65 Malak. Abh. 24 Does Gyraulus rossmaessleri (Gastropoda: Planorbidae) inhabit Siberia? MAXIM V. VINARSKI, ALFRIED V. KARIMOV & SVETLANA I. ANDREEVA Museum of Siberian Water Molluscs, Omsk State Pedagogical University, Tukhachevskogo Emb. 14. 644099. Omsk, Russian Federation; radix@omskcity.com Abstract. The paper deals with new findings of the species Gyraulus (Lamorbis) rossmaessleri (Auerswald in A. Schmidt, 1852) in waterbodies of Siberia. It was commonly accepted earlier that this species has an entirely European distribution, however, the newly obtained data show that the range of the species covers almost all the territory of Siberia as well. The taxonomic position of two related species: Planorbis planoconcavus Westerlund, 1897, described from the Altay Region, and Anisus starobogatovi Frolova, 1984 from the Northern Kazakhstan is discussed. A new synonymy is established: Planorbis rossmaessleri Auerswald in Schmidt = Planorbis planoconcavus Westerlund, syn. n. The assumption that Anisus starobogatovi is a junior synonym of P. rossmaessleri is offered, though because of the absence of the type series of the former species, it is not possible to establish such a synonymy definitely. Kurzfassung. Kommt Gyraulus rossmaessleri (Gastropoda: Planorbidae) in Sibirien vor? – Die Arbeit befasst sich mit Neunachweisen von Gyraulus (Lamorbis) rossmaessleri (Auerswald in A. Schmidt, 1852) aus Gewässern Sibiriens. Es war bisher allgemein anerkannt, dass diese Art ausschließlich eine europäische Verbreitung besitzt. Neue Daten haben uns allerdings gezeigt, dass das Verbreitungsgebiet ebenso Sibirien umfasst. Der taxonomische Status zweier nahestehender Arten: Planorbis planoconcavus Westerlund, 1897, beschrieben aus der Altay Region und Anisus starobogatovi Frolova, 1984 aus dem Norden Kasachstans, wird diskutiert. Eine neue Synonymie wird vorgestellt: Planorbis rossmaessleri Auerswald in Schmidt = Planorbis planoconcavus Westerlund, syn. n. Es wird die Annahme vertreten, dass Anisus starobogatovi ein jüngeres Synonym von P. rossmaessleri ist, obwohl die Typusserie der erstgenannten Art nicht auffindbar und es eigentlich nicht möglich ist, dieses Synonym eindeutig zu etablieren. . Gyraulus rossmaessleri (Gastropoda: Planorbidae) ? – Gyraulus (Lamorbis) rossmaessleri (Auerswald in A. Schmidt, 1852) . , , , . - Planorbis planoconcavus Westerlund, 1897, , Anisus starobogatovi Frolova, 1984 . : Planorbis rossmaessleri Auerswald in Schmidt = Planorbis planoconcavus Westerlund, syn. n. , Anisus starobogatovi Planorbis rossmaessleri, , A. starobogatovi , . Key words. Planorbidae, Gyraulus rossmaessleri, geographic distribution, Siberia. Introduction The generic position of a snail species, described originally as Planorbis rossmaessleri Auerswald (in A. Schmidt, 1852), is still disputable. Western European malacologists unanimously place this species into the genus Gyraulus Agassiz in Charpentier, 1837 (PIECHOCKI 1979; MEIER- BROOK 1964, 1983; GLÖER 2002), whereas their Russian and Ukrainian colleagues consider it to be a member of the genus Choanomphalus Gerstfeldt, 1859, most representatives of which inhabit the Baikal Lake (STAROBOGATOV 1967; STADNICHENKO 1990; STAROBOGATOV et al., 2004). Initially, STAROBOGATOV (1967) placed Ch. rossmaessleri into the subgenus Lamorbis Starobogatov, 1967, but recently PROZOROVA & STAROBOGATOV (1997) have established a separate subgenus Pseudogyraulus of the genus Choanomphalus with Ch. rossmaessleri as : 65–76 © Malakologische Abhandlungen, ISSN 0070-7260, Dresden 01.06.2006