Diagnosis: Medium sized plump frog; typical Y-shaped pattern on throat; characteristic dorsal pattern.
Description: A plump, medium sized ranid with a blunt snout. The one adult female ever collected in Comoé National Park measured 38 mm (SVL). A male reared in captivity reached 67.1 mm SVL. Males have paired lateral vocal sacs whose slits are situated immediately anterior to the armpit. When inflated, they almost touch each other in front of the snout (Amiet 1974b). The large tympanum is set apart from the eye and is barely visible on young animals, but conspicuous on adults. It equals 0.5–0.6 of the eye diameter. Comparatively short hind limbs. Both thigh and lower leg reach just half of the SVL. The short hands reach 0.2 of the SVL. The inner metatarsal tubercle reaches at least more than 0.5 of the shortest toe length, or even surpasses its length. Webbing formula: 1 (1), 2 i/e (1–0.5), 3 i/e (2–1), 4 i/e (2.5), 5 (1).
Poynton (1964a) and Lambiris (1989) give a maximal length of 65 mm. Lambiris (1980) even gives 70 mm (SVL). Boulenger (1907a) mentions 48 mm. Schmidt & Inger (1959) describe nuptial pads developing on the first three digits, including their bases, of male H. ornata moeruensis (see below).
Voucher specimens:SMNS 8948 1–10 + tadpoles.
Coloration: A broad green vertebral band runs from the snout tip to the end of the body. It either covers all of the snout or, in most specimens, it is split up immediately into three separate stripes. In this case, the median one will continue to the end of the body. Like the remaining green parts, it tends to be replaced on adult frogs by clear brown colors, that expand from the flanks. The two lateral green lines run from the outer border of the eyelids to the end of the body. Even on young individuals, they tend to be fragmented, forming various dots and strokes. Wherever the green colors fade, they are replaced by brown ones. The space between those at least partially green lines is occupied by two parallel brown lines. Some young have a back which is completely green. The basal section of the eyelid is pale to dark brown; in the former case, it often bears dark brown spots with black borders.
A narrow white stripe begins at the snout tip, i.e. below the green lateral stripe, crossing the eye at a level superior to the pupil and fading out somewhere behind the eye. This stripe is ventrally accompanied by a small dark brown triangle with black borders which stretches from the snout tip to the shoulder. In the caudal section of this triangle, however, only the borders and the tympanum keep their dark coloration, the remaining parts of the skin being rather dark gray. The tympanum partially shows a narrow white border. The upper lip is white up to the armpits. In the sector preceding the eye, a short green stripe occasionally appears. A broad pale to dark red line starts at the posterior border of the eye, i.e. above the dark zone surrounding the tympanum, running obliquely towards the groin. A rather short extension of this line starts above the armpits, bending back first towards the latter and finally pointing down perpendicularly. This extension also crosses the temporal triangle which runs to the belly where it becomes gray, bearing numerous black to dark brown spots and strokes. The diagonal red brown and the greenish dorsolateral lines enclose a triangle pointing towards the head. This area shows a dark brown color, especially on young frogs, whereas adult individuals have only continuous dark borders and a number of dark patches left. The rest of the triangle turning gradually rather pale.
The shoulder also bears a dark triangle, and the rest of the upper arm is beige to flesh-colored. Two elongate dark brown triangles pointing towards the hands appear on the lower arms. The hind limbs bear dark brown lines, two on the thigh, three on the lower leg. The outer parts of the thighs are mottled. The proximal parts of the lower legs often show green intervals separating the above-mentioned bars. The foot is clear brown with four to five dark transverse bars.
The throat bears two more or less symmetrical y-shaped white markings whose short branch point towards the corners of the mouth. Individuals from the Comoé National Park usually lack the shorter branch of the Y. The white markings are usually framed by dark brown to black bands. The remaining skin areas are paler brown, with the exception of the jaw borders and of the corners of the mouth which are both dark. The venter is whitish. The pectoral region and the flanks may be brown, too. The vocal sacs of the males are slate gray. In alcohol the green colors completely fade, turning red-brown. Some brown areas may turn red or reddish. Many markings either fade or disappear, being replaced at worst by a uniform dark brown. In this case, the frogs can only be identified by means of their throat markings; however, most individuals still show faint traces of the general markings.
