© 2016 Dr. Joachim Nerz (1 of 8)
A medium-sized clawed frog with button-like protruding eyes situated dorsally. Body flattened. Adults measure 38–60mm (SVL). The subocular tentacles are well developed, reaching about 0.6–1 of the eye diameter. The skin is almost smooth. Starting at the posterior border of the eye, a double line of elongate unpigmented flat sensory tubercles (lateral line sense organs) is arranged in roughly alternating order. The outer line comprises 20–29 tubercles set at right angles to the body axis. The inner one runs parallel to the latter, comprising about 16–20 tubercles. Furthermore, 3–7 pairs of these tubercles appear in the neck region, and 10–14 ones are found on the border of the lower jaw, set at right angles to the mouth. Like all of the dorsal surface, this part of the skin is scattered with numerous minute asperities which are equally unpigmented. Some of these may also be found on the fingers which are covered with numerous minute grooves. On breeding males, the outer part of the fingers is black. The dermal lobes above the vent are better developed in females. The web of the hind limbs is fully developed. Toes 3–5 have black horny claws. Metatarsal tubercle without claw. 2n = 36.
According to Stewart (1967), males from Malawi reach a SVL of 58 mm, females 72 mm. Concurring measurements were published by Nieden (1923), Poynton (1964a), Arnoult & Lamotte (1968), Lamotte & Xavier (1981) and Lambiris (1988). Poynton & Broadley (1985a) even specify a SVL of up to 80 mm. Smaller frogs, concerning animals from Cameroon, were measured by Mertens (1938a); SVL: males 38 mm; females 57 mm) and by Perret (1966); SVL: males 40–49 mm; females 54–63 mm). Nieden (1915) mentions a specimen from Tanzania showing traces of a fourth claw.
Coloration: Dorsal parts of body and limbs drab olive with large black patches that are sometimes vaguely defined. The iris shows a silver-grey glimmer. The venter is whitish to orange yellow. Some darker patches occasionally appear on the throat and on the thighs. A single female had the belly scattered with black spots. Distinctive ventral designs were reported from Ghanian frogs (Poynton 1964c). According to Loumont (1984), the dorsal patches of animals from Tanzania, Malawi and Zimbabwe are often arranged in two longitudinal rows. Mertens (1955b) mentions a female from Tanzania whose venter showed smoky-gray patches and a young specimen whose venter was plain white. In alcohol the dorsum turns almost completely gray olive, and the original black patches are hardly visible. The venter turns gray white, and black spots remain visible.
Voice: So far, it has not yet been registered at Comoé National Park. According to Schiøtz (1963), the call sounds like a rather low "pink-pink" resembling the sound produced by a spoon knocking against a pan. According to Vigny (1979), animals from Malawi produce a sequence of rattling "trra-trra" calls lasting 0.15–0.21 sec, the dominant frequency being 1.1 kHz. She describes two types of calls. Picker (1983) has also published sonagrams. These calls lasts 0.15 to 0.20 sec, comprising 5–6 pulses (dominant frequency: 0.8–0.9 kHz). Wager (1986) describes the call as "turrr", comparing it to the sound produced by a pencil vibrating against a glass pane. According to Lambiris (1988), two soft calls per second are uttered under water. Passmore & Carruthers (1995) report short "metallic" calls produced under water at intervals of 0.15 seconds. The vocal apparatus of the male has been examined by Loumont (1981).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Angola, Benin, Botswana, Burkina Faso, Cameroon, Central African Republic, Chad, Congo, Congo, the Democratic Republic of the, Gabon, Ghana, Kenya, Malawi, Mozambique, Namibia, Nigeria, South Africa, Sudan, Swaziland, Tanzania, United Republic of, Uganda, Zambia, Zimbabwe
This species inhabits savanna ponds of highly variable size. During the dry season, X. muelleri is found at the banks of rivers. The data found in the available literature almost exclusively refer to savanna habitats (e.g. Schiøtz 1967, Walker 1968, Joger 1981, Hughes 1988, Böhme et al. 1996). Only Schiøtz (1963) mentions a dry forest habitat where X. muelleri occurs in syntopy with Silurana tropicalis. However, the two species were never found in the same pond, thus resembling very much the situation in Comoé National Park. The data concerning the preferred habitat types are somewhat contradictory. For example, small ephemeral ponds are mentioned by Noble (1924), Loveridge (1933), Schiøtz (1963), Joger (1981, 1982) and Böhme et al. (1996), whereas Walker (1968), Broadley (1971), Lamotte & Xavier (1981), Poynton & Broadley (1985a), Lambiris (1988), and Passmore & Carruthers (1995) refer to permanent ponds and lowland rivers as preferred habitats. According to Channing (1989) X. muelleri in Namibia inhabits pans and deep pools, often even in the presence of large fish. Finally, Arnoult & Lamotte (1968) state
semi-permanent waters. It is very difficult to decide which habitat type is really preferred, as most studies exclusively refer to the actual state of the respective habitat, which may have appeared totally different as it was colonized by clawed frogs. Residuary puddles are mentioned quite regularly, but these are often situated in the dry beds of brooks and rivers. In the Comoé National Park, large but temporary pools are apparently preferred, at least during the breeding season.
Life History, Abundance, Activity, and Special Behaviors
Arnoult, J. and Lamotte, M. (1968). ''Les Pipidae de l'Ouest africain et du Cameroun.'' Bulletin de l’Institut fondamental d’Afrique noire, Série A, 30, 270-306.
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Lambiris, A. J. L. (1988). Frogs and Toads of the Natal Drakensberg, Ukhahlamba Series No. 3. University of Natal Press, Pietermaritzburg, South Africa.
