Cannatella,D.C and Trueb,L. "Evolution of Pipoid Frogs: Intergeneric Relationships of the Aquatic Frog Family Pipidae (Anura)" Zoological Journal of the Linnean Society 94 (1): 1-38 (1988) [Xenopus tropicalis and epitropicalis transferred to Silurana]

de Sa, R.O. and D.M. Hillis (1990). Phylogenetic relationships of the pipid frogs Xenopus and Silurana: an integration of ribosomal DNA and morphology. Mol. Biol. Evol. 7 (4): 365-376. The genus Silurana was resurrected by Cannatella and Trueb (1988) to accomodate the species in the Xenopus tropicalis group. Cannatella and Trueb (1988) believed the members of the Xenopus tropicalis group were more closely related to Hymenochirus, Pipa, and Pseudhymenochirus than they were to to other species of Xenopus. de Sa and Hillis (1990) refuted this phylogenetic placement of the Xenopus tropicalis group; instead, they found that Xenopus tropicalis and Xenopus epitropicalis were more closely related to other Xenopus than to Hymenochirus, Pipa, and Pseudhymenochirus. de Sa and Hillis also noted that Xenopus tropicalis and X. epitropicalis are sister-species, forming a monophyletic group which can be recognized as the genus Silurana. Silurana and Xenopus are recognized as sister-taxa, forming the subfamily Xenopodinae. Hymenochirus, Pipa, and Pseudhymenochirus remain in the subfamily Pipinae. The Xenopodinae and Pipinae constitute the Pipidae.

Cannatella,D.C. and de Sa,R. "Xenopus laevis as a model organism." Systematic Biology 42 (4) 476-507 (1993)

Silurana is sometimes represented as a genus separate from Xenopus -- we list it as a subgenus of Xenopus, following current usage in the literature. Both taxonomic schemes reflect the same phylogenetic tree, the only difference is in the assignment of the genus rank and the preferred scientific name of the Silurana species.