Phylogenetic relationships in European erpobdellid leeches (Hirudinea: Erpobdellidae) inferred from restriction-site data of the 18S ribosomal gene and ITS2 region

Abstract

The PCR-amplified 185 rRNA gene and ITS2 region were used for a restriction-site analysis to infer phylogenetic relationships among European representatives of the leech family Erpobdellidae and to test the phylogenetic reliability of the morphological characters used in this family till now. Fragment patterns produced by 11 restriction endonucleases in the 18S rRNA gene and by nine in the ITS2 region showed a higher interspecific variation in the latter than in the former genome component. No intraspecific variation could be detected, even among geographically very distant populations, except for the two supposed subspecies Trocheta b. bykowskii and T. b. krasense. The estimated overall nucleotide divergence (d) was lower in the genus Erpobdella (d = 0.015–0.061) than in the genera Dina and Trocheta (d = 0.049–0.090). E. testacea and E. monostriata do not seem to be as closely related to each other as previously thought; their pairwise nucleotide divergence (0.061) is highest within the genus Erpobdella. The nucleotide divergence between T. b. bykowskii and T. b. krasense (0.090), which greatly resemble each other morphologically, was surprisingly high. Phylogenetic trees were inferred via neighbour-joining and maximum parsimony methods. The trees support the monophyly of Erpobdellidae and the subdivision into two groups according to the pattern of annulation (the Erpobdella clade and the Dina-Trocheta clade). Further subdivision based on annulation patterns and other morphological characters is not supported. There was no molecular evidence for the monophyly of the genus Dina and the monophyly of the genus Trocheta.