Description

Diagnosis: Bufo crocus is a moderately-sized (adult males to 59.1 mm SVL, adult females to 67.8 mm SVL), stout-bodied toad. It has a head that is wider than long, protruding snout, subterminal mouth and distinct, cornified cephalic crests (canthal, pre-orbital, and post-orbital). Parietal ridges are weakly defined and are not cornified, in contrast to the other crests. Subarticular tubercles are singular and prominent. Breeding males are bright yellow (Wogan et al. 2003).

Description: The head is wider than it is long, with a protruding snout and a distinct canthus rostralis. Nostrils are rounded and are closer to the snout tip than to the eye. Parotoid glands are prominent and oval-shaped, and are slightly less than twice as long as wide. Pupils are horizontal. Tympanum is vertically oval and small (~2.2 mm diameter) but distinct. No supratympanic fold is present. The tips of fingers and toes are keratinized. Fingers are long, with relative length III>IV>I>II, and lack both webbing and dermal fringes. Fingertips are rounded but not expanded. On fingers, subarticular tubercles are present singly and are prominent and rounded. Hindlimbs have femur and tibia of equal length. Toes are long, with toe IV being half the length of the femur; relative toe length is IV>III>V>II>I. Toes have webbing. No dermal fringe is present on toe V. On toes, the subarticular tubercles are more pronounced than the supernumerary tubercles. The plantar surface of the foot bears numerous tubercles. Inner metatarsal tubercle is round and prominent; outer metatarsal tubercle is also prominent. No tarsal fold is present. Anterior dorsum, anterior snout and region between the eyes all have dense, flat, keratinized warts. Lower lip bears a row of keratinized warts. Posterior dorsum also has flat keratinized warts but less numerous. Flanks have a scattering of flat keratinized warts. Forelimbs, tarsi, and legs also have flat keratinized warts. Venter has flattened glandular warts, with or without spicules. Males possess nuptial spines on the prepollex, first and second fingers (covering the entire dorsal side of finger I), and have proportionately larger forearms than females. Males also have vocal sacs (Wogan et al. 2003).

Coloration in life: Breeding males are bright yellow on the dorsal surfaces of the head, trunk, and limbs, and the lateral surfaces of head and body, with numerous small black keratinized warts clustered around the head and forearms. Non-breeding males are a duller shade of tan. Females are brown with mottled red markings and small black warts. The undersides of both sexes are white with pink. The male holotype has a yellow throat (Wogan et al. 2003).

Similar species: Bufo crocus can be distinguished from the similar species B. melanostictus by its breeding coloration (bright yellow in B. crocus males), smaller body size, in having weak parietal ridges and single subarticular tubercles, and lacking paired warts between the parotoid glands, as well as by calls (a series of notes without distinct pulses in B. crocus, vs. having a variable number of distinct pulses in B. melanostictus) and habitat preference (primary evergreen forest for B. crocus, vs. disturbed habitat for B. melanostictus) (Wogan et al. 2003).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Myanmar

View distribution map in BerkeleyMapper.

Endemic to Myanmar. Bufo crocus has currently only been collected at two localities in primary evergreen forest near the Rakhine Yoma Elephant Sanctuary, Gwa Township, Rakhine Division, on the southwest coast of Myanmar, below 100 m asl (Wogan et al. 2003). The known range of this species will likely be extended by subsequent surveys (Wogan 2004).

Life History, Abundance, Activity, and Special Behaviors
B. crocus is an explosive breeder. Breeding occurs during the earliest rains of the monsoon season, generally late April to early May. Hundreds of individuals gather at night after rains, in pools. Males call in a series of notes without distinct pulses. Outside of the breeding season this species is rarely seen (Wogan et al. 2003).

The marked sexual dichromatism (color difference between sexes) in this species is a rare trait among amphibians, found in only about 30 amphibian species worldwide (Hoffman and Blouin 2000). An interesting, unresolved question is why sexual dichromatism is less common in anurans than in other vertebrates such as birds or lizards.

Trends and Threats
This species is considered Data Deficient. During breeding season it appears to be abundant at the type locality, but is not seen at other times of the year. Regional logging is a threat to this species, which requires primary evergreen forest (Wogan 2004).

Possible reasons for amphibian decline

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

Comments
First described by Wogan et al. (2003). This species has been tentatively placed in the Bufo melanostictus group, given a suite of characteristics shared with B. melanostictus, B. himalayanus, B. cyphosus, B. microtympanum, B. noellerti and B. stuarti.

Etymology: The specific name crocus is Latin for "yellow" or "saffron," a reference to the bright yellow breeding coloration of males (Wogan et al. 2003).

References

Hoffman, E., and Blouin, M. (2000). ''A review of colour and pattern polymorphisms in anurans.'' Biological Journal of the Linnean Society, 70, 633-665.

Wogan, G. (2004). Duttaphrynus crocus. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. www.iucnredlist.org. Downloaded on 07 December 2011.

Wogan, G.O.U., Win, H., Thin, T., Lwin, K.S., Shein, A.K., Kyi, S.W. and Tun, H. (2003). ''A new species of Bufo (Anura: Bufonidae) from Myanmar (Burma), and redescription of the little-known species Bufo stuarti Smith 1929.'' Proceedings of the California Academy of Sciences, 54, 141-153.

Species Account Citation: AmphibiaWeb 2021 Duttaphrynus crocus <https://amphibiaweb.org/species/6415> University of California, Berkeley, CA, USA. Accessed Nov 21, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 21 Nov 2024.

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