Frogs of Borneo.

Description
Bufo divergens is a small- to medium-sized toad with males ranging from 28-43 mm and females from 36-55 mm (Inger and Stuebing 1997). The head is wider than it is long, and has a pair of continuous supraorbital-parietal crests, usually curved and diverging posteriorly (Inger 1966). Pupils are horizontal, and the iris is golden brown with a dark network (Malkmus et al. 2002). The snout is truncate, usually with a small median bulge at the tip, projecting and oblique in profile (Inger 1966). The tympanum is distinct with a diameter about 3/5 that of the eye (Inger 1966). This toad is generally stocky in shape, with short (Malkmus et al. 2002) but slender limbs (Inger 1966). Dorsal skin has numerous small conical warts, those of sides usually slightly more elevated, and those in the dorso-lateral region usually capped with 3-7 spinules; the ventral skin is coarsely granular (Inger 1966). Parotoid glands are oval-shaped or, more often, triangular, and are separate from the eyelid (Inger 1966); the length of the gland is usually less than three times its width (Inger & Stuebing 1997). An oblique row of enlarged, lateral warts follows the parotoid (Inger 1966). Fingers are moderately long with tips blunt but not swollen; the toes are similarly shaped (Inger 1966). None of the fingers are webbed (Malkmus et al. 2002) and none of the toes are more than half webbed (Inger 1966). The first finger is longer than the second (Inger 1966), and toes in order of length are 4>3>5>2>1 (Malkmus et al. 2002). On the hands, subarticular tubercles are conspicuous but simple; supernumerary metacarpal tubercles are also present (Inger 1966). On the feet, subarticular tubercles are conspicuous and round, and much smaller than metatarsal tubercles. The inner metatarsal tubercles are oval-shaped and shorter than the first toe, and there is a smaller, rounded outer metatarsal tubercle (Inger 1966). There is no tarsal ridge (Inger 1966), but there is a row of spinose tubercles on the inner edge of the tarsus (Malkmus et al. 2002). Males have median subgular vocal sacs with one or two slit-like openings; only 1 out of 20 Bornean males examined for this character had vocal sac openings on both sides of the mouth (Inger 1966). Nuptial pads are a blackish cluster of minute spines covering the dorsal and medial surfaces of the first finger from the base of the finger to the end of the basal phalanx (Inger 1966). 16 out of 34 Bornean males examined had a small oval cluster of nuptial spinules on the medial edge of the second finger as well (Inger 1966). Lineae masculinae are not present in Bornean males (Inger 1966).

Dorsal and lateral coloration is generally clay brown but can range from reddish brown (Inger & Stuebing 1997) to blackish brown (Inger 1966). Ventral coloration is yellow or pale brown and may be immaculate or have dark mottling on the throat and chest (Inger 1966). There may be several isolated black spots or inverted black chevrons on the back; a dark interorbital bar is also usually present (Inger 1966). This is distinctive from B. quadriporcatus, which has no black dorsal markings (Inger 1966). A thin, light vertebral line may be present or absent (Inger 1966). Limbs have dark crossbars (Malkmus et al. 2002). There is no documentation of sexual dimorphism in coloration or patterning, nor of metachrosis.

Tadpoles are 12.4 mm in Stage III (stage 28, Limbaugh and Volpe, 1957; Inger 1966), 15-17 mm in final stages (Inger and Stuebing 1997). The body is oval-shaped and small, and slightly flattened below (Inger 1966). The tail is lanceolate with a rounded tip; the dorsal fin is slightly deeper than the ventral one, and both fins are deeper than the caudal muscle in the distal half of the tail (Inger 1966). The dorsal fin begins over the posterior quarter of body (Inger 1966). Eyes and nostrils are dorsal; the nostrils are much closer to eyes than to the tip of the snout (Inger 1966). The oral disc is ventral and subterminal, about 1/3 maximum body width (Inger 1966). The spiracle is sinistral, just below the line connecting the center of the eye and the root of the hind limb, and is closer to the hind limb than to the eye (Inger 1966). Papillae are short, in a single row confined to the corners of the mouth (Inger 1966); labial teeth rows formula is 2/3 (Malkmus et al. 2002). 28 teeth counted; rows of upper lip are equal and longer than rows of lower lip, which are subequal; beaks are smooth and narrowly edged with black (Inger 1966). Bufo divergens tadpoles do not have expanded lips like tadpoles of B. asper and B. juxtasper (Inger and Stuebing 1997).

Dorsal tadpole coloration is dark gray or brown (Inger 1966) to black (Malkmus et al. 2002), whitish or unpigmented ventrally (Malkmus et al. 2002). The caudal muscle is gray and lighter below; the dorsal fin is also gray, but with dense melanophores; the ventral fin is gray with only a band of melanophores along its base (Inger 1966).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Indonesia, Malaysia

Malaysian region distribution from AmphibiaWeb's database: Sabah, Sarawak

	View distribution map in BerkeleyMapper.
	View Bd and Bsal data (2 records).

