Phylogenetic utility of the geometric model of the body form in leeches (Clitellata: Hirudinida)

Architectonics of the leech body constitute a source of promorphological characters which have been used for modeling. A geometric model of the leech body form was applied in a phylogenetic analysis for the estimation of the utility of morphometric data in the reconstruction of the history of Hirudinida. A cladistic analysis included species representing all main ecological groups of leeches. In the analysis the morphometric data were used as non-discretized mean values and as mean values coded with the gap-weighting method. Obtained phylogenetic trees were compared with cladograms generated based on combined data sets including discrete qualitative morphological characters as well as known molecular phylogenies of leeches. The study demonstrates that the morphometric characters provide additional evidence for the confirmation of monophyletic groups within Hirudinida. Thus, the morphometric data resulting from the geometric model of the leech body form appeared to be applicable for the reconstruction of leech phylogeny