Juliacorbula, Olsson & Harbinson, 1953

Arruda, Eliane P., 2020, Taxonomic revision of the recent marine Corbulidae (Mollusca, Bivalvia) from Brazil, Zootaxa 4851 (1), pp. 1-59 : 36

Genus JULIACORBULA Olsson & Harbinson, 1953

Juliacorbula Olsson & Harbinson, 1953 : type species Corbula cubaniana d’Orbigny, 1853 (in 1841–1853) (original designation), Recent Western Atlantic .

Diagnosis. Adult shell of moderate in size, heavy, subtrigonal to subtrapezoidal, nearly equivalve, equilateral to subequilateral, with strong, sharp keel between central and posterior slope and long and truncated posterior margin; weakly rostrate posterior slope. Right valve with marginal groove along the free internal border where the opposite valve fits in. Sculpture of moderate to strong commarginal ribs, similar in both valves. Lunular area recessed. Escutcheon well defined by ribs on both valves, more conspicuous on the right.

Right valve hinge with anterior cardinal tooth, curved upwards at the dorsal margin, and with posterior deep resilial socket. Left valve hinge with anterior cardinal socket, and with posterior chondrophore; moderately broad and projected chondrophore with one well developed ridge on the dorsal side and a tooth-like knob on its posterior margin. Nepioconch not distinguished.

Remarks. Juliacorbula differs from Caryocorbula by its subtrigonal to subtrapezoidal outline with a strong and sharp keel between the central and posterior slope and the conspicuously truncated posterior margin; Caryocorbula species have more trigonal shells. Olsson & Harbinson (1953) emphasized the presence of two ridges in the chondrophore of Juliacorbula , distinguishing it from Caryocorbula . I understand that Olsson & Harbinson (1953) referred to the radial ridge that divides the chondrophore into an anterior and a posterior area, and the tooth-like knob on the posterior margin of chondrophore (see diagnosis).

According Goodwin et al. (2008) Juliacorbula scutata Gardner, 1943 has GF1 growth pattern. The great similarity between specimens in pre-accretion and post-accretion stages indicates that the growth pattern in Juliacorbula is GF1, in agreement with Goodwin et al. (2008).