Bufo divergens is found in Eastern Sumatra, throughout Borneo, and on the Natuna Islands (Inger 1966). It is a toad of forest floor leaf litter and occurs in primary and old secondary forest below 700 m a.s.l. (Inger and Stuebing 1997) to 1000 m (Malkmus et al. 2002). It has also been observed on plantations and in village clearings (Inger 1966). It is commonly found near very shallow, small streams (Inger and Stuebing 1997) or around the edges of small rain-filled pools, especially during the breeding season (Inger 1966).

Life History, Abundance, Activity, and Special Behaviors
Bufo divergens is mainly active at night, although it has also been observed hunting (Malkmus et al. 2002) or hopping on the forest floor by day (Inger 1966). It spends most of its time amidst the forest floor leaf litter and near very shallow, small streams or in rain pools on the forest floor (Inger and Stuebing 1997). Males were observed calling at night around the edges of small rain-filled pools in April, May, August, and September. Males call with a series of short (Malkmus et al. 2002), querulous, raspy, rising trills (Inger and Stuebing 1997). Males usually form noisy calling groups (Inger & Stuebing 1997) along the edges of spawning sites (Malkmus et al. 2002). This species mates in axillary amplexus (Malkmus et al. 2002).

Females with enlarged pigmented ova were caught in May, June, and July (Inger 1966). Females lay egg strings with numerous, pigmented ova in stagnant or slowly flowing water. Larvae are of a generalized type, with spheroidal bodies, keratinized beaks, and deep fins (Malkmus et al. 2002). Tadpoles occur in the shallow areas of stagnant or slowly flowing water in small streams (Malkmus et al. 2002). Usually tadpoles from eggs laid in small streams are found where the current is weakest (Inger and Stuebing 1997). The tadpoles are bottom suspension feeders (Malkmus et al. 2002).

Adults feed on a wide variety of arthropods, favoring ants and termites (Malkmus et al. 2002).

This species appears to occur everywhere in well-drained lowland rainforest, but is not considered to be an abundant species (IUCN 2006).

Trends and Threats
Populations of this species are declining, though for unclear reasons (Voris and Inger 1995). Threats include habitat loss due to clearcutting of forests. This is occurring at an increasing pace in both Borneo and Sumatra (IUCN 2006).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities

Comments
This species was originally given the name Bufo divergens (Peters 1871), though Boulenger (1882) called it Bufo biporcatus. Inger refers to it as Bufo biporcatus biporcatus in Inger (1954) and Bufo biporcatus divergens in Inger (1966). It was known under the name Bufo divergens until Frost et al. (2006) renamed it under the genus Ingerophrynus. The name Ingerophrynus derives from a combination of the surname of Robert F. Inger, commemorating his achievements in herpetology of the Malay Peninsula, Indonesia, and Borneo, and the Greek -phrynos which means "toad" (Frost et al. 2006).

References

Frost, D. R., Grant, T., Faivovich, J., Bain, R. H., Haas, A., Haddad, C. F. B., de Sá, R. O., Channing, A., Wilkinson, M., Donnellan, S. C., Raxworthy, C. J., Campbell, J. A., Blotto, B. L., Moler, P., Drewes, R. C., Nussbaum, R. A., Lynch, J. D., Green D. M., Wheeler, W. C. (2006). "The amphibian tree of life." Bulletin of the American Museum of Natural History, 297, 1-370. [link]

IUCN, Conservation International, and NatureServe. 2006. Global Amphibian Assessment: Bufo divergens. www.globalamphibians.org. Accessed on 14 May 2008.

Inger, R. F. (1966). ''The systematics and zoogeography of the Amphibia of Borneo.'' Fieldiana Zoology, 52, 1-402.

Inger, R. F., and Stuebing, R. B. (1997). A Field Guide to the Frogs of Borneo. Natural History Publications (Borneo) Limited, Kota Kinabalu.

Malkmus, R., Manthey, U., Vogel, G., Hoffmann, P., and Kosuch, J. (2002). Amphibians and Reptiles of Mount Kinabalu (North Borneo). Koeltz Scientific Books, Koenigstein, Germany.

Voris, H. K. and Inger, R. F. (1995). ''Frog abundance along streams in Bornean forests.'' Conservation Biology, 9(3), 679-683.

Species Account Citation: AmphibiaWeb 2014 Ingerophrynus divergens: Crested Toad <https://amphibiaweb.org/species/6003> University of California, Berkeley, CA, USA. Accessed Nov 12, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 12 Nov 2024.

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