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Description
The adult female holotype had a snout-vent length of 26 mm, and a hind limb length of 42 mm (Gunther 1876). The male snout-vent length was 23.7 mm (Seshadri et al. 2015). The obtusely rounded snout of Raorchestes chalazodes is short and about as long as its eye. The canthal ridge is indistinct (Gunther 1876). The head is moderately sized and almost as long as it is broad, with the nostrils being located closer to the tip of the snout than to the eye (Chanda 2002). The eyes are large and protruding. The supra-tympanic fold is barely noticeable (Sivaprasad 2013) and the tympanum is skin-covered. Overall, the skin is smooth, but in the region between the abdomen and thigh, there are several series of white, smooth tubercles. There are also smaller tubercles located in the anal region and along the tarsus. The length of R. chalazodes’s body is equal to its leg length. There is no fold on the tarsus. The metatarsus has a small, mostly indistinct tubercle. The fingers are relatively free, whereas the toes are half-webbed, with large disks (Gunther 1876).

Raorchestes chalzodes has a rounded snout, well-developed supernumerary tubercles on hands and toes, moderate toe webbing that reaches just below the third subarticular tubercle of toe IV on the inside and just past the third subarticular tubercle of toe IV on the outside, which differs from P. beddomii, which has a pointed to nearly oval snout, absent or weakly developed supernumerary tubercles and reduced webbing that reaches up to the second subarticlar tubercle on either side of toe IV. Raorchestes chalazodes also has a foot length (13.1 mm) subequal to its shank (13.3 mm) and thigh length (13.2 mm), whereas P. beddomii’s foot length (9.5 mm) is noticeably shorter than its shank (11.8 mm) and thigh length (11.6 mm) (Biju and Bossuyt 2009). The reproductive mode of R. chalazodes is similar to that of R. ochlandrae. The ‘Palghat Gap’ physically separates the geographic ranges of these species and they nest in different species of bamboo, but morphology and nest characteristics are similar. Both species display parental care and lay their eggs in the upward end of the internode with the entrances being located toward the downward end, presumably to avoid water accumulation from drowning the eggs or froglets (Seshadri et al. 2015).

In life, the dorsal surface appears uniformly greenish, with the exception of the white tubercles. The ventral side of R. chalazodes appears yellowish-white with white tubercles. The femur, on its anterior and posterior surfaces, is yellow with traces of green marbling (Gunther 1876). The eyes in this species have a black pupil connected to a black ring around the margin of the eye, and a yellow iris (Sivaprasad 2013).

In preservative, the specimens of this species become almost uniformly blueish-grey, with slightly more grey ventral sides. Tubercles appear white (Biju and Bossuyt 2009).

Variation has not currently been described.

Distribution and Habitat

Country distribution from AmphibiaWeb's database: India

View distribution map in BerkeleyMapper.

The holotype of Raorchestes chalazodes was originally found in 1875 in Travancore, the southern areas of what is now known as Kerala, a state in the southernmost tip of India, along the Malabar coast (Gunther 1876). The paratypes were all found in the Kalakad Mundanthurai Tiger Reserve which spans from 8.416°N to 8.883°N and 77.166°E to 77.583°E, at an altitude of >1000m above sea level, in the Western Ghats of India, in 2010. This region has two season of heavy rainfall, receiving about 3000 mm per year in total. Most specimens were observed in the native bamboo, Ochlandra travancoria, which grows alongside streams in the primary and secondary forests in the Kakachi and Upper Kodayar areas of the reserve (Seshadri et al. 2015).

Life History, Abundance, Activity, and Special Behaviors
A novel mode of reproduction was observed in R. chalazodes. The polyandrous females of this species lay 5 - 8 direct developing eggs inside a hollow bamboo internode without stagnant water. If amplexus occurs, it must happen within the bamboo internode. Eggs are spherical, 5.73 mm in diameter and transparent, allowing the creamy white yolks to be seen. The ratio of egg yolk to the outer jelly is small. The eggs are laid approximately 25 cm above the opening in the bamboo, and multiple clutches can be found within the same internode. The eggs are attached to the inner wall of the bamboo with a mucilaginous strand. If multiple clutches were present (average of 1.5 clutches per internode), they were separated by gaps of a few millimeters. Each clutch size averages 6.7 eggs. The narrow entry offers considerable resistance, indicating that laying the eggs inside bamboo is a non-random event. For 24 hours after hatching, the froglets remain close to the egg capsules (Seshadri et al. 2015).

The males care for the eggs as they develop until they hatch and can frequently be found vocalizing nocturnally from inside the bamboo and around the narrow entry/exit opening presumably made by insects or rodents. Adult males are found vocalizing between 1800 and 0100h, and this appears to be a method of attracting females (Seshadri et al. 2015). Further Seshadri and Bickford (2018) observed that males are sole caregivers exhibiting egg attendance and egg guarding behavior. Without parental males, predation on unguarded eggs was high, mainly from conspecific cannibalistic males. Competition for oviposition sites is high, especially since conspecific males may benefit from both the nutritional value of the eggs as well as mating opportunities at the oviposition site (Seshadri and Bickford 2018).

