Diagnosis: Small to medium sized frog; very warty skin; no parotid glands; distinct lateral fold; inner metatarsal tubercle very large.
Description: A small to medium-sized compact ranid frog with short legs and a feebly warty skin. SVL 38–51 mm. The tympanum reaches 2/3 of the eye diameter. It is round, but often indistinct. An infratympanic ridge, that might be broken up into separate glands, is present. Eye with oval, horizontal pupil. Marked lateral fold. Finger-tips and toe-tips not enlarged. There is no webbing on the fourth toe up to the second or third phalanx. Tarsal tubercles are usually present. The inner metatarsal tubercle is large and flanged. The outer metatarsal tubercle is either absent or rather small. The ventral skin is smooth. Stewart (1967) and Salvador (1996) give a SVL of up to 64mm.
Coloration: The brownish to beige basic color is either dark mottled or reticulated. A pale vertebral stripe occurs rather often. Pale dorsolateral lines may be present, too. The infratympanic ridge is white. Numerous dark brown, greenish or reddish spots, rather often with black borders, are distributed over head, back and flanks. A light occipital patch occasionally appears on the head. Dark bar markings are found on the upper lip and on the extremities. The venter is light colored, i.e. cream to white. Both sexes have dark bars on the lower jaws. On males, the throat is black as well.
Voice: A short advertisement call with a high frequency is uttered 10–12 times per second (Passmore & Carruthers 1995). Lambiris (1989) describes the advertisement call as a sequence of metallic "chirps" which are repeated very rapidly. Schiøtz (1964c) gives a rapid sequence of low calls lasting 0.3–0.4 sec. DuPreez (1996) describes the advertisement call as a high pitched "KiKiKi". The males call in a chorus and utter approximately 10 calls per second. According to Channing & Bogart (1996), the call characters of T. cryptotis from South Africa are: a call rate of 5–9 calls/sec, with a frequency of 3.1–3.8 kHz, and a note length of 23–48 ms. Passmore (1981a) measured a pressure of 103.5–108 dB at a distance of 50 cm from calling males.
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Angola, Botswana, Cameroon, Chad, Eritrea, Ethiopia, Kenya, Lesotho, Malawi, Mauritania, Mozambique, Namibia, Niger, Nigeria, Senegal, Somalia, South Africa, South Sudan, Sudan, Swaziland, Tanzania, United Republic of, Uganda, Zambia, Zimbabwe
Habitats: Arid habitats such as savannas are preferred (Loveridge 1957, Poynton 1964c, Schiøtz 1963, 1964c, 1967, Lanza 1981, Passmore & Carruthers 1995). The Sahel savanna, habitat of T. cryptotis, receives just 311 mm of rainfall between June and October. In this area, the frogs obviously avoid the river valleys (Forge & Barbault 1978). According to Lambiris (1988), open arid landscapes with sandy soils form the habitat of this species. As far as Zimbabwe is concerned, he mentions not only very arid habitats, but wooded areas, too (Lambiris 1989).
Range: This species has not yet been recorded at Comoé National Park. In particular, records are available for the following countries: Senegal, Nigeria, Niger, Cameroon, Sudan, Ethiopia, Eritrea, Somalia, Uganda, Kenya, Tanzania, Malawi, Zambia, Zimbabwe, Mozambique, South Africa, Botswana, Namibia, Angola (Boettger 1887, Nieden 1915, Loveridge 1925, 1930, 1933, 1957, Scortecci 1929, Parker 1932, 1936b, Angel 1936, Mertens 1955a, b, 1971, Schiøtz 1963, 1964c, 1967, Poynton 1964a, c, Laurent 1965, Perret 1966, Stewart 1967, Broadley 1971, Böhme 1978, Forge & Barbault 1978, Lanza 1978, 1981, Bowker & Bowker 1979, Poynton & Broadley 1985b, Wager 1986, Branch 1988, Lambiris 1988, 1989, Channing 1989, Rödel 1990, Channing & Griffin 1993, Poynton & Haake 1993, Simbotwe & Mubemba 1993, Bates 1995, Passmore & Carruthers 1995, DuPreez 1996, Salvador 1996, Kok et al. 1997, Largen 1997a, 1998). The extreme south-eastern and south-western parts of South Africa remain beyond the range of this species (Passmore & Carruthers 1995).
