Comprehensive DescriptionRead full entry
A small ranid frog with a pointed snout. Adult males measure 14–20mm and weigh 0.3–0.8 g. Most of them measure from 17–18 mm and 0.5–0.7 g, respectively. Adult females measure 16–23 mm and weigh 0.4–1.2 g. Most of them measure 19–21 mm and 1.0–1.1 g, respectively. The mean index head width/SVL is 0.26 (s.d. + 0.03; 0.13-0.32; N = 57). No eyelid cornicle. Dorsum and central outer parts of thighs frequently covered with warts which may be quite distinct, particularly on the anterior part of the back. Warts on back usually large and rounded. Additional large comma-shaped warts converging towards the snout are found behind the eyes. However, the skin of the frogs is occasionally altogether smooth. This phenomenon is not a feature of different morphs, but apparently due to different physiological states, as one and the same individual may show both states. Tympanum visible but very small and feebly defined. Males with a subgular vocal sac which is not always clearly discernible. A small inner metatarsal tubercle. An outer metatarsal tubercle is present at the base of the fifth toe. Tarsal tubercle distinct. Webbing formula: 1 (0) or (0.5); 2 i/e (1–0) or (0.75–0.5) or (0.5–0); 3 i/e (1) or (1–0.5); 4 i/e(2) or (1.5); 5 (0.5) or (1). Hands not webbed. The tips of fingers and toes are at most feebly enlarged, but never forming discs.
Voucher specimens:SMNS 8957 1–48 + tadpoles; SMF 78651–56; SMNS 8990 1–2 Ananda, Ivory Coast.
The basic color of the dorsum varies from light gray brown, or darker brown to almost black. Almost black animals are found on darker soil, whereas those encountered on lighter substrates are beige. Breeding males may be bright yellow or green. Parts of the back, especially the warts, may be darker or even black. Dark transverse bands are always present on the thighs and shanks. A fine light mediodorsal line or a broad band, starting just at the snout tip or between the eyes may be present or lacking. These lines or bands may be white, orange, red or green. If they are red they usually show white or orange borders. Very rarely, the lines may be broken, sinus-shaped, zigzagged or ramified. The intensity of the colors apparently depends on the physiological status of the frog, e.g. the backs of breeding males with green dorsal bands may become plain green. However, this color may be "withdrawn" to the center of the back within a few minutes. A dark stripe starting at the snout tip extends above the nostrils to the eyes. Behind the eye, it crosses the tympanum and extends diagonally towards the belly, being occasionally interrupted above the base of the forearm. Another short dark band sometimes stretches from the groin to the back. The lower edges of the posterior thighs bear yellow longitudinal lines with black borders. These lines turn upward in the vent area, fusing occasionally above the anus. The throat and the rest of the venter are usually white; only a few females have throats mottled with black and white. The throats of breeding males are deep yellow. Black points occasionally appear on the throat and in the pectoral area (compare Ahl 1924a). The edge of the lower jaw often bears dark bars. The webs may be slightly pigmented. In alcohol, both the pattern and the warts often fade, so that it becomes difficult to distinguished them from other Phrynobatrachus species. However, the black lateral lines and the vertebral bands and lines usually remain visible, but being less distinct or faded.
The creaking advertisement call starts as a sequence of rapid pulses whose frequency ranges from 2.45–4.82 kHz. This phase lasts about 0.4 sec. After a short pause (0.2 sec), several notes comprising 3–7 pulses are uttered (frequency range: 1.88–5.14 kHz). The duration of a single note ranges from 0.33-0.44 sec, and that of the pauses separating the single pulses is 0.01–0.20 sec; those between the notes last 0.14–0.16 sec. 4–5 click sounds lasting 0.01 sec may precede the call. They are uttered at intervals of 0.23-0.43 sec. Their frequency ranges from 3.11–5.13 kHz. The duration of the longest call recorded was 17.55 sec. However, the call sometimes ends much earlier or even breaks off after the first phase. This happens quite frequently when the frogs call from their refuges during the day in the dry season.
To the human ear, the call of P. accraensis sounds quite similar. Schiøtz (1964c) has published a sonagram which he refers to this species. 3–5 notes, each comprising 1–3 pulses form units which are uttered at short intervals. These calls last up to 7 sec, with up to 35 pulses per second. The frequency intensity maximum lies between 2–4 kHz. Except for its duration, this call shows a structure which resembles, to a large extent, that of the P. latifrons I recorded. Schiøtz (1964c) recorded these calls in a savanna in Sierra Leone.
Böhme et al. (1994) describe the call of P. accraensis as a creaking sound ending with "overturning" clicks. Each sequence consists of 5–7 calls. The call of P. gutturosus is quite similar, but it begins with a long buzzing sound, whereas a few clicks are uttered towards the end.
300 to 1300 eggs are laid as a single surface layer, most frequently attached to vegetation in shallow water zones. The eggs are light sand yellow, and their diameter, incl. the jelly, is 2.2–2.3 mm (egg: 0.8 mm; for P. accraensis, see below).
The basic color of the very tiny tadpoles is dark red-brown. Their body shape is ovoid, and a feeble constriction is discernible on a level with the spiracle. The respective parts show a conspicuous red pigmentation. The tail fin is transparent or finely spotted, starting dorsally on the last quarter of the body and converging evenly towards the tip of the tail. On live animals, the serrated horny beaks seem to be very narrow. If the skin has contracted, e.g. on animals prepared for SEM photos, the beaks appear more voluminous. The keratodont formula is 1 / 1+1 // 2+2 or 1+1 // 2+2. These variations have been recorded within the offspring of a single pair. Additional yet very short and more caudal tooth rows may precede the papillae. All the tooth rows are arranged on the outer edges of dermal folds. The horny teeth have short broad bases. They bear a short semicircular "crown" with 4–5 tips. The mouth is surrounded by a single row of cone-shaped papillae followed by a variable number of filamentous ones. Freshly hatched tadpoles with external gills, do not yet possess oral discs. Their BL is 1.1–1.4 mm (TL: 3.7–4.1 mm). Reared in captivity for two months, they measured 6 mm BL, and 17 mm TL, possessing fully developed hind legs. A few days later, the first young frogs, of approx. 6 mm, left water. Tadpoles captured in ponds and possessing developed hind legs measured 8–10mm. According to my observations, the forelegs emerge at a BL of 7 mm (TL: 12 mm). Six weeks after the beginning of the rains, the first young frogs were observed on the edges of the ponds. They measured 7–7.5 mm, and their coloration was already as variable as in adult frogs.
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