Larva
This species is a direct developer (Seshadri et al. 2015).

Trends and Threats
IUCN classifies the species as "Critically Endangered" because it is only known to occur in an area of less than 100 km², and occupies an area of less than 10 km². The distribution of R. chalazodes is severely fragmented and there is a noted decline in the extent and quality of its current habitat (Biju et al. 2004).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Intensified agriculture or grazing
Habitat fragmentation

Comments
The species authority is: Günther, A. (1876). ''Third report on collection of Indian reptiles obtained by British Museum.'' Proceedings of the Zoological Society of London, 567-577.

No phylogeny of the clade including R. chalazodes and R. ochlandrae is currently available, but the similarity of reproductive mode suggests that the two species evolved in parallel or that there is an ancestral linkage (Seshadri et al. 2015).

Raochestes chalazodes has undergone several name changes. When it was discovered in 1875, it was named Ixalus chalazodes by Günther. In 1931, Ahl referred to the species as Rhacophorus (Philautus) chalazodes (Dinesh et al. 2009). In 1985, the species underwent a genus nomenclature change to Philautus (Chanda 2002), before being changed to Raorchestes chalazodes.

The word “chalazodes” is derived from the Greek word for grain “chalaza”, and refers to the white tubercles found on the body of the species (Biju and Bossuyt 2009). It was suggested by Bossuyt and Dubois (2001) that Ixalus chalazodes was synonymous with Ixalus beddomii Günther, 1876, but this has since been disproven by Biju, who identified the species as distinct (Biju et al. 2004; Stuart et al. 2008).

Raorchestes chalazodes was presumed to be extinct shortly after its original discovery in 1875 because it was not found in surveys. However, it was recently rediscovered in 2010, 136 years later, by Ganesan, Seshadri and Biju (Lost Amphibians of India, 2010; Seshadri et al. 2015).

References

Biju, S. D., and Bossuyt, F. (2009). ''Systematics and phylogeny of Philautus Gistel, 1848 (Anura, Rhacophoridae) in the Western Ghats of India, with descriptions of 12 new species.'' Zoological Journal of the Linnean Society, 155, 374-444.

Bossuyt, F., and Dubois, A. (2001). ''A review of the frog genus Philautus Gistel, 1848 (Amphibia, Anura, Ranidae, Rhacophorinae).'' Zeylanica, 6, 1-112.

Chanda, S.K. (2002). Handbook: Indian Amphibians. Zoological Survey of India, Kolkata.

Dinesh, K. P., Radhakrishnan, C., Gururaja, K. V., and Bhatta, G. (2009). ''An annotated checklist of Amphibia of India with some insights into the patterns of species discoveries, distribution and endemism.'' Records of the Zoological Survey of India, Occasional Papers, 302, 1-153.

Günther, A. (1876). ''Third report on collection of Indian reptiles obtained by British Museum.'' Proceedings of the Zoological Society of London, 567-577.

Lost Amphibians of India. (2010). Chalazodes Bubble-Nest Frog: Raorchestes Chalazodes. www.lostspeciesindia.org/LAI2/new1_rediscovered.php. Accessed on 3 November 2016.

S.D. Biju, Sushil Dutta, Karthikeyan Vasudevan, S.P. Vijayakumar, Chelmala Srinivasulu. 2004. Raorchestes chalazodes. The IUCN Red List of Threatened Species 2004: e.T58829A11847257. http://dx.doi.org/10.2305/IUCN.UK.2004.RLTS.T58829A11847257.en. Downloaded on 27 October 2016.

Seshadri KS and Bickford DP (2018). "Faithful fathers and crooked cannibals: the adaptive significance of parental care in the bush frog Raorchestes chalazodes, Western Ghats, India." Behav Ecol Sociobiol, 72(4). [link]

Seshadri, K.S., Gururaja, K.V. and Bickford, D.P. (2015). ''Breeding in Bamboo: a novel anuran reproductive strategy discovered in Rhacophorid frogs of the Western Ghats, India.'' Biological Journal of the Linnean Society, 114, 1-11.

Sivaprasad, P.S (2013). Common Amphibians of Kerala (English). Kerala State Biodiversity Board, Thiruvananthapuram.

Stuart, S., Hoffmann, M., Chanson, J., Cox, N., Berridge, R., Ramani, P., Young, B. (eds) (2008). Threatened Amphibians of the World. Lynx Edicions, IUCN, and Conservation International, Barcelona, Spain; Gland, Switzerland; and Arlington, Virginia, USA.

Species Account Citation: AmphibiaWeb 2022 Raorchestes chalazodes: Chalazodes Bubble Nest Frog <https://amphibiaweb.org/species/4399> University of California, Berkeley, CA, USA. Accessed Apr 18, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 18 Apr 2024.

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