Genetic differentiation and species status within the snail leech Glossiphonia complanata aggregate (Hirudinea : Glossiphoniidae) revealed by RAPD analysis

Randomly amplified polymorphic DNA (RAPD) markers were employed to analyse genetic differentiation and taxonomic structure within the snail leech Glos siphonia complanata species aggregate. Three morphological types of snail l eeches, whose taxonomic validity was formerly mainly distrusted, occur thro ughout Europe. Six individuals of each morphotype from four locations in Sl ovenia were investigated. At two locations all three morphotypes occurred s yntopically, enabling the determination of reproductive isolation. PCR ampl ification with eleven decamer random primers yielded 177 reproducible marke r fragments, only one of which was monomorphic in all specimens. Genetic si milarity within morphotypes was substantially higher than within samples fr om the same locality but consisting of different morphotypes. The estimated nucleotide diversity within morphotypes (0.7-2.1 %) was tower than the nuc leotide divergence between them (5.1-8.3 %). UPGMA clustering and principal coordinate analysis revealed three groups concordant with the identified m orphotypes. They were tentatively assigned to the taxa Glossiphonia complan ata (LINNAEUS), G. concolor (APATHY) and G. nebulosa KALBE. Reproductive is olation between them is suggested by the presence of RAPD fragments specifi c to each taxon, and by the absence of common fragments in syntopic populat ions of the three taxa. This is strong support for the hypothesis that exte rnally very similar and anatomically nearly identical glossiphoniids belong to different biological species.