Description
Melanobatrachus indicus is a rare frog with a slender, elongated bodied of uniform width (Beddome 1878). The snout-vent length is reported as up to 28.7 mm in Daltry and Martin (1997), however, the original description states that the body length is 31.75 – 34.92 mm (Beddome 1878) and later summaries on the species state the snout-vent length is 24 – 28 mm (Vitt and Caldwell 2014). The head is wider than long and the short snout length is longer than the eye diameter and the interorbital distance. There is no canthus rostralis or cranial ridges. The pupils are circular and the eye diameter is greater than the distance between the eyes (Daltry and Martin 1997). There is no tympanum or parotid gland. The mouth has a cleft that extends towards the eyelid (Beddome 1878).

The skin on the dorsum of the head and body, and on the hind limbs are covered in tubercles. The arms, flanks, and ventrum are smooth (Beddome 1878, Daltry and Martin 1997).

The fingers are unwebbed and not dilated at the tips. The third finger is twice the length as the other fingers. The fourth finger is short. The hind limbs are about the same length as the snout-vent length with the thigh being shorter than the shank. The cylindrical toes have basal webbing and are undilated at the tips. The fourth toe is much longer than the third (Beddome 1878, Daltry and Martin 1997).

From Duttaphrynus melanostictus, M. indicus can be differentiated by the prominent vertebral ridge in the former that is not found in the latter (Beddome 1878).

In life, the dorsum is black with small white dots. The ventrum sometimes has a few scarlet blotches on the anterior region of chest that can extend to the upper arms and humerus. There are larger white dots on the belly. There is a broad scarlet band across the ventral surface of its thighs near to the groin area that can completely encircle the thighs (Beddome 1878, Daltry and Martin 1997). The aposematic coloration of the belly and limbs remain largely hidden when the species exhibits anti-predator, contraction behavior (Kanagavel & Tapley 2013).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: India

View distribution map in BerkeleyMapper.

Melanobatrachus indicus, the only known species of its genus, is endemic to the Western Ghats of south-western India. The earliest known specimens were found at in the Anaimalai Hills and subsequent specimens were collected from Valparai in the Anaimalais, the Travancore region of Kerala, Vallakadavu Reserve Forest in Kerala State, and in Kalakkad Tiger Reserve in Tamil Nandu State, India (Daltry and Matin 1997). There are only three currently verified sites of this species, which are Kalakad (in the Agasthyamala Hills), Indira Gandhi National Park (in the Anaimalai Hills, Tamil Nadu State), and Periyar Tiger Reserve (in Kerala State). The species is found at an elevational range of 900 – 1,200 m a.s.l. (Biju et al. 2004). Specimens were found under rotting logs, in leaf-litter, under rocks and other moist ground cover near streams in evergreen tropical forests. However, specimens have also been found in degraded tropical forests near primary forests (Daltry and Martin 1997, Biju et al. 2004).

Life History, Abundance, Activity, and Special Behaviors
Melanobatrachus indicus is a rare terrestrial species found in primary and disturbed evergreen to semi-evergreen tropical forests under rotting logs, leaf-litter, rocks, and other moist ground cover within 10 m of streams or in swampy areas (Daltry and Martin 1997, Kanagvel and Tapley 2013). Males can be found calling in pools and streams (Biju et al. 2004). The species breeds in permanent forest streams (Vitt and Caldwell 2014).

When the animal is threatened, it retracts its limbs and arches its back in a form of defensive behavior, known as “contraction”. The main function of this behavior is thought to be to prevent injury during handling and ingestion by predators (Kanagvel and Tapley 2013).

Trends and Threats
The black microhylid frog is an extremely rare species that was rediscovered in 1997 after a long absence. Although the species can be found in protected areas such as Kalakkad-Mudanthurai Tiger Reserve, Indira Gandhi National Park, and Periyar Tiger Reserve, the species is listed as “Endangered” because its it can only be found in an Extent of Occurrence of less than 5,000 km² and that range is severely fragmented and continuing to decline in the extent and quality outside of the protected areas. The causes of habitat decline include the conversion of forested areas to cultivated land (including eucalyptus, coffee, and tea plantations) and the development of dams within the region (Biju et al. 2004).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities

Comments
The species authority is: Beddome, R. H. (1878). “Description of a new Batrachian from southern India, belonging to the family Phryniscidae.” Proc. Zool. Soc. London 1878; 722.

Melanobatrachus indicus is the only known species in the family Melanobatrachinae. Its sister family is Asterophryninae (Vitt and Caldwell 2014).

References

Beddome, R. H. (1878). ''Description of a new batrachian from southern India, belonging to the family Phryniscidae.'' Proc. Zool. Soc. London, 1878(3), 722-723. [link]

Biju, S.D., Vasudevan, K., Bhuddhe, G.D., Dutta, S., Srinivasulu, C., Vijayakumar, S.P. (2004). “Melanobatrachus indicus”. The IUCN Red List of Threatened Species 2004: e.T13032A3406563. http://dx.doi.org/10.2305/IUCN.UK.2004.RLTS.T13032A3406563.en. Downloaded on 02 May 2019.

Daltry, J.C., Martin, G. (1997). ''Rediscovery of the black narrow-mouth frog Melanobatrachus indicus Beddome, 1878.'' Hamadryad , 22, 57-58.

Kanagavel, A., Tapley, B. (2013). ''Defensive behaviour of Melanobatrachus indicus (Anura: Microhylidae) in the Western Ghats, India.'' Herpetology notes, 6, 607-608. [link]

Vitt, L.J., Caldwell, J. P. (2014). Herpetology: An Introductory Biology of Amphibians and Reptiles (4th ed.). Academic Press, Elsevier, San Diego, CA.

Species Account Citation: AmphibiaWeb 2019 Melanobatrachus indicus: Black Microhylid Frog <https://amphibiaweb.org/species/2229> University of California, Berkeley, CA, USA. Accessed Nov 25, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 25 Nov 2024.

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