Abyssal fauna of the UK- 1 polymetallic nodule exploration area, Clarion-Clipperton Zone, central Pacific Ocean: Mollusca Author Wiklund, Helena Author Taylor, John D. Author Dahlgren, Thomas G. Author Todt, Christiane Author Ikebe, Chiho Author Rabone, Muriel Author Glover, Adrian G. text ZooKeys 2017 707 1 46 http://dx.doi.org/10.3897/zookeys.707.13042 journal article http://dx.doi.org/10.3897/zookeys.707.13042 1313-2970-707-1 6A0BCD992749450C874B440D0C0A232C Bentharca cf. asperula (Dall, 1881) Material examined. NHM_108 NHMUK 20170061, collected 2013-10-11, 13.79335 -116.70308, 4081 m. http://data.nhm.ac.uk/object/9d29d7ec-55cd-4b41-929a-2379be221263 NHM_150 NHMUK 20170062.1-2, collected 2013-10-11, 13.75833 -116.69852, 4080 m. http://data.nhm.ac.uk/object/96bfe548-f511-49c4-b2a3-0a9a45f9154b NHM_170 NHMUK 20170063, collected 2013-10-11, 13.7936 -116.70308, 4078 m. http://data.nhm.ac.uk/object/8d9beefd-2fbc-4204-9bf8-90551419ac1c NHM_282 NHMUK 20170064, collected 2013-10-17, 13.75583 -116.48667, 4076 m. http://data.nhm.ac.uk/object/ccdd114d-c8a8-47da-ba84-8b8ca5125a6a NHM_427 NHMUK 20170065, collected 2013-10-20, 13.86367 -116.54432, 4050 m. http://data.nhm.ac.uk/object/1d462c2a-bb98-4369-afc3-63a7c33a4bdd NHM _454 NHMUK 20170066, collected 2013-10-21, 13.90165 -116.59, 4163 m. http://data.nhm.ac.uk/object/a30eab51-5f52-4fec-89d7-d47152895c92 Description. Shell elongate, trapezoidal, strongly inequilateral, anteriorly attentuated and posteriorly expanded, umbones small, low, dorsal edge straight. Byssal sinus in ventral margin. Sculpture of irregular commarginal lamellae and low radial ribs but covered by a thick, shaggy, brown periostracum with projecting scales. Two pre- and post- umbonal hinge teeth with each tooth crossed by transverse grooves giving a lobate appearance (Fig. 13E, F). Inner shell margin smooth. DNA voucher NHM_150 shell length 3.2 mm shell width 1.9 mm. Figure 13. Bentharca cf. asperula (Dall, 1881) A Voucher specimen NHM_150 live after recovery B Specimen NHM_150 after preservation and dissection for DNA sample showing valves C Specimen NHM_108 Live D-F Specimen NHM_150 SEM showing shell ornamentation and hinge teeth. Scale bars: 1 mm (A, E); 0.5 mm (B); 0.2 mm (F). Image attribution Glover, Taylor, Dahlgren & Wiklund, 2017. Genetic data. GenBank NHM_108 18S-MF157470, COI-MF157502; NHM_150 18S-MF157476; NHM_170 18S-MF157477; NHM_282 18S-MF157490, COI-MF157513; NHM_427 18S-MF157496; NHM_454 18S-MF157499. Remarks. Bentharca asperula has been regarded as a cosmopolitan deep-water species with a considerable recorded depth range of 430-5005 m ( Knudsen 1967 , 1970 , Coan and Valentich-Scott 2012 ) from Atlantic, Indian and Pacific Oceans. The lectotype and paralectotypes (USNM 63174, 887339, 94363) originated from the Gulf of Mexico, off Yucatan, 2868 m (Blake stn 33). Because of its epifaunal, byssate life habit B. asperula shows considerable shape variation and Knudsen (1967) synonymised several nominal species and described how the number of hinge teeth increases with shell size (age). Without supporting genetic evidence from samples from different oceans it is impossible to test whether the species is truly cosmopolitan. Perhaps significantly, no shell has been described with as few hinge teeth as the present sample and none with the transverse grooves (Fig. 13F). No genetic matches on GenBank. Ecology. Quite abundant. Found in polymetallic nodule province.