Didacna subcrassa Pravoslavlev, 1939

van de Velde, Sabrina, Yanina, Tamara A., Neubauer, Thomas A. & Wesselingh, Frank P., 2020, The Late Pleistocene mollusk fauna of Selitrennoye (Astrakhan province, Russia): A natural baseline for endemic Caspian Sea faunas, Journal of Great Lakes Research 46 (5), pp. 1227-1239 : 1234

Didacna subcrassa Pravoslavlev, 1939

( Fig. 5 : 1).

1983 Didacna subcrassa Pravoslavlev, 1939 – Popov: 199, pl, 8, figs. 11–16.

2007 Didacna subcrassa subcrassa Pravoslavlev, 1939 – Nevesskaja: 920, pl. 16, figs. 14–18.

Dimensions – max. L 32.5 mm, H 25.5 mm.

Characterization – Thin-shelled subtrapezoid to subovate to subtrigonate species, usually flat and trigonoid in juvenile stages. The posterodorsal keel is poorly delimited, the low angle posterior bend is rounded. The posterior ridge is subrounded. It is more pronounced in juvenile stages and fading in adult stages. The species has 19–26 posterior ribs. Interspaces are about half to equal width of the ribs. Anterior ribs are sometimes poorly developed and rib width increases towards the posterior keel. Beak is protruding, the hinge is thin. The location of the semidiameter in juveniles is on the posterior ridge but in adults becomes located towards the center of the shell.

Ecology – Unknown (extinct).

Figures

Fig. 5. Overview of the Cardiidae.(1) Didacna subcrassa; (a) RGM-1309816 LV;(b) RGM-1309815 RV.(2) Didacna subpyramidata; (a) RGM-1309797 LV; (b) RGM-1309814 RV. (3) Didacna subcatillus; (a) RMG-1309819 LV; (b) RMG-1309820 RV. (4) Didacna emendata; (a) RGM-1309799 LV; (b) RGM-1309798 RV. (5) Didacna ebersini; A (a) RGM- 1309817 LV; (b) RGM-1309818 RV. (6) Didacna cristata; (a) RGM.1309800 LV; (b) RGM.1309801 RV. Scale bars = 1 cm.