Comprehensive DescriptionRead full entry
Xenopus longipes is a small sized frog with a snout-vent length ranging from 32 – 36 mm in females and 28 – 31 mm in males. It is one of only two described frog species that are dodecaploid (the other being X. ruwenzoriensis), resulting in a chromosome number of 108 (Tinsley and Kobel 1996), and is one of the two smallest species in the genus Xenopus (the other being X. itombwensis; Evans et al. 2008). Xenopus longipes has a pear-shaped body with relatively long, thin limbs. The feet are conspicuously large with long and slender toes; this characteristic contributes to its scientific name which means “long foot” in Latin. As in other species of the Xenopus fraseri subgroup, the metatarsal tubercle has a prominent keratinous claw and the first three toes terminate in keratinous claws. It has large, distinctive eyes and the lower eyelid only covers about 1/3 of the eye. The subocular tentacles are relatively short. There are 8 – 10 lateral line plaques around each eye and 15 – 17 extending from the eye to the cloaca. Xenopus longipes has rough skin due to its many small keratinized spinules, which tend to be more densely packed in males than females (Loumont and Kobel 1991). Xenopus longipes was described as having an “emaciated” appearance in its initial scientific description and wild-caught animals since then look similar. However, animals in captivity readily put on weight suggesting that this appearance is not an intrinsic part of their biology and may be due to environmental conditions in Lake Oku (Loumont and Kobel 1991; Blackburn et al. 2010).
Xenopus longipes is distinguished from other small 4-clawed Xenopus species (including X. fraseri and X. pygmaeus) by its small size, ploidy (dodecaploid), large feet with elongate toes, and a distinctive orange or yellow coloration on the ventral surface in living specimens. It is further differentiated from other Xenopus species by osteological features including paired nasal bones (Loumont and Kobel 1991).
In life, Xenopus longipes has a golden-brown to chocolate-brown dorsum and a ventral side that is orangey or yellow. Both surfaces are covered in small black spots (melanophores) and some have larger, irregularly shaped black spots on the dorsal side. The ventral surface of the thighs and throat is amber (Loumont and Kobel 1991). Coloration of captive animals may differ from those in the wild, especially by having less bright ventral coloration (Blackburn, personal communication).
The color of the dorsum can vary highly between specimens. Some lack the irregularly shaped black spots or may only have several on the shoulders and head. Some specimens have so many melanophores on the ventral surface and throat that they appear black with a slightly gray-orange backdrop (Loumont and Kobel 1991).
The species authority is: Loumont C., and Kobel H.R. 1991. Xenopus longipes sp. nov., a new polyploid pipid from western Cameroon. Revue Suisse de Zoologie 98(4): 731-738.
Based on its distinct genetic and osteological features, Xenopus longipes was initially placed in its own subgroup (Loumont and Kobel 1991). However, recent phylogenetic work places X. longipes as a member of the larger X. fraseri subgroup that contains several other allopolyploid species in Cameroon, including X. amieti and X. boumbaensis (Evans et al. 2004, 2005, 2011).
Xenopus longipes has feet that are conspicuously large with long and slender toes; this characteristic contributes to its scientific name which means “long foot” in Latin (Loumont and Kobel 1991; Blackburn et al. 2010).