Voice: At Comoé National Park, the advertisement call has been heard only occasionally. A male uttered squawking release calls when gripped at the inguinal region. Amiet (1974b) describes the advertisement call as a very low sonorous "hôn" which is uttered slowly and at very regular intervals over a long period. Each call lasts about 0.2 to 0.3 sec. Passmore & Carruthers (1995) report on a long nasal "quack" lasting 0.4 sec at a frequency of 0.4–0.6 kHz. According to Lambiris (1989), the low frequent call, "quack", lasts 0.5 sec, being repeated every two seconds.
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Angola, Benin, Botswana, Cameroon, Central African Republic, Congo, the Democratic Republic of the, Cote d'Ivoire, Gambia, Ghana, Kenya, Malawi, Mali, Mozambique, Namibia, Nigeria, Senegal, Somalia, South Africa, Swaziland, Tanzania, United Republic of, Togo, Uganda, Zambia, Zimbabwe
Habitats: Up to now, I have found tadpoles exclusively in savanna ponds. However, the one adult specimen ever collected in the national park was captured in a gallery forest. In Ghana, the species inhabits the Sudan savanna (Loveridge 1955b, Hughes 1988). All over its range, it apparently prefers rather dry and open landscapes (e.g. Urban 1969, Lambiris 1988, Amiet 1989/90, Passmore & Carruthers 1995).
Range: Presumably distributed over all savanna regions south of the Sahara, stretching to southern Africa. However, the species is encountered very rarely. In particular, they have been recorded in the following countries: Senegal, Gambia, Mali, Ivory Coast, Ghana, Togo, Cameroon, R.D. Congo, Central African Republic, Somalia, Ethiopia, Kenya, Tanzania, Malawi, Zambia, Zimbabwe, Mozambique, South Africa, Namibia, Angola (Peters 1878, Boulenger 1919a, b, Nieden 1915, Noble 1924, Loveridge 1925, 1930, 1955b, c, 1957, Witte 1934, Mertens 1955b, 1971, Schmidt & Inger 1959, Poynton 1964a, c, 1991, Stewart 1967, Urban 1967, Broadley 1971, Amiet 1973a, 1974b, 1989, 1989/90, Stevens 1974, Miles et al. 1978, Bowker & Bowker 1979, Lamotte & Xavier 1981, Poynton & Broadley 1985b, Schätti 1986, Wager 1986, Branch 1988, Hughes 1988, Lambiris 1989, Joger 1990, Channing & Griffin 1993, Poynton & Haacke 1993, Simbotwe & Mubemba 1993, Passmore & Carruthers 1995, Rödel 1996, 1998b, Joger & Lambert 1997).
Life History, Abundance, Activity, and Special Behaviors
Spawn: Unknown at Comoé National Park. The eye diameter is said to be 1.4 mm without and 3 mm with jelly. Single eggs are deposited in shallow water (Wager 1986, Lambiris 1989), often being scattered over a considerable area (Passmore & Carruthers 1995).
Tadpoles: Large, very muscular animals with compact, almost rectangular bodies and long tails. The base of the tail axis particularly muscular. The dorsal section of the tail fin begins at the level of the vent and shows a slightly convex border, whereas that of the ventral section is more or less straight. Tail fin occasionally with a tail filament. The fin is translucent clear or mottled with dark. The eyes are positioned laterally. The thick upper lip is clearly visible from above. Depending on the respective substrate, the tadpoles are either beige, dark brown or olive. A marked green metallic basic coloration is usually discernible, and this metallic glimmer can be considered as a feature which distinguishes these tadpoles from those of any other species.
