Adacna laeviuscula ( Eichwald, 1829 )

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 : 1230-1231

Adacna laeviuscula ( Eichwald, 1829)

( Fig. 4 : 1).

1986 Adacna (Adacna) laeviuscula (Eichwald, 1831) . – Yakhimovich et al.: 85, pl. 11, fig. 8.

2013 Adacna laeviuscula ( Eichwald, 1829) . – Bogutskaya et al.: 377, fig. 154, photo 48.

Dimensions – max. L 32 mm, H 21 mm.

Characterization – Large, subquadrate to subtrigonal thinshelled flat cardiid with strong posterior and slight anterior gape; dorsal margins relatively straight; relatively few ribs that are thin in juvenile stages and become very flat and separated by barely perceptible grooves in adult stages; hinge is a mostly edentulous, straight and flat ridge; in juvenile specimens a small cardinal tooth may be present that disappears in adult stages.

Ecology – This species has been listed from the entire CS from water depths between 35 and 100 m in salinities of at least 4 psu ( Bogutskaya et al., 2013; Logvinenko and Starobogatov, 1969). The common occurrence of fresh, paired specimens on exposed beaches of the middle Caspian (Turali, Russia; Sirvan, Azerbaijan: pers. observ. FW) demonstrates that A. laeviuscula has viable populations in foreshore settings above storm wave base indicating shallower habitats than previously reported.

Figures

Fig. 4. Cardiidae. (1) Adacna laeviuscula; (a) RGM.1309812 LV; (b) RGM.1309813 RV. (2) Adacna minima; (A) RGM.1309811 LV; (b) RGM.1309810 RV. (3) Monodacna semipellucida, RGM.1309802 RV; (4) Monodacna caspia s.l. (a) RGM.1309803 LV; (b) RGM.1309804 RV. (5) Hypanis plicata; (a) RGM.1309808 LV (b) RGM.1309809 RV. Scale bars = 1 cm.