Diagnosis: Large, plump frog; typical color pattern; yellow dorsolateral ridges are broad and flat.
Description: A large, plump ranid with comparatively short hind legs. The largest male in Comoé National Park measured 77.4 mm, the largest female reached 62 mm (SVL). However, males are normally smaller than females. The snout is moderately pointed. The tympanum is clearly visible, reaching about 0.8 of the eye diameter. Males with paired lateral vocal sacs. Males with large glands on the ventral side of the upper arm. Distinct flat, large dorsolateral ridges running from the posterior eye border to the end of the body. Skin with large flat warts on the flank and posterior back regions, but smooth or finely granulated otherwise. Sturdy forelegs; thighs and lower legs measure just 0.38–0.45 of the SVL. The foot, including the longest toe, measures 0.7 of the SVL. Toes without discs; toe tips never larger than the subarticular tubercles. The inner metatarsal tubercle measures 0.4 of the shortest toe length. An outer metatarsal tubercle may be present. Webbing formula: 1 (1) or (0.5), 2 i/e (1–0.5), 3 i/e (2–1) or (1.5–1), 4 i/e (2), 5 (0.5).
Voucher specimens: SMNS 8949 1–2 + tadpoles; SMF 78625.
Coloration: The basic body color varies from drab pale brown to dark brown. The dorsum appears comparatively uniform, showing just several paler yellow spots in the anal region and on the thighs, producing, a mottled pattern. The iris is golden to orange. A pale yellow to pale orange stripe runs from the nostril across the eyelid and along the dorsolateral ridge to the body end. On the body, these slightly prominent bands are lined by dark brown to black borders. The upper lip is white, stretching further to the groin as a line of the same color with straight to slightly undulating black borders. The part of the snout between the above-mentioned lines and the tympanum is dark brown. The flanks show the same color as the back, bearing several flat yellowish warts with dark borders. Similar markings appear in the groin region, comprising somewhat larger yellow patches with dark borders. On the thighs, the black borders dissolve, forming dark meanders on a pale background. The latter is white on the inner faces of the thighs, but olive to brown on the outside. The lower legs are divided into two rather different sections by a pale longitudinal stripe with dark borders. The dorsal part is more or less uniform brown, whereas the lower sector is mottled in black or yellow brown. The feet and arms are light colored. Dark pigments are present only in the axillary region. The venter is whitish to light gray, with only the lateral regions of the belly and hind limbs being mottled with dark. Coloration in alcohol is generally similar to live coloration. However, yellow pigments usually turn white. In general the markings tend to fade out.
Voice: This frog regularly produces two different calls whose exact functions are still unknown. However, they are assumed to be advertisement calls. The more common one is a high-pitched hooting or barking "huhoot" lasting about 0.36–0.57 sec whose frequency ranges from 0.2–3 at the beginning to 1.80–2.75 kHz at the end. The second call is a long low grunting sound lasting 0.85–1.30 sec, consisting of many short pulses which lasts 0.01 sec, and are separated by intervals of 0.03 sec. At first, two different harmonies between 0.4–0.8 and 1.6–2.5 kHz seem to be produced (the sonagrams are far from perfect); however, they fuse within 0.4 sec, and the frequency now ranges from 0.4 to 2.8 kHz. The calls are often uttered irregularly, and the pauses occasionally last several minutes. Males obviously stimulate each other by their calls. Amiet (1973a) does not believe that the two calls have different functions. For Nigeria, Walker (1967) only mentions the "barking" sound. Perret (1977b) does not report on different calls either.
