A new species of the land planarian Issoca sheds light on the polyphyletic status of the genus (Platyhelminthes, Tricladida, Geoplaninae)

Abstract. A new species of the genus Issoca (Platyhelminthes, Tricladida, Geoplaninae) is described. Issoca assanga sp. n. presents the diagnostic features of the genus, with the exception of the relative position of the subneural parenchymal muscle layer with the cephalic retractor muscle, which are overlapped in the type species of the genus but are intersected in the new species. Rather than a polymorphic character, the relative position of these muscle layers might reflect the polyphyletic status of the genus.