A cave leech (Hirudinea, Erpobdellidae) from Croatia with unique morphological features

Croatobranchus mestrovi is a troglobitic leech from deep shaft-like caves in the Velebit Mountain, Dinaric karst, Croatia, living in cold (4-6 degreesC) water. Its oral sucker extends to form four pairs of triangular tentacles, each with about five finger-like papillae, but widening into a marginally crenulated disc when attached to a substrate. Pairs of stiff, finger-like lateral projections, probably gills, occur along the body behind the clitellum. Somites are simple five-annulate. Despite the unique head morphology and the presence of lateral outgrowths, the anatomy and 18S rRNA gene sequence of this species indicate that it is a member of the Erpobdellidae, closely related to Dina.