Molecular re-assessment of some phylogenetic, taxonomic and biogeographic relationships between the leech genera Dina and Trocheta (Hirudinea: Erpobdellidae)

Abstract

The three most abundant and species-rich genera of erpobdellid leeches – Erpobdella, Dina and Trocheta – have traditionally been distinguished by their annulation pattern. Erpobdella has five unsubdivided annuli per somite, in Dina the last annulus is widened and subdivided once, and in Trocheta, the last and often also the first annulus is further subdivided. The last two genera are often referred to as the subfamily Trochetinae. The presented molecular phylogenetic analysis, based on mitochondrial 12S rDNA sequences and nuclear ITS2 sequences, has revealed a sister relationship between Trocheta and Erpobdella rather than between Trocheta and Dina. Furthermore, the annulation pattern has proved to be inappropriate for the diagnosis of Dina and Trocheta. The taxon Trocheta bykowskii krasensehas been classified on the basis of its Trocheta-like annulation; however, according to the molecular phylogeny, it belongs to the Dina clade. A pair of diagnostic PCR primers were developed to identify unambiguously individuals with intermediate annulation. In summary, (1) the traditional genus diagnosis of Dina and Trocheta is no longer tenable, and the genera are not always morphologically distinguishable by traditional characters; (2) T. b. krasense Sket, 1968, should be re-classified as Dina krasensis; (3) the subfamily Trochetinae should be annulled because it does not represent a monophyletic assemblage.