Tucetona Iredale, 1931

Valentich-Scott, Paul & Garfinkle, Elizabeth A. R., 2011, A new species of Tucetona (Bivalvia: Glycymerididae) from Mexico, Zootaxa 2769, pp. 65-68 : 65

Genus Tucetona Iredale, 1931

Pectunculus Lamarck, 1799 , non da Costa, 1778. Type species (monotypy): Arca pectunculus Linnaeus, 1758 . Holocene, IndoPacific.

Tucetona Iredale, 1931 . Type species (original designation): Pectunculus flabellatus Tenison-Woods, 1878 . Holocene, southwestern Pacific.

Bellaxinaea Nicol & Jones, 1984 . Type species (original designation): Axinaea intercostata Gabb, 1860 . Eocene– Oligocene, southeastern U.S.

Description. Shell subcircular to subtrigonal; beaks orthogyrate, small to moderate in size, narrow to broad; sculpture of about 18–46 rounded to rectangular radial ribs, bifurcate in some species, commarginal striae weak to strong; interspaces narrow to moderately wide, shallow to moderately deep; posterior and anterior adductor scars and pallial line well impressed; hinge plate moderately curved, narrow to moderately wide; teeth straight to moderately curved; hinge plate of about 18–20 taxodont teeth; ligament with 3–5 chevron grooves.

This genus differs from Axinactis Mörch, 1861 , which has fewer, wider radial ribs with moderately wide interspaces, deep radial grooves on the ribs and interspaces, and a moderately broad beak. This genus differs from Glycymeris da Costa, 1778, which has low, rounded, smooth radial ribs that do not bifurcate, narrow interspaces, and a narrow beak. Species with a greater tendency for rib splitting, such as Tucetona bicolor Reeve, 1843 , have been segregated as subgenus Bellaxinaea .