Description

Beduka tigerina has an elongated, medium-sized body with males having an average snout-vent length of 31.62 +/- 2.06 mm, while females have a slightly larger snout-vent length at around 32.23 +/- 2.41 mm (Biju et al. 2009, Gaitonde et al. 2016). The head is almost equal in both length and width. In the dorsal and ventral view the snout is nearly oval. The snout is longer than the horizontal distance of the eye. The canthal and preorbital ridges are continuous and developed. Beduka tigerina has a vertically acute loreal region. The distance between the anterior margins of the eye is almost half the distance from the posterior margins. The distance between the upper eyelids is less than the width of the upper eye-lid. The tympanum is indistinct, and the supratympanic fold is absent. The parotid glands are present and rounded in shape. The forearm is shorter than the hand, also the prepollex and palmar tubercle are both distinct and rounded. The relative finger lengths are I < II < IV < III. The finger tips are large, rounded, grooveless, webbed, and have lateral dermal fringe. The subarticular and supernumerary tubercles are weakly developed. Nuptial pads are present. The hindlimbs are moderately long with the shank being longer than the thigh. Both the shank and the thigh are shorter than the foot length. The inner metatarsal tubercle is elongated. The relative toe lengths are I < II < III < V < IV. The toe tips are enlarged and rounded and webbing is absent. The subarticular tubercles are indistinct on the toes, with the supernumerary tubercles being less developed. The skin on the snout between the eyes, upper eyelids, side of the head, and back have granular projections with horny spinules. The throat is shagreened to granular and the chest, belly, and posterior side of the thighs are granular as well (Biju et al. 2009).

As of 2021, only two species are in the genus Beduka: B. tigerina and B. koynayensis. Beduka tigerina differs from B. koynayensis by the former having a slightly larger body size, an elongated body, discontinuous canthal and preorbital ridges, stripes on the lateral and dorsal side, and a more yellow body. The lack of webbing between the finger and toes in B. tigerina also differentiate it from B. koyayensis. Additionally, B. tigerinadiffers from B. koynayensis by the former having a denser arrangement of granular projections that have horny spinules on the dorsal and lateral parts of the head, back, and flank. Beduka tigerina has a more prominent canthal and preorbital ridge, as well as a snout that is longer than eye length. Beduka tigerinaalso has a longer shank than thigh, and a foot length that is longer than the shank and thigh when compared to B. koynayensis. Beduka tigerina and B. koynayensis have very similar advertisement calls with a similar peak frequency and structure of pulses. However, the temperature at which the calls were recorded slightly differed; B. tigerinamating calls were recorded at around 24°C, while B. koynayensis was at 19°C (Biju et al. 2009).

In life, during the mating season the dorsum is a golden-yellow color, with the lateral regions being brown with yellow and blue strips extending from the dorsum. During the non-breeding season the dorsum is light brownish grey with yellow lateral stripes. Fingers I and II and toes I and II are whitish. The ventral side is a light grey with random dark greyish brown spots. Lastly, the jaw margins are white in color (Biju et al. 2009).

In preservative, the dorsum, loreal, and tympanic region are a light brown color, with the lateral region being a dark grey with light colored stripes. Fingers I and II and toes I and II are creamy white. The ventral side of the frog is a light brownish gray that has random grey spots all around (Biju et al. 2009).

Beduka tigerina lack distinct sexual dimorphism. However, females are generally larger than males. Individuals exhibit seasonal color changes. During the mating season, both males and females have the same bright yellow dorsum with lateral light yellow and light blue stripes, but after mating season, they both have a light brownish grey dorsum with only light yellow lateral stripes (Biju et al. 2009).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: India

View distribution map in BerkeleyMapper.

Beduka tigerina is found in the tropical evergreen forests in the region of Amboli of the northern Western Ghats of India. The species is endemic and restricted to an altitude of 700 - 1000 m above sea level. The specific habitat of B. tigerina consists of barren-like rocky, lateritic outcrops that lack tree cover during monsoon seasons (Biju et al. 2009, Gaitonde et al. 2016).

