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 Holascus stet. CCZ_078 Fig. 59 Material. Clarion-Clipperton Zone • 1 specimen ; APEI 7; 5.0443°N , 141.8162°W ; 48745 m deep; 28 May. 2018 ; Smith & Durden leg.; GenBank : ON400700 (COI), ON406636 (18S), ON406613 (16S), ON406599 (28S), ON411256 (ALG11); NHMUK 2022.7; CCZ_078 . Description. Single specimen; lophophytous white sponge (Fig. 59A ). Band-like body, collar formed from thin wall with two large openings, with lower opening being larger than upper opening (Fig. 59B, C ). Body height of 4.8 cm, lower body diameter of 15.1 cm, and upper body diameter of 11.8 cm. basalia almost as long as the body height, protruding from the lower margin and anchoring it to the sediment (Fig. 59A ). Figure 59. Holascus stet. CCZ_078 A in situ image B lateral view of specimen before preservation C top view. Scale bars: 2 cm ( A ); 1 cm ( B ). Image attribution: Durden and Smith ( A ); Wiklund, Durden, Drennan, and McQuaid ( B, C ). Remarks. Morphological external characters are concordant with the description of Holascus spinosus Kersken, Janussen & Martinez Arbizu, 2019, which was described from the IOM area in the CCZ. The closest genetic matches on GenBank for the 16S correspond to species within the genus Holascus (2.1-3.5% genetic divergence), with the holotype of Holascus spinosus being the closest match (2.1% genetic divergence). There are no 18S sequences available for H. spinosus , but it is 0.23% divergent from another species within the genus, H. euonyx (Lendenfeld, 1915), from which it differs morphologically. In the phylogenetic tree it was recovered, with low support, as sister to H. spinosus (Fig. 54 ), but 16S genetic divergence suggested these to be separate species. Ecology. This specimen was found anchored to abyssal sediments of APEI 7 at 4874 m depth. Comparison with image-based catalogue. A very similar Holascus sp. morphotype (i.e., Holascus sp. indet., HEX_014) has been commonly encountered in seabed image surveys conducted across nodule fields areas of the eastern CCZ and in abyssal areas of the Kiribati EEZ. Subfamily Bolosominae Tabachnick, 2002 Bolosominae stet. CCZ_198 Fig. 60 Material. Clarion-Clipperton Zone • 1 specimen; APEI 1; 11.2518°N , 153.6053°W ; 5205 m deep; 10 Jun. 2018; Smith & Durden leg.; GenBank: ON400728 (COI), ON406637 (18S), ON406614 (16S), ON406600 (28S); NHMUK 2022.10; Voucher code: CCZ_198. Description. Single specimen; lophophytous white sponge (Fig. 60A, B ). Body is cup- to bell-shaped, slightly wider than long (L = 10 cm, W = 11 cm), with a long, slender stalk (L = 70 cm) anchored to soft sediment. Central osculum with thick body walls. Figure 60. Bolosominae stet. CCZ_198 A, C in situ images B specimen before preservation. Scale bars: 5 cm ( A, C ). Image attribution: Durden and Smith ( A, C ); Wiklund, Durden, Drennan, and McQuaid ( B ). Remarks. The closest match with the 18S sequence is the holotype of Hyalostylus microfloricomus Kersken, Janussen & Martinez Arbizu, 2019 (99.8%), described from the Heip Mountains in the GSR contract area in the CCZ at 3788 m depth ( Kersken et al. 2019 ). However, in the phylogenetic tree (Fig. 54 ) it was recovered in a well-supported clade representing the subfamily Bolosominae , but subclades were not well supported and hence the specimen is not attributed to any genera. Ecology. This specimen was collected on abyssal sediments of APEI 1 at 5205 m depth, and was anchored to the sediment. Comparison with image-based catalogue. A very similar stalked sponge morphotype (i.e., Hexactinellidae ord. indet., HEX_026) has been encountered in seabed image surveys conducted at the eastern CCZ, but not in abyssal areas of Kiribati's EEZ. In seabed images, HEX_026 highly resembles Hyalonema (Cyliconemaoida) campanula Lendenfeld, 1915, as identified by Kersken et al. (2019) based on morphological traits observed in specimens encountered in the eastern CCZ. Order Sceptrulophora Mehl, 1992 Family Euretidae Zittel, 1877 Subfamily Chonelasmatinae Schrammen, 1912