The Morphology and Development of the Monogenetic Trematode Sphyranura oligorchis (Alvey 1933) and the Description of Sphyranura polyorchis n.sp.

Abstract

The description of Sphyranura oligorchis (Alvey, 1933) and S. polyorchis n.sp. is presented together with an account of the development of the former. Study of the life history of S. oligorchis, and a review of the literature on the life cycles of the Monogenea, show that at a corresponding time in their development embryonic stages similar to Dactylogyrus are present. It is postulated that Dactylogyrus is near the primitive ancestral type of the Monogenea, and that all of the parasitic platyheminthes may have arisen from a common planula ancestor.