Accepted by J. Gerber: 23 Mar. 2011; published: 13 Apr. 2011 55 ZOOTAXA ISSN 1175-5326 (print edition) ISSN 1175-5334 (online edition) Copyright © 2011 · Magnolia Press Zootaxa 2817: 55–58 (2011) www.mapress.com/ zootaxa/ Correspondence A new species of stagnicoline snails (Mollusca: Gastropoda: Lymnaeidae) from the extreme North of Western Siberia MAXIM V. VINARSKI Museum of Siberian Aquatic Molluscs, Omsk State Pedagogical University, 14 Tukhachevskogo Emb., Omsk, Russian Federation, 644099. E-mail: radix.vinarski@gmail.com The data on taxonomy and distribution of stagnicoline snails 1 of the northern part of Western Siberia (Lower Ob’ drainage basin) are relatively scant. The most recent survey of this group in the region was presented by Dolgin (2001) in his unpublished thesis where three stagnicoline species are recorded: Lymnaea (Stagnicola) palustris (O.F. Müller, 1774), L. (S.) terebra (Westerlund, 1885), and L. (S.) zebrella (B. Dybowski, 1913). Earlier authors published some data on stagnicolines of the northern water bodies of Western Siberia (Westerlund 1887; Lindholm 1919; Khokhutkin 1966; Drozdov 1967; Dolgin & Johansen 1980; Dolgin & Novikova 1984), however, all those researchers, as well as Dolgin (2001), did not study the anatomical traits of the snails they had at their disposition and, thus, species identification was carried out solely on the basis of conchological characters. Meanwhile, conchological traits in stagnicoline snails are known to display a large extent of intra- and interspecific variation (Jackiewicz 1993), and therefore are not completely suitable for reliable species determination. In order to discriminate between numerous lymnaeid species, the study of shell characters should be accompanied by the examination of the structure of the reproductive organs. In some cases, it is utterly impossible to distinguish between certain stagnicoline species on the ground of conchological traits (Jackiewicz 1993). Having examined a large series of stagnicoline snails collected in water bodies of the Yamal Peninsula and the Polar Urals, I discovered that as many as six species of this group inhabit this region (Fig. 1). The species could be distinguished from each other by both conchological and anatomical features summarized in the determination key (see below). The six stagnicoline species of the North part of Western Siberia are: L. (S.) palustris, L. (S.) terebra, L. (S.) zebrella, Lymnaea (S.) ventricosella (B. Dybowski, 1913), Lymnaea (S.) saridalensis Mozley, 1934 and Lymnaea (S.) gloeeri sp.n. The description of the latter species is given below. Snails were killed and fixed in 96 % ethanol in the field and later transferred to 70 % ethanol for permanent preservation. The material studied is kept in the collection of the Museum of Siberian Aquatic Molluscs (MSAM hereafter), Omsk State Pedagogical University, unless stated otherwise. Lymnaea (Stagnicola) gloeeri sp. nov. (Fig. 1, M–R, Table 1) Type locality. Russia, Tyumen Region, Ra-Iz Ridge (Polar Urals), small artificial pond lying at the base of the railway embankment at kilometer 141 of the Labytnangi–Seida railroad (approximate coordinates: 6650 N, 6540 E). Type material (all from the type locality). Holotype and 5 paratypes in the Zoological Institute of the Russian Academy of Sciences, Sankt-Petersburg (ZIN 1). 9 paratypes (MSAM 15-1493, 15-2048). Other material studied. 7 specimens from the type locality in Senckenberg Naturhistorische Sammlungen Dresden, Germany (SNSD 52882–52887). Shell description. Shell turriculate-conical, solid, light-brown, medium-sized (height up to 22.5 mm). Whorls number up to 7.0. Whorls strongly inflated, sometimes almost stepped, separated by deep, oblique suture. Spire conical, tangent line slightly convex. Body whorl moderately inflated, relatively high, its surface covered by growth lines and (in some shells) weakly malleated. Aperture ovate, columellar fold weakly developed. Columellar lip narrow, thin, completely covering the umbilicus. Protoconch usually corroded with 1.0–1.5 initial whorls being destroyed. 1. I use the term ‘stagnicoline snails,’ or ‘stagnicolines,’ for the designation of an informal and clearly polyphyletic group of lymnaeid species corresponding to the species Lymnaea palustris (O.F. Müller, 1774) sensu Hubendick (1951). It has a wide Holarctic distribution and includes at least two independent clades of Palaearctic and Nearctic origin, respectively (Bargues et al. 2006).