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Benin, Burkina Faso, Cameroon, Central African Republic, Congo, the Democratic Republic of the, Cote d'Ivoire, Eritrea, Ethiopia, Gambia, Ghana, Guinea-Bissau, Kenya, Malawi, Mali, Mozambique, Nigeria, Senegal, Sierra Leone, Somalia, Tanzania, United Republic of, Uganda, Zambia
Habitats: In the dry season, this species is encountered on river banks and in the savanna. During the rainy period, it is usually found in savanna ponds, very rarely in gallery forests. Generally, savanna habitats are quoted (Monard 1940, Lamotte 1967b, 1969, Schiøtz 1967, Lanza 1981). In West Africa, they include both humid Guinea savanna (Schiøtz 1962, Walker 1967, 1968, Hughes 1988) and more arid Sudan (Joger 1982, Hughes 1988) and Sahel savannas (Schiøtz 1962). At least, this species is supposed to demand rather open habitats, and its association with humid places is regularly highlighted. For example, Joger (1981, 1982) gives humid meadows near waters or inundation areas. Loveridge (1933) and Poynton (1964a) mention deep or open swamps overgrown with grass. Sanderson (1936) also describes marshy habitats. Amiet (1973a) found Amnirana. galamensis near deep waters surrounded by high vegetation. Perret (1977b) gives permanent deep waters as spawning sites. Walker (1967) even believes that this species is encountered rarely because of its preference for thick vegetation on the edges of water bodies. However, it is said to survive the dry season even in very dry habitats. According to Perret (1977b) frogs of this "genus" (compare "similar species") are mainly forest-dwellers which have colonized savanna habitats only secondarily.
Range: According to Frost (1985), this frog, whose name alludes to the Lac Galam in Senegal, inhabits the savannas south of the Sahara, from Senegal to Mozambique. In particular, this species has been recorded from the following countries: Senegal, Gambia, Guinea Bissau, Sierra Leone, Mali, Burkina Faso, Ivory Coast, Ghana, Nigeria, Cameroon, R.D. Congo, Congo, Central African Republic, Somalia, Eritrea, Ethiopia, Uganda, Kenya, Rwanda, Burundi, Tanzania, Zanzibar, Malawi, Zambia, ?Zimbabwe, Mozambique, ?South Africa (Nieden 1908, 1910b, 1915, Boulenger 1910, Chabanaud 1921, Scortecci 1929, Parker 1936c, Sanderson 1936, Andersson 1937, Loveridge 1930, 1933, 1936, 1942, 1955b, c, 1957, Parker 1930, Witte 1934, 1941, Mertens 1938a, Monard 1940, Laurent 1956b, Schiøtz 1963, 1964a, b, 1967, Poynton 1964a, c, 1991, Lamotte 1966, 1967b, 1969, Perret 1966, 1977b, Barbault 1967, 1984, Stewart 1967, Walker 1967, 1968, Amiet 1973a, Stevens 1974, Böhme 1978, Miles et al. 1978, Hoogmoed 1980, Joger 1981, 1982, 1990, Lanza 1981, Poynton & Broadley 1985b, Zug 1987, Branch 1988, Hughes 1988, Simbotwe 1988, Gruschwitz et al 1991a, Simbotwe & Mubemba 1993, Pickersgill 1994, Böhme et al. 1996, Rödel 1996, 1998b, Joger & Lambert 1997, Largen 1997a, 1998).
According to Loveridge (1957), the nominate form inhabits West and Central Africa, whereas Amnirana galamensis bravana is found in East and Southern Africa. The records concerning Zimbabwe and South Africa are rather doubtful, as the occurence of this species is confirmed neither by Wager (1986) nor by Lambiris (1989) or Passmore & Carruthers (1995).
Life History, Abundance, Activity, and Special Behaviors
Eggs: The eggs are deposited as a single layer comprising 1500–4000 eggs floating at the surface. Most egg films contain 2000–3000 eggs. They are spread out between aquatic plants or leaves of grass. Including jelly, the egg diameter varies between 5.5–7.1mm. The diameter of the egg itself measures 1.5–1.9 mm. The eggs have black and white poles. At Lamto, females produced 5135 + 2074 eggs (egg diameter: 1.7 mm; N = 3, Barbault 1984).
