Description
Sallywalkerana phrynoderma is a medium-sized frog originally described in 1882 from two male specimens with snout-urostyle length of 30.0 and 32.3 mm (Dahanukar et al. 2016 - Leaping). Their snout-vent length range is 9.0 – 47.0 mm and there is no sexual dimorphism (Kanagavel et al. 2018). The head is longer than it is wide. In the dorsal view the snout is sub-oval, in the lateral view it is rounded, and from the profile it protrudes slightly over the wide mouth. The nostrils are located midway between the eye and the snout. The canthus rostralis is indistinct. The loreal region is oblique and slightly concave. The interorbital distance is shorter than the internarial distance. The eye is shorter than the snout length but longer than the tympanum and has a horizontal pupil. The upper eyelid is densely covered in tubercles. The tympanum is indistinct, covered by skin, located approximately half a tympanum length behind the eye (Dahanukar et al. 2016 - Leaping) and approximately 75% of the eye diameter (Kanagavel et al. 2018). A raised supratympanic ridge is visible. Both sub-adults and adults have a characteristic W-shaped ridge of raised tubercles on the dorsum, posterior to the head. The dorsal skin is warty and toad-like, with longitudinal folds along the surface. The lateral sides are granular and the ventrum is smooth (Dahanukar et al. 2016 - Leaping).

The upper arm is shorter than the forearm, and the hand is longer than the forelimb. The outer palmer tubercle is doubled and there are supernumerary tubercles. The fingers have relative lengths of I < II < IV < III and do not have webbing or fringes. The single subarticular tubercles are moderately sized. The fingers end in broad, truncated, moderately sized discs with a semicircular groove that are about 1.5 times the finger width (Dahanukar et al. 2016 - Leaping).

The thigh is shorter than the tibia, and the foot length is longer than the tibia. The inner metatarsal tubercle is thin and elongated and there is no outer metatarsal tubercle. There is a tarsal fold. The toes have relative lengths of I < II < V < III < IV, a toe webbing formula of I 2 – 2 ½ II 2 – 3 III 3 - 4 IV 4 – 2 ¾ V, and there is no outer phalangeal fringe. The subarticular tubercles are moderately sized. The toes have blunt, squared toepads and end in toe discs that are similar in size and appearance to the finger discs (Dahanukar et al. 2016 - Leaping).

Members of the Sallywalkerana genus can be differentiated from Indirana members by the former having less toe webbing. Sallywalkerana phrynoderma is physically similar to S. leptodactyla and S. diplosticta and occurs in sympatry with S. leptodactyla, but the latter two species both have smooth skin and distinct canthus rostralis, whereas S. phrynoderma has warty skin and an indistinct canthus rostralis. The three species can also be differentiated based on their toe webbing formula; where S. phrynoderma has a formula of I 2 - 2 ½ II 2 – 3 III 3 – 4 IV 4 – 2 ¾ V, S. diplosticta has a formula of I 2 - 2 ½ II 2 – 3 III 2 – 4 IV 4 -2 ¼ V in and S. leptodactyla has a formula of I 2 - 2 ½ II 2 – 3 III 3 – 4 IV 4 - 3V (Dahanukar et al. 2016 - Leaping). Sallywalkerana phrynoderma also differs from the more newly described S. muduga, by S. muduga having smooth skin and a distinct canthus. Furthermore, at the time of its description, S. muduga was the only member of Sallywalkerana known from north of the Palghat Gap (Dinesh et al. 2020).

In life, the dorsum is brown to reddish while the ventrum is black patterned with white speckles that are unique to each individual (Kanagavel et al. 2018).

In preservative, the dorsum is brownish to reddish in coloration with a few scattered darker brown spots. The upper and lower mandible are barred by thin, vertical brown stripes. There are also dark bands on the upper eyelids. There is a narrow, indistinct dark brown stripe starting at the tip of the snout and extending through the eye and tympanum to the shoulder. The limbs also have distinct dark brown strips. The sole and foot are dark. The ventrum is cream to pale brown with white speckles and may have a whitish or dark brown W-shaped fold (Dahanukar et al. 2016 - Leaping).

