A typical large and compact toad with a warty skin. SVL of adult males 62–91 mm, females 70–130 mm. Large prominent kidney-shaped or parallel parotid glands, with a relatively smooth appearance because the warts are quite flat in this region. The large tympanum reaches 0.7 to, occasionally, 1.5 of the eye diameter. The tympanum shows a shallow circular depression. Therefore one might get the impression of a ring surrounding the ear. Males have a single subgular vocal sac, enlarged thenar tubercles and black nuptial pads on the outer faces of the first and second fingers, the latter are often less well-defined. The horny tips of the warts are apparently more pointed on males. However, these horny asperities are usually flat. The hind limbs have traces of webbing. The inner metatarsal tubercle reaches 0.5–1 of the length of the shortest toe. These toads have only few subdigital tubercles, which are less conspicuous in older specimens than in adult B. maculatus.
According to Inger & Greenberg (1956), male B. regularis have most often a single, sometimes paired, lateral slit in the floor of the mouth that forms the connection to the median, subgular vocal sac. Nuptial pads of breeding B. regularis males consist of densely pigmented clusters of asperities on the first, second, and third fingers and on the median part of the inner palmar tubercle.
Voucher specimens: SMNS 8947 1–3; SMF 78623; SMNS 8988, Ananda, Ivory Coast.
Coloration: Dark olive brown basic dorsal color, often turning lighter towards the venter. The skin between the tiny warts on the flanks often appears almost black. This toad also contains numerous dark patches on the upper lip, on the eyelids, and on the dorsal parts of the extremities. On the back, these dark patches are often arranged more or less symmetrically. The body axis is often highlighted by a light vertebral stripe which appears rather distinct on young animals but usually fades when they mature, turning to the same color as the back. Often pale patches are present on the back, too. The venter is uniform white to beige, the throat of males is black. According to Tandy et al. (1985), some animals also show dark markings on their venter. Preserved animals usually do not show any change of color. However, specimens tend to fade as time goes by.
Voice: A lengthy rattling sound, lasting 0.9 sec and composed of two elements which are repeated continuously. The initial element comprises numerous pulses (0.01 sec) separated by pauses (0.02 sec) and lasts about 0.4 sec. After a pause of 0.05 sec, the second element follows, lasting 0.5 sec. As the former, it is made up of pulses of 0.01 sec, but these are separated by longer pauses of 0.03 sec.
According to Tandy et al. (1985), the calls vary considerably depending on temperature and the animals size. These authors give a frequency of 0.3 to 2.5 kHz. The dominant frequency of the advertisement call in Ethiopian B. regularis is 0.5–1.6 kHz (Tandy et al. 1982). The calls published by Amiet (1976a) are similar to those of the Comoé toads. The calls of Serengeti toads published by Wickler & Seibt (1974) and assigned to B. regularis by them, are supposed to be those of B. gutturalis (Van Den Elzen & Kreulen 1979). The call published by Schiøtz (1964c) is most probably that of B. maculatus.
Noble (1924) reported that female toads were answering the male call "wook-wook" with a sound like "woop" followed by a quick "wop-wop". However, it is not sure if that observation was really on B. regularis, e.g. they describe the vocal sac of the male as reaching twice the size of the head, and being bluish in color.
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Angola, Benin, Burkina Faso, Cameroon, Central African Republic, Chad, Congo, Congo, the Democratic Republic of the, Egypt, Equatorial Guinea, Eritrea, Ethiopia, Gabon, Gambia, Ghana, Guinea, Guinea-Bissau, Kenya, Liberia, Malawi, Mali, Mauritania, Niger, Nigeria, Rwanda, Senegal, Sierra Leone, Sudan, Tanzania, United Republic of, Togo, Uganda
