One Beringian Genus Less: A Re-Assesment Ofpacifimyxaskruglov & Starobogatov, 1985 (Mollusca: Gastropoda: Lymnaeidae) Questions The Current Estimates Of Beringian Biodiversity

The taxonomic position of three nominal species of lymnaeid snails placed by Kruglov & Starobogatov (1993) into the subgenusLymnaea(Pacifimyxas) Kruglov & Starobogatov, 1985, has been re-assessed based on a molecular genetic study of topotypic specimens and an examination of the type series and other materials available. It has been shown that the two species,Lymnaea(Pacifimyxas)magadanensisKruglov & Starobogatov, 1985 andLymnaea(Pacifimyxas)streletzkajaeKruglov & Starobogatov, 1985, are identical with the speciesKamtschaticana kamtschatica(Middendorff, 1850) and must be treated as its junior synonyms. Hence,Pacifimyxasbecomes a junior synonym ofKamtschaticanaKruglov & Starobogatov, 1984. The taxonomic identity of the third species ofPacifimyxas,Lymnaea(Pacifimyxas)perpolita, remains obscure, and this species is considered here astaxon inquirendum. Two other nominal species,Lymnaea aberrans(Westerlund, 1897) andLymnaea middendorffi(W. Dybowski, 1904), have been synonymized withK. kamtschaticabased on morphological and geographical evidence. The lectotype ofLimnaea peregravar. middendorffiis designated. The actual level of species richness in the Beringian freshwater malacofauna may be 20-25% lower than it was determined on the basis of the traditional system. Some implications of this outcome for the biogeography of the Beringian freshwater fauna are discussed.