There is no sexual dimorphism. The majority of individuals are dorsally brown, but some individuals are reddish. Individual ventral patterning may vary between a white or dark brown W-shaped folds. Larger individuals have fewer tubercles than smaller individuals (Dahanukar et al. 2016 - Leaping, Kanagavel et al. 2018).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: India

View distribution map in BerkeleyMapper.

Sallywalkerana phrynoderma is strictly endemic to the Anamalai and Cardamom Hills of the Western Ghats in southern India, and specimens of this species are only known from areas nearby or within the Anamalai Tiger Reserve, Eravikulam National Park, Indira Ghandi National Park and Kodaikanal Wildlife Sanctuary in the Palni Hills mountain range. The total geographic range of this species is believed to be less than 100 km² and possibility under 50 km² within these localities (Kanagavel et al. 2018). Sallywalkerana phrynoderma is a high-elevation specialist, restricted to altitudes between 500 - 1750 m within its tropical montane evergreen forested habitat, although it has very rarely been collected from sites below 1300 m (Dahanukar et al. 2016 - Leaping, Kanagavel et al. 2018).

Life History, Abundance, Activity, and Special Behaviors
Sallywalkerana phrynoderma is a nocturnal, secretive, cryptic, terrestrial species about which little is known (Kanagavel et al. 2018). This frog exists at low relative abundance within its habitat and is far rarer than its congener, S. leptodactyla (Biju et al. 2004, Kanagavel et al. 2018).

Sallywalkerana phrynoderma is not active diurnally and spends the day resting camouflaged on shaded forest floors within moss, soil and leaf litter, generally in the vicinity of slow-flowing forest streams. The species has not been found in the water with adults being found further from streams than metamorphs. The areas where the species was found had fewer trees, more saplings, and fewer seedings. The majority of individuals were found at the forests edge rather than in the forest and were associated with soil litter or resting on substrate. More specifically, metamorphs tended to be associated with moss and litter, sub-adults with bare soil and litter, and adults with litter. These differences may reflect shifts in foraging preferences or ability to move in different habitats (Kanagavel et al. 2018).

Although, as of 2018, breeding behavior has not been directly observed, eggs are believed to be terrestrial and to hatch into semi-aquatic tadpoles before metamorphosing into adults. As of 2018, tadpoles have also not been observed (Kanagavel et al. 2018).

The diet and trophic ecology of this species are entirely unknown.

Trends and Threats
Sallywalkerana phrynoderma has an IUCN Red List status of “Critically Endangered.” It is primarily threatened by land use change, habitat loss and fragmentation as a result of subsistence wood collection by humans, as well as pollution in the form of exposure to agriculture runoff and chemical pollutants such as ammonia from nearby tea farming plantations (Biju et al. 2004, Kanagavel et al. 2018).

Sallywalkerana phrynoderma is also known to be a forest-edge specialist, and therefore is likely further threatened by habitat degradation that is intensified by the edge effect (Kanagavel et al. 2018). The high-elevation sites in the tropical evergreen forests, which this frog is restricted to, have been severely fragmented by the development of coffee, tea and cardamom plantations in the Anamalai Hills region (Shankar and Mudappa 2003).

Although chytridiomycosis has been detected in the Western Ghats, as of 2018, the disease has not been detected in S. phrynoderma. Therefore, the effect of the disease on the species is unknown (Kanagavel et al. 2018).

Long term monitoring, assessments on the effects of pollution, and pathogen surveillance are necessary to determine the best management plan for S. phrynoderma. Tourism-induced disturbances, including waste disposal and infrastructure development, should also be evaluated to reduce the impacts of tourism. Sites that are outside of protected areas also need to be monitored as they appear to have similar abundances of the species as inside protected areas (Kanagavel et al. 2018).

