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 6A0BCD992749450C874B440D0C0A232C Thyasira sp. (NHM_180) Material examined. NHM_051 NHMUK 20170038, collected 2013-10-09, 13.8372 -116.55843, 4336 m. http://data.nhm.ac.uk/object/49b2f599-bda4-4177-932f-59effe8a3320 NHM_180 NHMUK 20170039, collected 2013-10-13, 13.93482 -116.55018, 4082 m. http://data.nhm.ac.uk/object/b84e470d-73bc-413b-88f9-3d702509a37a Description. Minute, thin-shelled, translucent, anteriorly extended, longer than high, umbones posterior of mid-line, posteriorly angulate, antero-dorsal margin long, evenly curved, shell surface smooth. Gill with single demibranch of about 10 widely spaced filaments, ventral edge of the gill does not cover the body pouches. Foot relatively large with distal bulb (Fig. 3). NHM_180 length 1.1 mm. Figure 3. Thyasira sp. (NHM_180) A Preserved specimen (NHM_180) with pieces of polymetallic nodule adhered to shell margin B Additional small specimen (live imaged at sea) NHM_051. Scale bar: 0.5 mm (A). Image attribution Glover, Dahlgren and Wiklund, 2017. Genetic data. GenBank NHM_051 18S-MF157468, COI-MF157501; NHM_180 18S-MF157478. Remarks. Forms a monophyletic clade with four other thyasirid species (Fig. 5) and distinct from all other AB01 specimens. No genetic matches on GenBank. Morphologically the species is similar in shape to abyssal thyasirid species ( Thyasira inflata , T. transversa ) from the south Atlantic described and placed in Thyasira (Mendicula) by Payne & Allen (1991) but not similar to the type species of Mendicula (Lucina) induta Hedley, 1907 = M. memorata Iredale, 1924) or the widespread Mendicula ferruginosa (Forbes, 1844). No similarly shaped species has been recorded from the abyssal eastern Pacific. Ecology. Found in polymetallic nodule province.