In this paper we report a new species of Dugesia of the family Dugesiidae from Madagascar, representing
the fourth species of freshwater planarian known from this global biodiversity hotspot. In some respects
the new species is aberrant, when compared with its congeners, being characterized by a head
with smoothly rounded auricles, a peculiar course of the oviducts, including the presence of a common
posterior extension, and by the asymmetrical openings of the vasa deferentia at about halfway along the
seminal vesicle. Further, it is characterized by a ventral course of the ejaculatory duct with a terminal opening,
very long spermiducal vesicles and unstalked cocoons. Its diploid chromosome complement with 18
chromosomes represents an uncommon feature among fissiparous species of Dugesia
