The Late Pleistocene mollusk fauna of Selitrennoye (Astrakhan province, Russia): A natural baseline for endemic Caspian Sea faunas Author van de Velde, Sabrina Naturalis Biodiversity Center, P. O. Box 9517, 2300 RA Leiden, the Netherlands sabrina.vandevelde@naturalis.nl Author Yanina, Tamara A. Moscow State University, Faculty of Geography, Leninskie Gory, 1, 119991 Moscow, Russia Author Neubauer, Thomas A. Naturalis Biodiversity Center, P. O. Box 9517, 2300 RA Leiden, the Netherlands & Department of Animal Ecology and Systematics, Justus Liebig University, Heinrich-Buff-Ring 26 - 32 IFZ, 35392 Giessen, Germany Author Wesselingh, Frank P. Naturalis Biodiversity Center, P. O. Box 9517, 2300 RA Leiden, the Netherlands text Journal of Great Lakes Research 2020 2020-10-31 46 5 1227 1239 http://dx.doi.org/10.1016/j.jglr.2019.04.001 journal article 5982 10.1016/j.jglr.2019.04.001 6d7090a8-a7b0-40b5-81f6-8d8e6fdc55f7 5019200 Dreissena elata Andrusov, 1897 ( Fig. 7 : 2, Fig. 8 : 4–5). *1897 Dreissensia [sic] polymorpha var. elata Andrusov : 353 , pl. 20, fig. 25. 2013 Dreissena elata ( Andrusov, 1897 ) – Bogutskaya et al.: 321 , fig. 108. Dimensions – max. L 9 mm , H 19.4 mm . Logvinenko and Starobogatov (1969) reported Hup to 30 mm . Characterization – Medium- to thick-shelled triangular-shaped Dreissena with a wide range of morphologies, ranging from an elongated form ( Fig. 8 : 4) to a short form ( Fig. 8 : 5). In general, the valves have a well-developed keel that runs close to the posteroventral margin; the latter is straight or can be concave in its upper half. The initial part of the dorsal margin is flaring and the inflection towards the lower dorsal margin is usually well developed. Adult shells can be somewhat flaring. The overall shell is broad and the lower margin is rounded. Taxonomic notes – The systematics and taxonomy of this species are not resolved. Dreissena elata has several characteristics in common with the widespread Eurasian D. polymorpha Pallas, 1771 (whose distribution nowadays also includes North America). The Caspian material resembles D. polymorpha , especially with regard to shape of the keel, but it is broader, thicker and somewhat flatter. However, also very slender forms exist together with intermediates in the studied material ( Fig. 7 : 2). Molecular studies would be required to assess whether D. elata and D. polymorpha are conspecific. Ecology – Before the introduction of Mytilaster minimus , D. elata was abundant in the South and Middle Caspian basins at depths of up to 35 m mainly on firm ground and shelly/stony substrate. By now, it is probably extinct ( Logvinenko and Starobogatov, 1969 ). The species occurred in salinities between 2 and 8 psu ( Bogutskaya et al., 2013 ).