The keratodont formula is 0 // 2. The upper horny jaw is slender and slightly convex at the center, the lower one very sturdy, showing two prominent "teeth". The jaws are not serrated and are lined by thick lips. The latter are lined laterally and caudally by a single row of small papillae. Those papillae at the corners of the mouth are the largest. The horny teeth are located in skin depressions; each has one single point, and the ratio width / length is 1/1.7 – 1/3.2, depending on the respective position. The blunter teeth are usually arranged at the end of a row.
So far, no freshly hatched tadpoles have been found. The smallest tadpole ever collected measured 8 mm. However, the tadpoles apparently grow quite rapidly. In 1994, I found a larva measuring 20 mm in a pool which had developed after heavy rainfall just four days before. Three weeks after the start of the rainy period, we already found tadpoles which were about to metamorphose. At this stage, the BL was 16–20 mm (TL: 43–53 mm). Animals with fully developed hind limbs measured 17–20mm (BL; TL: 51–62 mm). The longest larva whose hind limbs were just emerging measured 56 mm. The length of freshly metamorphosed young frogs was 20–21 mm.
Lambiris (1989) shows a larva which resembles the animals found in the Comoé National Park. Showing an identical oral disc with enlarged anterior papillae, they have higher backs and are altogether more rounded. Lambiris (1989) gives a maximal TL of 88 mm (BL:
29 mm). He does not mention any metallic glimmer. The drawing in Wager (1986) is even more similar to the Comoé tadpoles, but it does not show any enlarged papillae on the oral disc. According to Wager (1986), these rather fat tadpoles even achieve a TL of 95 mm (BL: 25 mm). The end of the elongate tail fin is lash like.
Biology: Collected tadpoles demonstrate that the reproductive activities of H. ornata starts immediately when the rainy season sets in, i.e. when the larger savanna waters are filled with water. Although known spawning sites were controlled at those nights, I never encountered adult frogs. Later visits undertaken both during periods with and without rainfall proved to be unsuccessful, too. We never succeeded in locating single calling specimens. Most probably, they were calling in subterranean refuges. The only one adult animal collected so far was sitting during the day in the center of a sunny part of the forest floor. Although this forest, which is situated in the vicinity of a very important breeding pond, was thoroughly searched, no further frogs were found. As far as that goes, the life history of adult frogs in Comoé National Park is still unknown.
In the southern part of the national park, the tadpoles develop in a few large waters harboring little or no vegetation. Within these habitats they prefer the deepest parts. In the center of the park I found tadpoles in a heavily overgrown shallow pond, too. Younger larvae were repeatedly found during the rainy season, developing into frogs within a few weeks. The young will spend some time near the pond if there are sufficient humid refuges below stones and dead wood.
Aquarium experiments have demonstrated that the larvae of H. ornata are carnivorous, preying successfully on other tadpoles. This behavior is confirmed by Lambiris (1989). They presumably devour their siblings, too (Lambiris 1989). It is not known whether this cannibalistic behavior is a laboratory artifact or not. Noble (1924) reports that adult H. ornata feed on young toads and arthropods.
Amiet (1974b, 1989/90) describes a very short breeding season in the early rainy period in Cameroon. H. ornata apparently spends most of the year underground (Amiet 1974b, Passmore & Carruthers 1995). Males are reported to call at the pond edge (Lambiris 1988). According to Channing & Griffin (1993), males call from the water in shallow pans and flooded areas. They call fairly late in the evening. The spawning sites include various types of very small ponds (Urban 1967, Lambiris 1988, Passmore & Carruthers 1995) and inundated meadows (Poynton & Haacke 1993).
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 Vance Vredenburg (2002-01-14)
Species Account Citation: AmphibiaWeb 2002 Hildebrandtia ornata: Ornate frog <http://amphibiaweb.org/species/4708> University of California, Berkeley, CA, USA. Accessed Oct 19, 2017.
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Citation: AmphibiaWeb. 2017. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 19 Oct 2017.
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