Afrolucina Cosel 2006, n. gen.

Genus Afrolucina n. gen.

TYPE AND ONLY SPECIES. — Afrolucina discontinua n. sp.

ETYMOLOGY. — The name reflects that this genus was discovered on the African shelf.

DISTRIBUTION. — Tropical West Africa.

DIAGNOSIS. — Shells small, subcircular, slightly longer than high, rather compressed. Beaks slightly in front of the vertical midline. Surface with numerous fine and more or less densely spaced commarginal lamellae, umbonal area appearing smooth. Interspaces with very fine growth lines. Antero-dorsal angle very shallow, anterior area well marked. Postero-dorsal area separated by a rounded posterior angle. Lunule short, broad, markedly asymmetrical, in the right valve broad, in the left valve very narrow, sunken. Escutcheon long, narrow and sunken. Hinge line curved, hinge with one small, well defined cardinal tooth in the right valve and two in the left valve. Anterior and posterior lateral teeth in the right valve indistinct, in the left valve almost obsolete. Anterior adductor scar rather elongate, with diverging part about half its length or slightly shorter. Posterior adductor scar small. Inner margins smooth.

REMARKS

This genus is most similar to a group of deeper water lucinids from the Indo-Pacific discussed in detail by Cosel & Bouchet (unpubl. data), which comprises some new genera, however, none of them are really identical to Afrolucina n. gen. This Indo-Pacific group has superficial resemblance to Lucinoma, but that genus is characterized by the presence of well developed hinge teeth and a long and slender diverging part of the anterior adductor scar which meets the pallial line near the upper (dorsalward) end of the impression. The species of the group here discussed have a nearly edentulous hinge, whereas in the West African Afrolucina discontinua n. gen., n. sp., small cardinals are present. The spectacular lunular asymmetry indicates affinities of Afrolucina n. gen. to the Myrtea group and is not seen as this in the Indo-West Pacific genera. All genera, however, share a much shorter and broader diverging part of the anterior adductor scar, which is met by the pallial line in its middle, another character of the Myrtea group.

The genus Tinalucina n. gen. is distinguished by the more tumid valves, the more protruding um- bones, the more regular commarginal sculpture, the more equal-sized adductor scars with short and broad diverging part of the anterior one, the less asymmetrical lunule and the smaller shell size.