Relation to Humans
This species is rarely encountered by humans. It is directly threatened by anthropogenic activities including tourism, agriculture, firewood harvesting and livestock grazing (Kanagavel et al. 2018).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Subtle changes to necessary specialized habitat
Habitat fragmentation
Local pesticides, fertilizers, and pollutants
Long-distance pesticides, toxins, and pollutants

Comments
The species authority is: Boulenger, G. A. (1882). “Catalogue of the Batrachia Salientia s. Ecaudata in the Collection of the British Museum.” Second Edition. London: Taylor and Francis.

Bayesian Inference of 16S rRNA shows that S. phrynoderma is the sister taxon to S. leptodactyla. Their next nearest relative is S. diplosticta followed by S. muduga. The next most closely related genus is Indirana (Dinesh et al. 2020), from which the genus Sallywalkerana was split (Dahanukar et al. 2016 - Leaping).

Species in the genus Sallywalkerana are genetically and morphologically distinct from their descendants as a result of long-term geographic isolation on the Indian peninsula, and the genus itself is thought to have diverged from the rest of Amphibia more than 80 million years ago (Dinesh 2020).

The genus Sallywalkerana is named after Ms. Sally Walker, a renowned zoologist and conservationist, and founder of the Zoo Outreach Organization. Her organization worked to revolutionize and improve zoos across South Asia as well as lobby governments and acquire funding to conserve lesser known, non-charismatic flora and fauna endemic to the Indian peninsular subcontinent. She worked voluntarily as a wildlife and captive conservation champion in India and South Asia for more than 35 years (Dahanukar et al. 2016 - Leaping).

When the genus was first described it was coined, “Walkerana.” It later came to light that a genus of Orthoptera already occupied that name. Thus, this genus was renamed “Sallywalkerana” (Dahanukar et al. 2016 – Sallywalkerana).

References

Biju, S.D., Vijayakumar, S.P., Dutta, S. (2004). “Indirana phrynoderma.” The IUCN Red List of Threatened Species 2004: e.T58314A11763836. https://dx.doi.org/10.2305/IUCN.UK.2004.RLTS.T58314A11763836.en. Downloaded on 13 May 2020.

Dahanukar, N., Modak, N., Krutha, K., Nameer, P.O., Padhye, A.D., Molur, S. (2016). ''Sallywalkerana, a replacement name for Walkerana Dahanukar et al. 2016 (Anura: Ranixalidae).'' Journal of Threatened Taxa, 8(11), 9381–9381. [link]

Dahanukar, N., Modak, N., Krutha, K., Nameer, P.O., Padhye, A.D., Molur, S. (2016). ''Leaping frogs (Anura: Ranixalidae) of the Western Ghats of India: an integrated taxonomic review.'' Journal of Threatened Taxa, 8(10), 9221-9288.

Dinesh, K.P., Vijayakumar, S.P., Ramesh, V., Jayarajan, A., Chandramouli, S.R., Shanker, K. (2020). ''A deeply divergent lineage of Walkerana (Anura: Ranixalidae) from the Western Ghats of Peninsular India.'' Zootaxa, 4729(2), 266–276. [link]

Kanagavel, A., Parvathy, S., Chundakatil, A.P., Dahanukar, N., Tapley, B. (2018). ''Distribution and habitat associations of the Critically Endangered frog Walkerana phrynoderma (Anura: Ranixalidae), with an assessment of potential threats, abundance, and morphology.'' Phyllomedusa , 17(1), 21-37. [link]

Shankar, T.R., Mudappa, D. (2003). ''Bridging the gap: sharing responsibility for ecological restoration and wildlife conservation on private lands in the Western Ghats.'' Social Change, 33, 129-141. [link]

Species Account Citation: AmphibiaWeb 2020 Sallywalkerana phrynoderma: Warty-skinned Leaping Frog <https://amphibiaweb.org/species/4728> University of California, Berkeley, CA, USA. Accessed Jan 1, 2025.

Citation: AmphibiaWeb. 2025. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 1 Jan 2025.

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