Tadpoles: The tadpoles hatch within two days, measuring approx. 6 mm and bearing exterior gills. The will stick to the jelly for at least another day. Within a few days, the body, which is very elongate initially, becomes more and more rounded. Dark spots develop all over the dorsum, but disappear as the tadpoles grow larger. At this stage, their keratodont formula is already complete: 1 // 2. The most caudad tooth row is situated on a thick lip. The horny teeth are elongate, each bearing two to three blunt tips. Two additional, more proximal hooks may be present. Horny beaks slender and slightly serrated. A few large papillae on both sides of the oral disc, and one to two papilla rows are situated caudad. Two dark longitudinal lines start at the caudad corners of the oral disc, fading out at the center of the body. The contrasting black patterns also fade on older tadpoles so that the animals usually show an inconspicuous brown or beige coloration. However, dark brown or blackish spots of a highly variable number and size may appear all over the body. At this stage the body shape takes on a more slender appearance again. The tail fin may either be transparent or bear numerous fine brown spots. It inserts after the very broad tail base, i.e. on a level with the vent. The yellow dorsolateral lines of metamorphosed frogs are already present on old tadpoles immediately before the forelegs emerge. The largest tadpoles measure approx. 60mm (TL).
Tadpoles reared in captivity proved to develop very slowly. Their hind limbs did not emerge before three months, and their forelegs three weeks later. Metamorphosis was completed within four months. In the wild, this process is assumed to take much less time. In 1992, I found the first young frog two months after the first male had called. Frogs reared in captivity were of the same size as the freshly metamorphosed specimens found in the field, i.e. 19–22mm.
According to Perret (1977b), the Amnirana galamensis tadpole described by Andersson (1937) is actually a Ptychadena larva. However, Andersson (1937) reports on tadpoles showing light dorsolateral ridges shortly before they metamorphosed. He also gives the keratodont formula 1 // 1 / 1 + 1. If Perret (1977b) knewonly the tadpole of Amnirana albolabris, his conjecture would appear understandable, as neither the body shape nor the oral disc of the latter show any similarity to A. galamensis (compare Lamotte et al. 1957). Loveridge (1933) assumed that the tadpoles he had described asA. galamensis were actually Pyxicephalus edulis.
Biology: Towards the end of the dry season, I found A. galamensis both under stones at the river banks and in crevices which had developed at the bottom of dry ponds. In Nigeria, this species is dug up rather often by local farmers (Walker 1967, 1968). According to Stevens (1974), some specimens probably hibernate in termite mounds. Walker (1967) reports on a male which began to call in the dry season when a garden was accidentally inundated. At Comoé National Park, some males will call as soon as the rainy season sets in. However, weeks or even months may pass until the frogs actually spawn. At several ponds, calling males were heard for months, but spawn was never detected. The calls are usually uttered at night. If the weather happens to be sultry or in periods of moderate rainfall, the two call types are occasionally heard during the day, too. The males usually hide between clumps of grass in the bank zone or sit in shallow water. Calling males were equally found in subterranean refuges or under dead wood. Calling males often sit very close to each other, but marked territorial behavior has also been observed (Spieler, pers. comm.). The factors triggering mating have not yet been discovered. I found clutches irregularly throughout the rainy season, both after and without actual rainfall.
Generally, the clutches were attached to aquatic plants growing in the shallow water. Established spawning sites are obviously used over and over again. Within a certain pond, the clutches are often found at one and the same site. Often, the egg films were shaded by scrub or trees growing on the banks. Savanna ponds of various sizes are acceptable, but larger ones are more likely to be chosen. Considerable calling and breeding aggregations are often established along temporary brooks. Very rarely, calling males have been observed at forest ponds, where I found only one single clutch.
Although, A. galamensis is a ubiquitous species, it never appears in large numbers. According to Schiøtz (1964a), the species was rather common on the Accra plain (Ghana) in June. I heard its call in June in Burkina Faso (Böhme et al. 1996). A. galamensis is often encountered near waters, but I do not consider it at all as a mainly aquatic species, as described by Poynton & Broadley (1985a). According to Loveridge (1933) and Walker (1967), it is a very timid species which flees in great leaps. However, we have observed that this frog is really phlegmatic, just fleeing when we were only some centimeters away. We cannot share the opinion of Loveridge (1933) who states that A. galamensis produces louder calls in sunny weather and stops calling when rainfall begins.
In the stomach of a dissected animal, Loveridge (1942) found a caterpillar and a locust, whereas Zug (1987) detected remains of various beetles. In 1936 Loveridgecited different arthropods as prey.
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), Post-Doc at the University of Wurzburg, Department of Animal Ecology and Tropical Biology, Wurzburg, Germany
First submitted 2001-05-02
Edited by Meredith Mahoney and Tate Tunstall (2003-02-17)
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