Life History, Abundance, Activity, and Special Behaviors

Beduka as a genus has a particularly explosive mating system, specifically during the rainy monsoons seasons, which occur from the months of June to September. They breed on the ground in disturbed patches of evergreen forests. Male Beduka tigerina will cluster near boulders and start a chorus to attract potential females. Males typically started their calls around 1900 hours. Male vocal calls consisted of five notes that were quick and continuous chirps. The first three notes of the vocal call had around two to three pulses, while the final notes were five pulses. Male vocal calls had a peak frequency of around 2844 +/- 172.08 Hz and were found at constant humidity and temperature of 24℃ (Gaitonde et al. 2016).

Female B. tigerina that approach a chorus are quickly mounted by males. With B. tigerina, there is intense competition between males for females as males outnumber females with a 9:1 ratio. These competitions result in “mating balls'', where multiple males try to amplect a single female frog. Many males will fight or dislodge other males off the amplectant pair to get access to the female. Successful males utilize axillary amplexus to grab onto the female at the armpits. Amplexus can last for several hours during which the female carries the male to a suitable oviposition site and lays around two to four large eggs in semi-terrestrial environments, such as vernal pools, small depressions of lateritic rocks, or on wet rocky surfaces (Gaitonde et al. 2016).

After depositing the eggs, the male immediately extends his hind legs and does four to five pelvic thrusts to presumably ejaculate to fertilize the eggs. This thrusting is possibly a result of an adaptation that increases successful fertilization of a small number of single eggs in a semi-aquatic environment and minimizes the gamete and energy required for reproduction. Additionally, thrusts are used as a tactical cue for females, so they know ejaculation has occurred and to continue moving en route to another vernal pool (Gaitonde et al. 2016).

It is theorized that female B. tigerina deposit eggs in several pools to combat the unpredictable cessation of ephemeral pools at the oviposition sites. Females visit an average of four to five pools in a 2-hour period, laying almost seven to eight eggs in each pool. In addition to spreading their eggs across space and time, they also make large investments in egg size (Gaitonde et al. 2016).

Mating females were taken into captivity and laid, on average, 78 single eggs. However, the average total number of ova is around 150 - 180. A single ovary has an average of 59.00 +/- 10.61 ova. Beduka tigerina eggs had a diameter of 3.27 +/- 0.5 mm with a jelly coat and 2.28 +/- 0.3 mm without a jelly coat. The ratio of outer coat to egg is 1.43 mm. The eggs often hatched 3 - 4 days after they were laid (Gaitonde et al. 2016).

The pools, where the tadpoles developed, were around 6.83 +/- 0.48 mm in depth and about 60 - 180 mm wide. The average temperature during larval development was around 25.7℃, with a humidity of around 90 +/- 5%. Beduka tigerina tadpoles are exotrophic and feed on algae around the pools. Tadpoles lived in large densities of 100 - 120. On average, larval duration was short being around 30 - 35 days (Gaitonde et al. 2016).

Mosquito larvae, aquatic beetles, but no other anurans inhabited the same environment as the tadpoles of B. tigerina. No predators were found feeding on B. tigerina eggs or tadpoles, but B. koynayensis had predators, including terrestrial crabs and water scorpions, that prey on their tadpole forms (Gaitonde et al. 2016).

Trends and Threats

Beduka tigerina is abundant locally, but their distribution is severely restricted (Gaitonde et al. 2016). Additionally, B. tigerina faces many threats to their survival due to unpredictable monsoon rains and human development taking place at their habitat (Gaitonde et al. 2016). They are also susceptible to Batrachochytrium dendrobatidis infections (Thorpe et al. 2018).

The climate of the Indian subcontinent and the monsoon seasons are heavily influenced by the fluctuations in the sea-surface temperatures and deficits of rainfall and drought. In recent years, monsoon seasons have halted early leading to the breeding sites for Beduka to dry early and resulting in a high tadpole mortality rate (Gaitonde et al. 2016).

