The phylum Platyhelminthes is a major clade of worms, with about 29,000 species (after Zhang, 2011). It includes animals with diverse lifestyles, but a majority are parasites, grouped within the Neodermata. The free-living species inhabit marine, freshwater, brackish and terrestrial environments and form the paraphyletic “Turbellaria”, with about 6,500 described species in three main clades: Catenulida, Macrostomorpha and Rhabdocoela. Within the Rhabdocoela, Typloplanidae occurs all over the world and is one of the most species-rich families.