A key to the freshwater triclads (Platyhelminthes, Tricladida) of Herzegovina watercourses

Abstract

The aim of this paper is to describe morphological characteristics of freshwater triclads in Herzegovina and to provide a key for their identification based mainly on their external morphology. Our research is based on the freshwater triclads collected at 26 sites in Herzegovina, including 10 rivers, 6 springs and 1 lake.
Triclads were collected by hand and with the bait jar with a lid bearing many small perforations. Specimens were identified immediately after being collected or we transported them to the laboratory in termal containers with ice. The morphological features used for species identification in this key are: body coloration (color of the dorsal and ventral side), the size of the pharynx, the presence of tentacles and their location, number and position of the eyes in respect to each other and the body margin, and the shape of the head. Specimens were fixed using Steinmann’s fluid and conserved in 70 % alcohol. Inner morphological feature, shape of a penis, was used in determination of Polycelis tenuis and Polycelis nigra.
We collected a total of 11 species, belonging to 8 genera (Polycelis Ehrenberg, 1831, Crenobia Kenk, 1930, Phagocata Leidy, 1847, Planaria Müller, 1776, Dendrocoelum Örsted, 1844, Schmidtea Ball, 1974, Dugesia Girard, 1850, Girardia Ball, 1974) and 3 families.
The present study forms a baseline for future studies on the diversity and biogeography of Herzegovinian freshwater triclads.