This species is widespread in savanna regions south of the Sahara. According to Hulselmans (1970), typical B. regularis are found in a region stretching from Senegal through West Africa to Central Africa and through North Africa to Egypt. In particular, this toad has been recorded from the following countries: Senegal, Gambia, Guinea Bissau, Sierra Leone, Liberia, Guinea, Mali, Burkina Faso, Ivory Coast, Ghana, Benin, Niger, Nigeria, Cameroon, ?Equatorial Guinea, Gabon, Angola, ?Congo, R.D. Congo, Chad, Central African Republic, Algeria, Libya, Egypt, Sudan, Ethiopia, Eritrea, Uganda, Rwanda, Kenya, ?Tanzania, ?Malawi (Günther 1895, ?Boulenger 1906, ?Nieden 1908, 1910b, ?Barbour 1911, ?Chabanaud 1919b, Noble (1924), ?Scortecci 1929, ?Barbour & Loveridge 1930a, ?Parker 1930, 1936a, c, ?Loveridge 1929, 1933, 1936, 1955c, Witte 1934, 1941, ?Sanderson 1936, ?Andersson 1937, ?Mertens 1938a, 1940, 1955, Monard 1940, Laurent 1952e, 1964b, 1972c, ?Lamotte & Zuber-Vogeli 1954a, ?Winston 1955, Guibé & Lamotte 1958a, Taylor & Weyer 1958, ?Schmidt & Inger 1959, ?Schiøtz 1963, 1964a, b, 1966, 1967, 1969, Perret 1966, 1977a, Barbault 1967, 1974d, 1984, Lamotte 1967b, 1969, ?1971, 1998, Urban 1967, Keith 1968, Vuattoux 1968, Walker 1968, Amiet & Perret 1969, Euzet et al. 1969, Maeder 1969, ?Wake & Kluge 1969, Hulselmans 1970, 1978, Lescure 1971, Perret & Amiet 1971, Amiet 1973a, 1976a, ?Stevens 1974, Böhme 1975, 1978, 1994c, Miles et al. 1978, Joger 1981, 1982, 1990, Tandy & Keith 1982, Tandy et al. 1982, 1985, Frost 1985, Schätti 1986, Böhme & Schneider 1987, Hughes 1988, Gruschwitz et al. 1991a, ?Fischer & Hinkel 1992, Duellman 1993, ?Pickersgill 1994, Böhme et al. 1996, Rödel 1996, 1998b, Largen 1997a, 1998).
This species is encountered all over the national park, but it seems to be connected more closely to savanna habitats than B. maculatus. B. regularis is generally considered to be a savanna species (e.g. Loveridge 1955a, Schiøtz 1967, Walker 1968, Frost 1985, Tandy et al. 1985, Böhme et al. 1996) which also colonizes the rainforest zone along clearings and roads (e.g. Amiet 1976a, Joger 1981, Hughes 1988, Böhme 1994c). It is a typical synanthropic animal (e.g. Perret 1977a, Joger 1981, Gruschwitz et al. 1991a). In the northernmost part of its range, this toad penetrates far into the Sahel region along the rivers (Joger 1981). It possibly even reaches various oases of the Sahara (Tandy et al. 1985). Having colonized a broad range of habitats including moist Guinea savanna, Sudan savanna, Sahelic savanna, dry forests, the edges of rainforests, human settlements, swamps and even montane grassland, this species must be regarded as highly adaptable (e.g. Schiøtz 1963, Perret 1966, Lamotte 1967b, Hulselmans 1970). Only true rain forest areas are virtually avoided (Amiet 1976a). In East and South Africa, the species is replaced by B. gutturalis, and in more arid parts of its northern range by B. xeros (Tandy et al. 1985). According to these authors, the occurrence of B. regularis seems to depend on a certain minimum of humidity.
Life History, Abundance, Activity, and Special Behaviors
Spawn: Most probably, it is quite similar to that of B. maculatus, but we have not yet got egg strings from known individuals.
At Lamto, females produced 10055 ± 2885 eggs (diameter: 1.3 mm, N = 11; Barbault 1984). According to Fischer & Hinkel (1992), the eggs are laid in a double string. However, the toad illustrated in this publication, shows parotids which are rather warty for a B. regularis. Spieler & Linsenmaier (1999a) give clutch sizes from 9000–13000 eggs.
Tadpoles: Since I have not yet observed spawning B. regularis, and amplectant pairs kept in captivity never went to spawn, the tadpoles of this species have not been positively documented so far. All the toad tadpoles I have examined are more or less similar to each other. Viewed by means of a scanning electron microscope, the oral discs of toad tadpoles whose parents could not be identified showed a caudad double row of papillae. The keratodont formula corresponded to that of B. maculatus tadpoles. The borders of the horny beaks were serrated. Compared to the measurements of trueB. maculatus tadpoles, the width of a single tooth was 1/3 of its length, and therewith less slender than in B. maculatus with known parents. Furthermore, the teeth were more sharply pointed. The proximad extension of these tips was less considerable. These larvae might have been B. regularis tadpoles. Even if these features should prove to be characteristic of this species, they may be supposed to be rather useless for identification in the field as the tadpoles are quite tiny. Tadpoles of this species possibly do not aggregate when predators are present (compare B. maculatus).
