Orientobilharzia Dutt & Srivastava, 1955 (Trematoda: Schistosomatidae), a junior synonym of Schistosoma Weinland, 1858.

In the last few decades, phylogenetic studies of the family Schistosomatidae based on molecular markers have revealed that members of the genus Orientobilharzia Dutt & Srivastava, 1955 belong within Schistosoma Weinland, 1858. In this study, the original descriptions and redescriptions of Orientobilharzia species and related revisions are reviewed, and it is confirmed that the morphological characters correspond with the results of the molecular studies. The two genera differ only in the number of testes; however, this character varies to a large extent within particular genera of the subfamily Schistosomatinae and cannot be used to justify the separation of Orientobilharzia from Schistosoma. Also, we have verified claims suggesting the synonymy of certain species of Orientobilharzia; the four valid species of this genus are transferred to Schistosoma and two new synonymies are formally presented. The following nomenclatural changes are made: Schistosoma Weinland, 1858 [syn. Orientobilharzia Dutt & Srivastava, 1955 (syn. nov.)]; Schistosoma bomfordi Montgomery, 1906 (comb. restit.); S. turkestanicum Skrjabin, 1913 (comb. restit.) [syns Ori. turkestanica var. tuberculata (Bhalerao, 1932) (syn. nov.) and Ori. cheni Hsü & Yang, 1957 (syn. nov.)]; S. dattai (Dutt & Srivastava, 1952) n. comb.; and S. harinasutai (Kruatrachue, Bhaibulaya & Harinasuta, 1965) n. comb. The generic diagnosis of Schistosoma is amended and a revised key to the subfamily Schistosomatinae Stiles & Hassall, 1898 is presented.