 2018 ; Smith & Durden leg.; GenBank : ON400704 (COI); NHMUK 2022.79; Voucher code: CCZ_087 . Comparative material. Pacific Ocean • 1 specimen , holotype of Freyella benthophila Sladen, 1889; mid-South Pacific; 39.6833°S , 131.3833°W ; 4663 m deep; Challenger Expedition, Stn. 289; NHMUK 1890.5.7.1078. Atlantic Ocean • 1 specimen , syntype of Freyella tuberculata Sladen, 1889; between west coast of Africa and Ascencion Islands ; 22.3°N , 22.0333°W ; 4389 m deep; Challenger Expedition, Stn. 346; NHMUK 1890.5.7.1077. • 1 specimen , syntype of Freyella tuberculata ; between Canary Islands and Cape Verde Islands ; 2.7° S , 14.6833°W ; 4298 m deep; Challenger Expedition , Stn. 89; NHMUK 1890.5.7.1076 . Description. Two specimens (R = 106 mm, r = 3 mm; R = 164 mm, r = 6 mm); live specimens whitish on both actinal and abactinal surfaces, tube feet transparent with bright orange flattened discs (Fig. 25A, B ). Disc is small, somewhat rounded, slightly orange on actinal and abactinal surfaces (Fig. 25E, F ); with six long, slender arms (Fig. 25A-C ); lacking furrow spines (Fig. 25D ). Each abactinal plate on the genital area bears a single spinelet (Fig. 25E ), covered with a membrane with pedicellariae. Each mouth plate has two oral spines covered by a clear membrane bearing pedicellariae (Fig. 25F ); one located on the adoral margin of the mouth plate and the suboral spine located above the centre of the mouth plate. Figure 25. Freyastera cf. tuberculata (Sladen, 1889). Specimen CCZ_175: A in situ image C whole specimen D ventral surface of the arms before preservation. Specimen CCZ_087: B in situ image E details of dorsal disc F ventral disc surface before preservation. Scale bars: 2 cm ( A, B ); 1 cm ( C ); 2 mm ( D ); 1 mm ( E ); 0.5 mm ( F ). Image attribution: Durden and Smith ( A, B ); Wiklund, Durden, Drennan, and McQuaid ( C-F ). Remarks. The COI sequences were very similar to sequences of Freyastera cf. benthophila (Sladen, 1889) collected in the UK-1 contract area from the CCZ ( Glover et al. 2016a ), and which were recovered in a single clade (Fig. 24 ). Only arm segments were recovered from the UK-1 specimens, and although they were found to resemble F. benthophila , the whole specimens collected in the western CCZ differ from the original description for the species. Only five species are known for having six rays: F. sexradiata (Perrier, 1885), F. benthophila , F. tuberculata (Sladen, 1889), F. basketa Zhang et al., 2019 , and F. delicata Zhang et al., 2019 . However, F. benthophila is easily distinguished from the other two species by its abactinal armament; each abactinal plate bearing two or three spinelets covered with a simple membrane with no pedicellariae ( Sladen 1889 ). The specimens from the CCZ have abactinal spinelets covered by a membrane that bears pedicellariae (Fig. 25E ). They also differ from F. benthophila in having the spines on the adoral margin of the mouth-plates covered by a clear membrane bearing pedicellariae instead of an opaque membrane with no pedicellariae ( Downey 1986 ). In addition, the suboral spines are located above the centre of the mouth plate (Fig. 25F ), as in F. tuberculata , and not below the centre of the mouth plate as described for F. benthophila ( Downey 1986 ). Syntypes from F. tuberculata are from the Atlantic Ocean ( Sladen 1889 ), but it has been reported for the Eastern Tropical Pacific ( 0.05°N , 117.25°W ) at 4243 m depth ( Downey 1986 ). Unfortunately, there are no genetic sequences available for this species, but COI sequences from CCZ specimens are highly divergent from the sequence of F. benthophila collected in the Mariana Trench (K2P distance: 13-14%). In the phylogenetic tree they are also recovered in different clades, very close to another species reported herein, and to F. delicata and Freyastera sp. Yap (in Zhang et al. 2019 ) (Fig. 24 ). The specimen collected here represents the same species as found in the eastern CCZ, Freyastera cf. benthophila ( Glover et al. 2016b ). Ecology. One specimen was observed on the sedimented seafloor (CCZ_157), while another was sitting on a nodule with the actinal surface against the muddy seafloor and lifting the tip of the arms like a basket (CCZ_087). Both seastars were collected on abyssal sediments of APEI 4 at 5000 m depth. During morphological examination of these samples, the exoskeleton of a large (> 6 mm long), digested copepod was found in the stomach of specimen CCZ_157.