Lamotte, M. and Zuber-Vogeli, M. (1953). ''Contribution a l'Ã©tude des batraciens de l'Ouest Africain I. Le dÃ©veloppement larvaires de Rana oxyrhynchus gribinguinensis Angel.'' Bulletin de l'Institut fondamental d'Afrique noire, SÃ©rie A, 15, 178-184.
Loumont, C. (1981). ''L'appareil vocal des males Xenopus (Amphibia Anura).'' Monitore Zoologico Italiano, N.S. Supplemento, 15(2), 23-28.
Loumont, C. (1983). ''Deux espèces nouvelles de Xenopus du Cameroun (Amphibia, Pipidae).'' Revue Suisse de Zoologie, 90, 169-177.
Loumont, C. (1986). ''Xenopus pygmaeus, a new diploid pipid frog from rain forest of equatorial Africa.'' Revue Suisse de Zoologie, 93(33), 735-764.
Loveridge, A. (1929). ''East African reptiles and amphibians in the United States National Museum.'' Smithsonian Institution, U.S. National Museum Bulletin, 151, 1-135.
Loveridge, A. (1930). ''A list of the Amphibia of the British territories in East Africa (Uganda, Kenya Colony, Tanganyika Territory, and Zanzibar), together with keys for the diagnosis of the species.'' Proceedings of the Zoological Society of London, 1930, 7-32.
Loveridge, A. (1932). ''New frogs of the genera Arthroleptis and Hyperolius from Tanganyika Territory.'' Proceedings of the Biological Society of Washington, 45, 61-64.
Loveridge, A. (1935). ''Scientific results of an expedition to rain forest regions in Eastern Africa, I. New reptiles and amphibians from East Africa.'' Bulletin of the Museum of Comparative Zoology, Harvard, 79, 1-19.
Loveridge, A. (1941). ''South African frogs of the genus Hyperolius in the Museum of Comparative Zoology, Cambridge, Massachusetts.'' Annals of the Transvaal Museum, 20, 283-291.
Loveridge, J.P. (1976). ''Strategies of water conservation in Southern African frogs.'' Zoologica Africana, 11, 319-333.
Mertens, R. (1938). ''Herpetologische Ergebnisse einer Reise nach Kamerun.'' Abhandlungen Senckenbergischen Naturforschenden Gesellschaft, 442, 1-52.
Mertens, R. (1968). ''Zur Kenntnis der Herpetofauna von Kamerun und Fernando Poo.'' Bonner Zoologische Beitrage, 19, 69-84.
Nieden, F. (1908). ''Die Amphibienfauna von Kamerun. Mit einer Bestimmungstabelle.'' Mitteilungen des zoologischen Museums Berlin, 3, 489-518.
Nieden, F. (1923). ''Anura I, Subordo Aglossa und Phaneroglossa sectio 1 Arcifera.'' Das Tierreich, 46, 1-584.
Nieden, F. (1926). ''Anura II, Engystomatidae.'' Das Tierreich , 49, 1-110.
Noble, G.K. (1926). ''The importance of larval characters in the classification of South African Salientia.'' American Museum Novitates, 237, 1-10.
Passmore, N.I. and Telford, S.R. (1981). ''The effect of chorus organization on mate localization in the Painted Reed Frog, Hyperolius marmoratus.'' Behavioral Ecology and Sociobiology, 9, 291-293.
Perret, J.-L. (1971). ''Les espèce du genre Nectophrynoides d'Afrique (Batraciens Bufonides).'' Annales de la Faculté des Sciences du Cameroun, 6, 99-109.
Pfeffer, G. (1893). ''Ostafrikanische Reptilien und Amphibien, gesammelt von Herrn Dr. F. Stuhlmann im Jahre 1888 und 1889.'' Jahrbuch der Hamburgischen Wissenschaftlichen Anstalten, 1893, 4(1), 69-105.
Picker, M.D. (1983). ''Hormonal induction of the aquatic phonotactic responses of Xenopus.'' Behaviour, 84, 74-90.
Poynton, J.C. (1964). ''Relationships between habitat and terrestrial breeding in amphibians.'' Evolution, 18, 131.
Poynton, J.C. (1966). ''Amphibia of Northern Mozambique.'' Mems. Inst. Invest. cient. Mocamb., Ser. A, 8, 13-33.
Poynton, J.C. and Broadley, D.G. (1985). ''Amphibia Zambesiaca 2. Ranidae.'' Annals of the Natal Museum, 27, 115-181.
Rödel, M. O. (2000). Herpetofauna of West Africa, Vol. I. Amphibians of the West African Savanna. Edition Chimaira, Frankfurt, Germany.
Schiøtz, A. (1964). ''A preliminary list of amphibians collected in Ghana.'' Vedenskabelige Meddelelser fra Dansk Naturhistorisk Forening, 127, 1-17.
Vuattoux, R. (1968). ''Le peuplement du Palmier rônier (Borassus aethiopum) d’une savane de Côte d’Ivoire.'' Annales de l'Université d'Abidjan, Série E, 1, 1-138.
Wake, M.H. (1980). ''The reproductive biology of Nectophrynoides malcolmi (Amphibia: Bufonidae), with comments on the evolution of reproductive modes in the genus Nectophrynoides.'' Copeia, 1980(2), 193-209.
Written by M.O. Roedel (roedel AT biozentrum.uri-wuerzburg.de), Biozentrum der Universitaet, Lehrstuhl fuer Tieroekologie und Tropenbiologie, Wuerzburg
First submitted 2001-02-21
Edited by Vance Vredenburg (2008-02-03)
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