Life History, Abundance, Activity, and Special Behaviors
Spawn: 2000–3000 pigmented eggs (egg diameter: 1.5 mm, with jelly 3 mm) are deposited individually in shallow, usually rather turbid water. The tadpoles hatch 2–3 days later (Wager 1986, Lambiris 1989, Passmore & Carruthers 1995). Smit (1992) got 966 eggs from a pair.
Tadpoles: The plump, ovoid and somewhat flattened tadpole has a black surface with golden ventral spots. The tail fin is transparent. According to Lambiris (1989), it inserts dorsally at a more craniad position, compared to the animal shown in Wager (1986). The keratodont formula is 1 / 2–2 // 3 (Wager 1986, DuPreez 1996). The lateral papillae form one row up to the corner of the mouth, and two rows thereafter. The mediocaudal section, however, comprises a single row. The beaks are of enormous size and serrated (Wager 1986). The largest tadpole ever collected by Lambiris (1988, 1989) measured 37 mm (TL; BL: 15 mm), whereas Stewart (1967) gives a TL of 39 mm. Parker (1932) gives the keratodont formulae 1 / 2+2 // 1+1 / 2 and 1 / 3+3 // 1+1 / 2. The metamorphosis begins after five weeks (Parker 1932, DuPreez 1996). The young frogs measure about 12 mm (SVL; Stewart 1967, Wager 1986, Lambiris 1989). Burton (1972) gives a period of three weeks until metamorphosis. The tadpoles begin to feed one day after hatching, doubling their weight within two days.
Biology: The frogs spend most of the year buried in the soil. According to Channing & Bogart (1996), Tomopterna species hibernate half a meter or more beneath the soil surface. When disturbed they inflate their body (Salvador 1996). Males call from exposed sites at the banks of streams, pools and puddles. Schiøtz (1964c) writes that they call at least partially from subterranean refuges, too. The frogs spawn in small temporary waters. They are usually nocturnal, but occasionally diurnal during periods of heavy rainfall (Lambiris 1988, 1989, Passmore & Carruthers 1995).
In Transvaal, the breeding season lasts about 150 days. The frogs spawn at night, reacting spontaneously to favorable environmental conditions but stopping their activities with similar promptitude. Rainfall plays a significant role as a trigger of reproductive activity. Kept in captivity, the tadpoles will metamorphose within 29 days. The frogs obviously run considerable risks when they choose a breeding pool quite at random, as mummified tadpoles are found rather frequently (Smit 1992).
According to Lambiris (1989), the diet comprises various arthropods. Loveridge (1933) underlines the importance of termites and beetles. During their fieldwork in Senegal, Forge & Barbault (1978) discovered that almost any potential prey is actually eaten. Lamellicorn beetles, beetle larvae, caterpillars and ants also account for an important part of their diet.
The tadpoles are usually very indolent, lying motionless at the bottom. They form swarms when the waters are in danger of drying up so that more food is whirled up, and thus becomes available (Burton 1972, Lambiris 1989).
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.
Originally submitted by: Marc-Oliver Rödel (first posted 2001-05-02)
Edited by: Vance T. Vredenburg (2002-01-23)
Species Account Citation: AmphibiaWeb 2002 Tomopterna cryptotis: Cryptic sand frog <https://amphibiaweb.org/species/5198> University of California, Berkeley, CA, USA. Accessed Feb 6, 2023.
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Citation: AmphibiaWeb. 2023. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 6 Feb 2023.
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