Thyasira sp. (NHM_180)

Wiklund, Helena, Taylor, John D., Dahlgren, Thomas G., Todt, Christiane, Ikebe, Chiho, Rabone, Muriel & Glover, Adrian G., 2017, Abyssal fauna of the UK- 1 polymetallic nodule exploration area, Clarion-Clipperton Zone, central Pacific Ocean: Mollusca, ZooKeys 707, pp. 1-46 : 3-4

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.

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.