Karyotypes of european species of radix (Gastropoda: Pulmonata: Lymnaeidae) and their relevance to species distinction in the genus

Karyotypes of Radix auricularia (Linnaeus, 1758) and three disputable taxa considered by different authors as distinct species or assigned as forms of Radix peregra (Muller, 1774), sensu lato - R. labiata (Rossmassler, 1835), R. balthica (Linnaeus, 1758), and R. ampla (Hartmann, 1821) - were studied with preparations obtained from gonad tissues by the airdrying method. The studied taxa have the same diploid number (2n = 34), but are characterized by different morphology of some chromosome pairs. In particular, R. labiata (traditionally identified as R. peregra, s. s.) and R. balthica (= R. ovata in traditional understanding) differ in the number of subtelocentric chromosomes (1 and 5, respectively), species status of these taxa being also supported by pronounced differences in centomeric indexes of chromosome pairs 4 and 16. Species distinctness of R. ampla is supported by differences in three chromosome pairs, and karyological similarity between this taxon and R. balthica is also noted. FN values varied among the studied taxa from 56 in R. ampla to 66 in R. labiata. The known karyological characters are traced on phylogenetic trees suggested by recent molecular reconstructions. This study demonstrates that karyology can be an effective tool for aiding taxonomic distinctions of historically problematic groups of molluscs