Beduka tigerina’s survival near the rocky outcrops is compromised due to infrastructure development projects, tourism, and changes in land use. The depletion of loose rock due to use for local projects is detrimental to the survival of Beduka. Additionally, the increase in the number of roads nearby may confuse male Beduka as they may choose to set up their chorus to mate there, leading to mass death. Their habitat is rapidly deteriorating because the species lies outside of normally protected areas in India (Gaitonde et al. 2016).

Batrachochytrium dendrobatidis may threaten the already “Critically Endangered” B. tigerina. The pathogen kills many species in the Western Ghats, but B. tigerina showed a low mortality from the pathogen (Thorpe et al. 2018).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Disturbance or death from vehicular traffic
Disease
Climate change, increased UVB or increased sensitivity to it, etc.

Comments

An investigation of the family, Bufonidae, in 2009 using Bayesian Inference, Maximum Likelihood, and Maximum Parsimony on NCX1 and CXCR4 nuclear DNA and 12SrRNA, tRNAVAL, 16SrRNA, tRNALEU, ND1, tRNAILE, tRNAGLN, tRNAMET, ND2 mtDNA found that B. koynayensis and B. tigerina were sister species and were significantly different enough from other members of the family as to warrant the elevation to their own genus (Bocxlaer et al. 2009). This genus was coined Xanthrophryne by Biju et al. (2009) but later changed to Beduka (Dubois et al. 2021). These analyses also showed the Beduka genus is closely related to the genus Duttaphrynus, with “Bufo'' and Duttaphrynus sharing the most recent common ancestor of Bufo melanostictus (Biju et al. 2009).

The genus name, “Beduka”, means "toad" in the Marathi language in Maharashtra, India (Dubois et al. 2021).

The species epithet, “tigerina”, originates from the observed colors and stripe pattern that the frog has and its resemblance to the stripes on a tiger (Biju et al. 2009).

The genus name Xanthrophryne (Biju et al. 2009) was considered to be nomenclaturally unavailable and thus Beduka was proposed as a replacement (Dubois et al. 2021).

The original genus name, "Xanthrophryne" is derived from the Greek word “xanthos” meaning "yellow" and “phryne” meaning "toad" (Biju et al. 2009).

References

Biju, SD, Bocxlaer, IV, Giri, VV, Loader, SP., Bosssuyt, F (2009). "Two new endemic genera and a new species of toad (Anura: Bufonidae) from the Western Ghats of India." BMC Evolutionary Biology, 2, 241-247. [link]

Bocxlaer, Ines Van, Biju, SD, Loader, Simon P., Bosssuyt, Franky (2009). "Toad radiation reveals into-India dispersal as a source of endemism in the Western Ghats–Sri Lanka biodiversity hotspot." BMC Evolutionary Biology, 9, 131-141.

Dubois, A., A. Ohler, and R. A. Pyron (2021). "New concepts and methods for phylogenetic taxonomy and nomenclature in zoology, exemplified by a new ranked cladonomy of recent amphibians (Lissamphibia)." Megataxa, 5, 158-161. [link]

Gaitonde N., Giri, V., Kunte, K. (2016). "‘On the rocks’: Reproductive biology of the endemic toad Xanthophyrne (Anura: Bufonidae) from the Western Ghats, India." Journal of Natural History, 50(39-40), 2557-2572. [link]

Heyer W, De Sa RO, Rettig A (2003). "Sibling species, advertisement calls, and reproductive isolation in frogs of the Leptodactylus pentadactylus species cluster (Amphibia, Leptodactylidae)." Herpetol Petropolitana, [link]

Thorpe CJ, Lewis TR, Fisher MC, Wierzbicki CJ, Kulkarni S, Pryce D, Davies L, Watve A, Knight ME. (2018). "Climate structuring of Batrachochytrium dendrobatidis infection in the threatened amphibians of the northern Western Ghats, India." R. Soc, Volume 5(6). [link]

Species Account Citation: AmphibiaWeb 2021 Beduka tigerina <https://amphibiaweb.org/species/7408> 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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