Thursday, December 17, 2015

Another new frog: Xenopus eysoole

African clawed frogs of the genus Xenopus (especially Xenopus leavis) are used as model organisms for biological research. One would assume we know already the number of species in that group and other aspects of their diversity such as where they live and how they are related to one another. However, that is not the case. Researchers have now discovered half a dozen new species of the African clawed frog, and added back another to the list of known species. 

These clawed frogs, found in west and central sub-Saharan Africa, live in slow moving or stagnant water and are characterized by flattened bodies, vocal organs which can produce sound underwater, and claws on their first three toes.

One of the new species was named in consultation with the Fon of Oku and his advisors. Its name was derived from the Oku language. Roughly translated, the word eysoole (pronounced “ee-su-lay”) means “it will jump so hold it tightly,”.

For the experts: African clawed frogs, genus Xenopus, are extraordinary among vertebrates in the diversity of their polyploid species and the high number of independent polyploidization events that occurred during their diversification. Here we update current understanding of the evolutionary history of this group and describe six new species from west and central sub-Saharan Africa, including four tetraploids and two dodecaploids. We provide information on molecular variation, morphology, karyotypes, vocalizations, and estimated geographic ranges, which support the distinctiveness of these new species. We resurrect Xenopus calcaratus from synonymy of Xenopus tropicalis and refer populations from Bioko Island and coastal Cameroon (near Mt. Cameroon) to this species. To facilitate comparisons to the new species, we also provide comments on the type specimens, morphology, and distributions of X. epitropicalis, X. tropicalis, and X. fraseri. This includes significantly restricted application of the names X. fraseri and X. epitropicalis, the first of which we argue is known definitively only from type specimens and possibly one other specimen. Inferring the evolutionary histories of these new species allows refinement of species groups within Xenopus and leads to our recognition of two subgenera (Xenopus and Silurana) and three species groups within the subgenus Xenopus (amieti, laevis, and muelleri species groups).

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