On the morphology and taxonomy of Griphobilharzia amoena Platt and Blair, 1991 (Schistosomatoidea), a dioecious digenetic trematode parasite of the freshwater crocodile, Crocodylus johnstoni, in Australia

Abstract

Griphobilharzia amoena Platt and Blair, 1991 was originally described as a dioecious trematode, parasitic in the circulatory system of the Australian freshwater crocodile, Crocodylus johnstoni, with the female completely enclosed in a gynecophoric chamber of the male and the 2 worms oriented anti-parallel to each other. A recent publication questions the original description, arguing that G. amoena is monoecious and, as a consequence, the species was transferred to Vasotrema Stunkard, 1928 (Spirorchiidae) as Vasotrema amoena n. comb. We provide photomicrographic evidence that the original description of G. amoena is correct and that Griphobilharzia Platt and Blair, 1991, is a valid monotypic genus containing G. amoena. An accurate understanding of the anatomy of G. amoena is not trivial and has implications for revealing the complex origins and evolution of the dioecious condition within the Schistosomatoidea.