Duttaphrynus crocus (Wogan, Win, Thin, Lwin, Shein, Kyi & Tun 2003)

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

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).

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.

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).

Duttaphrynus crocus, first described in 2003, is a medium-sized toad. Endemic to the Rakhine Division of Myanmar, D. crocus is known only from two closely spaced primary evergreen forest locations near the Gwa township.Survey work around the area have not found additional populations, though Wogan et al. (2003) expect that further surveying will extend the range of this species.

Females reaching a considerably larger size (average snout-vent length 67.7 mm) than males (average svl 56.5 mm).The sexes also have quite different coloration, an unusual sexual dimorphism for amphibians. While males are yellow with black keratinized warts on the dorsal side of the body and legs, females are brown with red and black markings on the dorsal surface.The ventral surfaces of males are mottled white and pink whereas females have darker mottling.This sexual dichromatism is especially pronounced during breeding season.At the beginning of monsoon season (April-May) breeding males turn bright yellow.The reason for this color dimorphism is unclear, but it is suggested that it is not relevant for mate choice (Drewes and Vindum 1994, as cited in Wogan et al. 2003).The male breeding coloration inspires the specific epithet, crocus, Latin for yellow.Breeding D. crocus individuals congregate by the hundreds at small pools, with males calling actively to attract mates.Their call is a series of notes without pulses.Neither eggs nor larvae have yet been observed (Wogan et al. 2003; Wogan 2004).

Except during breeding season, this species is rarely seen (Wogan 2004), and little is known of its ecology.

Upon description D. crocus was placed into the melanostictus group of Bufo. This group was subsequently raised to level of genus, and the new genus name Duttaphrynus applied, breaking up the large genus Bufo (Frost et al. 2006).

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.

Duttaphrynus crocus is a species of toads in the family Bufonidae endemic to the Rakhine State, Myanmar. Its natural habitat is primary evergreen forest. It is threatened by habitat loss (logging).