TAXONOMICAL NOTES ON EURO-SIBERIAN FRESHWATER MOLLUSCS: 2. REDESCRIPTION OF PLANORBIS (GYRAULUS) STROEМI WESTERLUND, 1881 (MOLLUSCA: GASTROPODA: PLANORBIDAE)

摘要

Gyraulus stroemi Westerlund, 1881 is a species distinct from G. acronicus (A. Férussac, 1807). It was, how_ever, overlooked by the W-European malacologists for a long time. In this paper the shells as well as the anatomy have been studied thoroughly (including syntypes of Planorbis stroemi) and compared with morphological and anatomical features of G. acronicus. By means of scanning of museum collections and the literature, a distribution map was constructed which reveals that G. stroemi is a species that lives predominantly in the Artic and Subarctic.