Elizabeth Scott et al (2013) re-examined the Pyxicephalus genus status by studying museum species used to describe previous species. As a result, they have revalidated P.angusticeps as a species and designated a lectotype (a specimen or group of specimens representing the type of that species) for P. edulis. Both P.angusticeps and P. edulis cohabit the Mozambique's Plains .
Following is summary of their key to the species:
1. Frog is P. angusticeps if odontoids are wider than they are long. If odontoids are longer than wide, go to 2.
2. Frog is P. adspersus if upper jaw is free of barring in adults. If barred, go to 3.
3.a. Frog is P. obbianus if tympanum width is greater than eye diameter and located less than 1/2 eye diameter distance to eye.
3.b. Frog is P. edulis if tympanum width is less than or equal to eye diameter and located more than 1/2 eye diameter distance to eyes; and the toes have moderate webbing.
Please note the above key was generated from adult museum specimens and authors did not include information that we hobbyists desire on how to differentiate the babies! You can use the above key with limitations and cross referencing to additional baby frog traits. Obviously; if breeder or source properly identifies parent or caught species, then it’s a done deal. But we all know how that usually goes .
Although not herpetologists ; Phillipe de Vosjoli and Robert Mailloux (2012) raise several points in African Bullfrog taxonomy based on current species trade and field observations. These include differentiating between P. edulis and a second Mozambique frog (now P. angusticeps) and mentioning possible different species from Tanzania and within what currently is known as P. edulis. If interested on these additional “unofficial” African Bullfrogs, read their reference . They do include lengthy descriptions and photos to illustrate their points .
So do we have 4 final African Bullfrog species or will some of the Vosjoli/Mailloux specimens acquire species status ? It’s a general consensus that the genus still requires DNA sequencing and other field and lab metric analysis before this topic can be wrapped-up. In the meantime, we should expect to encounter some African Bullfrogs that challenge fitting into Scott et al (2013) described 4 species. There is also no knowledge if any of the species that share areas can intermix and produce hybrid offspring. So post your pics, state frog source, and we will do our best to guess frog species and sex !
References:
Scott E. et al (2013) Revalidation of Pyxicephalus angusticeps Parry, 1982. (Anura: Natatanura: Pyxicephalidae), a bullfrog endemic to the lowlands of eastern Africa. Zootaxa 3599 (3) 2013 Magnolia Press.
Vosjoli P. and Mailloux R. (2012) Giant African Bullfrogs Life History and Captive Husbandry. Advanced Visions, Inc., CA USA.