Xenopus muelleri (Peters, 1844)
Müller’s Platanna, Tropical Platanna, Müller’s Clawed Toad, Müller se Platanna (A), Tropiese Platanna (A)
Currently accepted name: Xenopus muelleri
Red listing status: Least Concern
Photo by Verburgt L.; Enviro-Insight CC, 2013. URL: FrogMAP: 2165
The distribution of X. muelleri in sub-Saharan Africa is divided into two distinct areas containing animals that are morphologically similar but probably represent allopatric sibling species (Kobel et al. 1996). One of these forms, X. muelleri-East, extends from southeastern Kenya to South Africa, and is the only form in the atlas region. This form includes the type material (from Mozambique), and hence is hereafter referred to as X. muelleri.
Within the atlas region, this species is confined to low-lying areas in northern and eastern Limpopo Province, eastern Mpumalanga and Swaziland, and northeastern KwaZulu-Natal, which form the western and southern limits of the Mozambique plain. Although Fischer et al. (2000) recorded mixed populations and hybridization between X. muelleri and laevis in Mpumalanga (2430BD), the two species are largely allopatric.
The ranges of X. muelleri and laevis are separated by the 18°C mean July isotherm, with muelleri part of a tropical faunal assemblage north and east of this climatic boundary, and laevis part of a non-tropical assemblage distributed to the south and west of the isotherm (Poynton 1964; Poynton and Broadley 1991). It is possible that the distribution of the species reflects differences in temperature tolerance: X. laevis appears to be able to tolerate a wider range of environmental temperatures than X. muelleri, which is more tolerant of high temperatures (Tinsley et al. 1996; see discussion under Habitat).
The atlas data can be regarded as reliable as X. muelleri can be easily distinguished, morphologically, from X. laevis.
X. muelleri inhabits all types of water bodies, including lowland rivers, lagoons, dams and pans (Poynton and Broadley 1985a), mainly in the Grassland and Savanna biomes. It is seldom found in pristine forest habitats, but readily moves into deforested areas (Tinsley et al. 1996).
X. muelleri and X. laevis do not appear to differ with regard to water-quality preferences or requirements. The apparent difference in temperature tolerance does not seem to apply in southern Namibia, where X. laevis occurs at temperatures at least as high as those from which it is apparently excluded in the east (Tinsley et al. 1996). A possible explanation is that X. laevis uses cool refugia within high temperature water bodies. This has been observed in extralimital populations of X. laevis (pers. obs.). Absence of such refugia from some sites would explain the observations of Lambiris (1989a) and Poynton and Broadley (1985a) that the two species are rarely found at the same site.
Little is known specifically about the life history of X. muelleri, although much can be inferred from the characteristics of the rest of the genus. Like other Xenopus, they are known to move en masse, even under dry conditions (Tinsley et al. 1996). Loveridge (1953a) found them aestivating in the mud of a dried pond.
Prey items include beetles, beetle larvae and frogs’ eggs (Barbour and Loveridge 1928), while predators include Hammerkop Scopus umbretta (Loveridge 1953a), Green Water-snake Philothamnus irregularis (Sweeney 1961) and Barbel Clarias gariepinus. X. muelleri has been observed leaving the water to escape barbel (L.R. Minter pers. comm.)
X. muelleri is not threatened, and does not warrant conservation action.
Current distribution map
Undated records; pre-1996; 1996 to 2002; 2003 to present
FrogMAP. 2019. Xenopus muelleri (Peters, 1844). Animal Demography Unit. Accessed from http://frogmap.adu.org.za/?sp=1060; on 2019-05-19 10:05:57.
Minter L.R., Burger M., Harrison J.A., Braack H.H., Bishop P.J. & Kloepfer D. (eds). 2004. Atlas and Red Data book of the frogs of South Africa, Lesotho and Swaziland. SI/MAB Series no. 9. Smithsonian Institution, Washington, D.C. Published by the Smithsonian Institution and the Avian Demography Unit (now Animal Demography Unit).