Notocina, Taylor, John D. & Glover, Emily A., 2019

Taylor, John D. & Glover, Emily A., 2019, Unloved, paraphyletic or misplaced: new genera and species of small to minute lucinid bivalves and their relationships (Bivalvia, Lucinidae), ZooKeys 899, pp. 109-140 : 109

Notocina gen. nov.

Type species.

Epicodakia falklandica Dell, 1964. Here designated.

Diagnosis.

Small (L to 3 mm), sub-ovoid, slightly longer than high. Umbones prominent. Posterior dorsal margin straight. Sculpture of low, rounded, commarginal lamellae with poorly defined fine radial ribs to anterior and posterior. Microsculpture densely punctate. Ligament short, protrudes above dorsal margin. Lunule broadly lanceolate. Hinge line narrow, left valve with two small cardinal teeth and anterior and posterior lateral teeth. Right valve with single, slightly bifid cardinal tooth and anterior and posterior lateral teeth. Anterior adductor muscle scar short, slightly detached from pallial line, inner shell margin finely denticulate.

Etymology.

notos in Greek meaning south, - cina as an abbreviation of Lucina. In reference to the southern Atlantic distribution. Female gender.

Remarks.

Dell (1964) placed N. falklandica in Epicodakia (type species E. consettiana Iredale, 1930) because of some similarity of hinge teeth and sculpture. He remarked that only two species of Epicodakia were known ( E. consettiana Iredale, 1930 and E. neozelanica Powell, 1937) but since then a number of other species from the Indo-West Pacific, Western Atlantic and Eastern Pacific have been classified in the genus ( Glover and Taylor 2007; 2016; Taylor et al. 2016; MolluscaBase). Molecular analyses place Epicodakia in the subfamily Codakiinae, close to Ctena species ( Taylor et al. 2016). Inclusion of ' Epicodakia ' falklandica indicates it belongs in the subfamily Lucininae in a well-supported position as a sister species to Troendleina suluensis Glover & Taylor, 2106 from 150-600 m in the Sulu Sea. Troendleina includes three described species, all from deeper water; T. marquesana Cosel & Bouchet, 2008 from the Marquesas Islands, T. musculator Cosel & Bouchet, 2008 from the Solomon Islands and T. suluensis Glover & Taylor, 2016 from the Philippines and we are aware of further undescribed species. There is no close similarity of Troendleina to E. falklandica in shell characters: species of the former are larger with lengths of 30-40 mm, a sculpture of growth increments with fine radial threads, small cardinal teeth, obscure or absent lateral teeth, and a finely dentate inner shell margin. Notocina falklandica has some similarity to Parvilucina species in size and shell characters but is not closely aligned in molecular trees. Another unusual small species Guyanella clenchi from the southern Caribbean ( Taylor et al. 2016) is similar to Notocina falklandica in size but differs in having a distinctive internal ligament and lacks any radial sculpture. Neither Troendleina , Parvilucina nor Guyanella species possess the punctate microsculpture that occurs in N. falklandica and sporadically amongst other Lucinidae including species of Myrteinae, some Ctena , Epicodakia and Codakia species ( Codakiinae) and Funafutia levukana ( Lucininae) ( Glover and Taylor 2016).