On 23.1.1999 I collected rather large Bufo-tadpoles beneath stones in the Comoé river. These tadpoles possessed the usual keratodont formula (1 / 1 + 1 // 3), and were brown in color, with a white spotted tail. The microhabitat was shallow and nonrunning water near the river bank. None of the tadpoles aggregated, despite the fact that a lot of predators were present (fish, dragonfly larvae, crayfish). In the same area I found other, aggregated Bufo tadpoles. In contrast these tadpoles were all black and much smaller. I therefore conclude that the larger ones might have been B. regularis. The largest tadpole measured about 23 mm (TL) and thus clearly exceeded the known size of B. maculatus tadpoles.
Perret (1966) gives the keratodont formulae 1 / 1 + 1 // 3 or 1 / 1+1 // 1 + 1 / 2. The former has also been published by Lamotte & Zuber-Vogeli (1954a), Guibé & Lamotte (1958a) and Lamotte & Xavier (1981), respectively. The single row of papillae shows a conspicuous rostral and caudal gap. Immediately in front of the corners of the mouth, the papillae are arranged in two rows. The largest tadpole ever found measured 21 mm (TL), and the SVL of freshly metamorphosed animals was 9–11 mm. Considering the sizes of adult toads, the animals examined by these authors were almost certainly B. regularis. Winston (1955) gives a SVL of 5 mm for metamorphosed young (but compare below) whereas Chabanaud (1921) reports 9 mm.
Single individuals are encountered on the riverside at the end of the dry season. Regarding the sporadic records of amplectant pairs observed at the river, these are likely to spawn at these sites, too. I never found spawning B. regularis at savanna ponds, but I would not exclude that those habitats are equally used for breeding purposes, all the more as adult toads found in the savanna are almost invariably B. regularis which are considerably less common in forest habitats than B. maculatus. Breeding occurred during the dry season (Joger 1981) in rivers (Böhme et al. 1996). Potential breeding sites also comprise almost any kind of water bodies, from shallow puddles to lakes and rivers, all of which may be either permanent or temporary (Tandy et al. 1985).
The latter authors give two main breeding periods for West Africa: the former in the early rainy season, and the latter, which is generally less important, in the final phase of that season. Amiet (1976a) reports that B. maculatus chooses more exposed calling sites than B. regularis. We never observed this difference. B. regularis is mainly nocturnal throughout the year. By day adult individuals were only observed during heavy rainfall. Exceptions are young toads, which inhabit rather humid places close to Inselbergs, and forage for prey during the day.
Sanderson (1936) describes bright yellow males which he observed during the breeding season (see B. maculatus). Perret (1966) made the same observation, but he writes that similar males were never found within B. maculatus. However, this observation at least does not apply to the Comoé National Park. Variations of the body length possibly correspond to the average amount of rainfall (Tandy et al. 1985), with smaller sizes connected with more arid conditions. At first sight, this phenomenon appears rather illogical regarding the unfavorable ratio between body volume and body surface, but the authors might be right in assuming that smaller animals will find a far broader range of appropriate refuges and therewith profit from their smaller size in the respective habitats.
According to Lescure (1971), the prey of B. regularis often includes ants, beetles and bugs. Noble (1924) reports arthropods and predominantly ants and termites as prey. The more passive hunting toads apparently select their prey by means of its size and activity. Barbault (1974d) mainly found ants in dissected specimens. Inger & Marx (1961) report on a diet comprising ants, beetles, termites, spiders, orthopterans, butterflies and flies, with variations of the diet spectrum depending on the respective seasons and altitudes. If the weather happens to be rather wet, the proportion of termites increases considerably. According to Lamotte (1983), this species has specialized on ants.
Most probably, the ecological studies presented by Chapman & Chapman (1958) are not based on B. regularis but on B. gutturalis. Winston (1955) provides some data concerning the development of B. regularis. However, these data, e.g. sizes of mature males, are likely to be based on two different species, including B. maculatus. The almost incredible period of development, that is said to last 122–143 days at a water temperature of 30 °C, almost certainly results from inappropriate keeping conditions. This author carried out his experiments in order to use these toads for pregnancy tests similar to those with Xenopus laevis.
This account was taken from Rödel, M.-O. (2000), Herpetofauna of West Africa vol. I. Amphibians of the West African Savanna, with kind permission from Edition Chimaira publishers, Frankfurt am Main.
For references in the text, see here
Rödel, M. O. (2000). Herpetofauna of West Africa, Vol. I. Amphibians of the West African Savanna. Edition Chimaira, Frankfurt, Germany.
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 (2002-01-14)
Species Account Citation: AmphibiaWeb 2002 Sclerophrys regularis: Common African toad <http://amphibiaweb.org/species/268> University of California, Berkeley, CA, USA. Accessed Oct 17, 2017.
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Citation: AmphibiaWeb. 2017. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 17 Oct 2017.
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