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A large and flat ranid containing protruding eyes, numerous dorsal warts, and a minute inner metatarsal tubercle. It has complete webbing between the toes and fingers.
A large dorsoventrally flattened ranid frog with a very warty skin whose eyes and nostrils are dorsally positioned (when viewed from above the eyes are contained within the outline of the head). Due to numerous glands, the skin is very slippery. SVL of adult males: 52–104 mm. SVL of the largest females measured in Comoé National Park was 65 mm (but see below). Weight of males is 24–84 g (x= 42.7), of females: 20–132 g (x= 53.5). Broad mouth. The border of the lower jaw has three tooth like structures. Oval vertical pupil. The distinct tympanum is bordered by a bulging supratympanal fold. It reaches 0.7–0.9 of the eye diameter. Males have paired lateral vocal sacs and considerably enlarged thenar tubercles. The skin of the throat surrounding the vocal sac slits is heavily folded. The warts on the flanks are usually arranged in longitudinal rows. 6–8 of these rows are very distinct on the backs of young specimens, too. The hind limbs are comparatively short but very muscular. Thighs and shanks reach 0.4–0.5 of the SVL, each. The shanks are usually longer than the thighs. The foot, incl. the longest toe, reaches 0.6–0.8 of the SVL. Many small tubercles on the posterior part of the thighs. The very tiny inner metatarsal tubercle just reaches 0.2–0.4 of the shortest toe length. Webbing is complete. The hands with trace of webbing.
A female measured by Loveridge (1955a) weighed 235 g at a SVL of 127 mm. Perret (1966) gives 68–110 (SVL) mm for males and 110–135 mm for females. The record is probably held by a female measuring 160 mm (see Schiøtz 1964a).
Voucher specimens: SMNS 8956 1–5 + tadpoles; SMF: 78630–32.
Coloration: The basic color of body and limbs is a yellowish green, olive or drab brown. Large dark green to blackish spots which occasionally form rows, are present on the back. Spots of the same color are present on the upper lip and on the extremities. A light green to yellow transverse line behind the eyes is always present in young frogs and usually in adult individuals, too. The outer parts of the thighs are marbled. The venter is white, sometimes marked with few black spots. The lower lips and the throat are mostly white, bearing very rarely some black spots. The vocal sacs are dark gray, light blue (Burton 1972) or cream (Loveridge 1955a). Böhme (1978), cites frogs with typical color pattern, and specimens whose basic color was brick red. In alcohol the venter turns drab gray. The patches are at most a little darker than the surrounding areas, remaining rather distinct on the extremities. The light transverse line behind the eyes remains visible.
The advertisement call is a slightly rising and rather low gnarling sound which lasts about 0.2 sec. It consists of several pulses, each lasting 0.01 sec, and separated by intervals of the same length. As all recordings have been jammed by the voices of other species, its frequency can only be estimated: it probably ranges from 0.2 to 2.1 kHz. Its dominant frequency seems to range from 0.8–1.2 kHz. If danger is imminent, young frogs will utter high-pitched cheeping sounds. This observation is confirmed by Amiet (1974b). The call published by Van den Elzen & Kreulen (1979) is almost identical: it also lasts 0.2 sec and consists of 12 pulses, its dominant frequency being 1–1.5 kHz. The intervals between calls last 1.1–1.4 sec.
Spawn: The eggs are attached singly or in small groups at the bottom or on stones in shallow water zones. The sticky jelly is soon covered by algae and detritus so that the eggs are hardly visible. The eggs diameter is approx. 5 mm. The egg diameter at the neurula stage is 3.2 mm.
Zug (1987) measured ovarian eggs. They measured 1.6–1.8 mm and already had black and white poles. Loveridge (1925) gives 2 mm for ovarian eggs. Parker (1936c) and Sanderson (1936) described the clutch as an enormous mass of floating eggs. However, these authors have almost certainly confused Hoplobatrachus eggs with those of another species (probably Phrynomantis microps).
The water temperature of the shallow ponds occasionally rose to 40 °C, particularly in rock-pools. In these habitats the tadpoles, which still have external gills at this stage, usually hatch within half a day. They measure 6.5 mm TL and 3 mm BL. In the aquarium, larvae reared at 30 °C and feeding on customary fish food grew very slowly. The oral disc began to develop 54 hours after hatching. Neither horny teeth nor nostrils were present at this stage. The external gills were still visible. At this stage the tadpoles measured 9.4mm (TL) and 4.2 mm (BL), respectively. At the age of 70 hours, they measured 12.7 mm (TL; BL: 4.7 mm). The external gills had been reduced, and the nostrils and oral disc were visible. Under natural conditions, their development may be completed within less than two weeks, but it often takes much longer, particularly in larger ponds.
In natural ponds, the tadpoles already show their characteristic oval shape after one day. Nostrils and eyes are placed dorsally on the snout and front. The oral disc is surrounded by bulging lips and has the following keratodont formulae: 2 / 1+1 // 1+1 / 2 or 2 / 2+2 // 2+2 / 2. The most caudad teeth are arranged in a double row. The horny teeth have only one tip. The horny beaks have a characteristic form: the upper one is serrated, and its center shows a conspicuous hook; the lower one is voluminous and serrated, and it shows two pointed extensions. The space between these two extensions exactly match the hook of the upper jaw. Short blunt papillae border upper and lower lips. The body shape of well-fed larvae may be almost heart-shaped. The basic color is light beige with few dark spots. The dorsal tail fin inserts behind the level of the vent. Both fin sections are of almost equal width and transparent to feebly mottled.
One of the largest tadpole showing no traces of hind limbs measured 18 mm (BL; TL: 52 mm). Much larger tadpoles have been observed. The hind legs are developed at a BL of 18–25 mm and a TL of 50–71 mm. The forelimbs emerge on tadpoles of the same size range. Freshly metamorphosed young measure 24–50 mm (SVL). The following exemplary data are meant to illustrate their development (size in mm / weight in g): 46 / 0.93; 48 / 1.05; 53 / 1.46; 58 / 1.60; 60 / 1.76; 63 / 2.12.
The description of the tadpole published by Lamotte & Zuber-Vogeli (1954a) exactly matches the above given description. These authors give an additional keratodont formula:
4 + 4 // 2+2 / 2. They report on young frogs metamorphosing at a SVL of 29–30 mm.
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