Graecina, Cosel, 2006

Cosel, Rudo von, 2006, Taxonomy of tropical West African bivalves. VI. Remarks on Lucinidae (Mollusca, Bivalvia), with description of six new genera and eight new species, Zoosystema 28 (4), pp. 805-851 : 824

Genus Graecina n. gen.

TYPE AND ONLY SPECIES. — Graecina karinae n. sp.

DISTRIBUTION. — Northern Angola (Ambrizete), tropical West Africa.

DIAGNOSIS. — Shells medium-sized, subcircular, slightly longer than high, rather compressed. Beaks in front of the vertical midline. Surface with thin commarginal lamellae or cords only on the earlier part of the valves, becoming obsolete and then absent ventrally. Rest of the valves with growth lines and some coarser “growth stages”. Anterior area with two shallow radial depressions, anterior angle indistinct. Postero-dorsal area indistinct and not separated by a visible posterior angle. Lunule long, narrow, slightly asymmetrical, sunken. Escutcheon long, narrow and sunken, delimited by a sharp and prominent, narrowly laminate keel, but no long lamellate prolongations. Hinge arched, in the right valve with one well developed cardinal tooth and sometimes the vestiges of a posterior cardinal, and anterior and posterior laterals. Left valve with two cardinals and well marked anterior and posterior laterals. Anterior adductor scar rather elongate, with moderately long diverging part, pallial line meeting the scar in about its middle or just above it. Posterior adductor scar small. Inner margins smooth.

ETYMOLOGY. — The name goes back to Roman history as already does the name of the type genus of Lucinidae , Lucina ( Lucina is the Roman goddess of childbirth). Lucina is believed to have been the baptismal name of Pomponia Graecina , a noble Roman lady and wife of the conqueror of Britain, Aulus Plautius. The new genus Graecina n. gen. honours the same person as the genus Lucina .

REMARKS

This genus has an overall appearance of a large Myrtea ; especially with its raised and sharp escutcheonal keel, however, the valves are much more compressed, and the anterior adductor scars are more elongate, with a longer diverging part. In shell form and outline and with the small posterior adductor scar, this genus looks most similar to a new genus under description by Cosel & Bouchet (unpubl. data), however, Graecina n. gen. is much larger, has well defined cardinal and lateral teeth and commarginal lamellae on the earlier part of the valves; the pallial line meets the anterior adductor scar at a higher point and thus leaves a longer ventral diverging part. Another genus, especially similar in size and form of the anterior adductor is also under description by Cosel & Bouchet (unpubl. data). In that genus, the hinge is toothless, the hinge line is less bent and the lunule is shorter.