Description
Raorchestes resplendens is a relatively small frog that was described from five males and two females. The snout-vent length range for males is 22.7 - 24.5 mm and the two females have snout-vent lengths of 25.2 and 28.3 mm. There is a recognizable supratympanic fold extending from the back of the eyes to the beginning of the forelimbs.The skin on the head is smooth whilst the back is rough due to the presence of glandular swellings or macro-glands that are arranged symmetrical along the back and underside. Macro-glands are also located on the sides of the back of the head, on the back side of the vent and the upper sides of both fore- and hind limbs. There is no dorsolateral fold. The fore- and hind limbs are short. No digit webbing is present. The toes have discs with a marginal groove demarcating them. The males have large transparent vocal sacs (Biju et al. 2010).

DIAGNOSIS:

This frog’s distinct red, orange, yellow, and blackish coloration distinguishes it from other Raorchestes. The limbs are also short relative to other members of the genus. This results in a pronounced mode of crawling dissimilar to the other members of Raorchestes (Biju et al. 2010).

COLORATION:

In life, this frog is brightly colored, displaying reds, yellows, oranges, and blackish-browns. The blackish-brown coloration is found along the sides and around the eyes. The back is primarily a deep brick red, with blackish-brown filling the irregularities caused by the macro glands in the skin. The limbs are deep brick red all throughout. The underside is light yellow throughout. This frog has bright red irises. In alcohol, the deep brick red fades to brown, contrasting with the black furrows, and the sides fade to light yellow. The limbs fade from deep brick red to reddish gray, and the underside to yellowish white (Biju et al. 2010).

VARIATION:

No sexual dimorphism is apparent other than females being slightly larger in snout-vent range (Biju et al. 2010).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: India

View distribution map in BerkeleyMapper.

Raorchestes resplendens is endemic to the Munnar-Valparai area of the Anamalai massif of southern Western Ghats, India. This is a mountainous region and biodiversity hotspot on India’s southwestern coast. More specifically, it is restricted to the montane grasslands - consisting of grasslands intermingled with tropical montane forest - also known as shola. The estimated extent of occupancy for R. resplendens is 272 km², mostly within the Eravikulam National Park at 1,896 - 2,695 m elevation. The upper limit, 2,695 m, also represents Anamudi peak where the species was initially found (Das et al. 2020).

Life History, Abundance, Activity, and Special Behaviors
Little is known about the species as it has evaded the scope of researchers for a few notable reasons. They are nocturnal and hide from artificial light sources. Additionally, they are a ground-dwelling species that may retreat into vegetation to avoid detection (Das et al. 2021). Lastly, they are rare. It has been estimated that there are 300 mature individuals in the world, however these values are from data collected prior to the discovery of their expanded range (IUCN 2011).

Raorchestes resplendens has a peak breeding season between May and September (Das et al. 2020). Calling males vocalize at ground level often within layers of vegetation to attract mates (Garg et al. 2021). Due to its expansion, the gular pouch becomes large and transparent when calling (Biju et al. 2010). Males produce a non-pulsatile call differing from those of other bush frogs, as well as pulsatile calls (Das et al. 2020; Garg et al. 2021).

Once a female is attracted to a male’s call, they engage in inguinal and axillary amplexus for fertilization. The female deposits her eggs in burrows at the base of bamboo clumps under moss covering and potentially mate multiple times each season and/or with other mates. There is no parental care; the nest is abandoned by both parties following oviposition (Biju et al. 2010).

Larva

Raorchestes resplendens undergoes direct development, without a free swimming tadpole stage, over the course of 22 - 27 days (Biju et al. 2010).

Trends and Threats
Raorchestes resplendens has an IUCN Red List status of “Critically Endangered” as the species is only known from one, declining population with a fewer than 300 estimated mature individuals. The extent of occurrence for this species is less than 100 km^² and it relies on high altitude grasslands (IUCN 2011). The species occurs in the highly protected Eravikulam National Park, where there are currently no observable threats to this species, and the species has also tested negative for the chytrid fungus, Batrachochytrium dendrobatidis. As such, it is unclear why the species is declining (Biju et. al. 2010, IUCN 2011).

Possible reasons for amphibian decline

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

Comments

PHYLOGENETIC RELATIONSHIPS:

At the time of the species description, Maximum Likelihood and Bayesian Inference analyses of a matrix of mtDNA sequences indicated that R. resplendens was most closely related to the clade compose of R. beddomii and R. munnarensis. The next most closely related species is R. dubois. However, the support for these relationships was low and thus any of these three species could be the sister taxon (Biju et al. 2010). Further Maximum Likelihood and Bayesian Inference analyses on three mtDNA and two nuclear gene fragments indicate that R. resplendens is sister to R. munnarensis. Together they are sister to the clade composed of R. beddomii and R. theuerkaufi, with R. dubois being basal to the group, and rounding out the R. beddomii species complex (Garg et al. 2021).

ETYMOLOGY:

The genus name, “Raorchestes”, is derived from “Rao”, which is in honor of C. R. Narayan Rao, a major contributor to batrachology in India, and “orchestes”, which is a generic term originally used to describe the Philautus genus, a genus nested in the Rhacophoridae family (Biju et al. 2010).

The species epithet, “resplendens”, is Latin and refers to their bright coloration (Biju et al. 2010).

References

Biju, S. D., Shouche, Y., Dubois, A., Dutta, S. K., and Bossuyt, F. (2010). "A ground-dwelling rhacophorid frog from the highest mountain peak of the Western Ghats of India." Current Science, 98(8), 1119-1125. [link]

Das, S., Rajkumar, K.P., Sreejith, K.A., Royaltata, M., Easa, P.S. (2020). “New locality records and call description of the resplendent shrub frog Raorchestes resplendens (Amphibia: Anura: Rhacophoridae) from the Western Ghats, India”. Journal of Threatened Taxa 12(11): 16502–16509. [link]

Garg S., Suyesh R., Das S., Bee M.A., Biju S.D. (2021). “An integrative approach to infer systematic relationships and define species groups in the shrub frog genus Raorchestes, with description of five new species from the Western Ghats, India.” PeerJ 9:e10791 [link]

IUCN SSC Amphibian Specialist Group. (2011). “Raorchestes resplendens.” The IUCN Red List of Threatened Species 2011: e.T189814A8772103. https://dx.doi.org/10.2305/IUCN.UK.2011-1.RLTS.T189814A8772103.en. Accessed in February 2022.

Species Account Citation: AmphibiaWeb 2022 Raorchestes resplendens: Resplendent Shrub Frog <https://amphibiaweb.org/species/7509> 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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