Species Description: Abraham RK, Mathew JK, Cyriac VP, Zachariah Ar, Raju DV. Zachariah An 2015 A novel third species of the Western Ghats endemic genus Ghatixalus (Anura: Rhacophoridae), with description of its tadpole. Zootaxa 4048: 101-113.
The tadpole description is based off of one tadpole at stage 38. The body is large and depressed. The eyes are moderate sized, directed laterally, and are not visible in ventral view. The nares are an equal distance from the snout and eyes. The spiracle is sinistral and is located at ventrolaterally at the mid body. The tail musculature is well developed. The tail fin is high and pointed at the end with the upper fin being higher than the lower fin. The oval shaped oral disc is located anteroventrally and is laterally emarginated. There are many marginal papillae that frame the oral disc both ventrally and laterally, but they are absent from the upper labium. There are small submarginal papillae that cover the inner rim of the oral disc. The upper jaw is stretched into a wide U-shaped arch, while the lower jaw is V-shaped. The labial tooth row formula is 10(6 -10)/10(10) and helps to differentiate this species (Abraham et al. 2015).
Ghatixalus magnus can be differentiated from other Ghatixalus species of Western Ghats (G. variabilis and G. asterops) by the larger snout-vent length in the focal species; G. variabilis and G. asterops have shorter snout-vent lengths of 46.67 ± 2.0 mm and 41.93 ± 2.0 mm respectively. Additionally, the eye to nostril distance in G. magnus is about the length of the eye diameter, while the eye to nostril distance is shorter than the eye diameter in both G. variabilis and G. asterops. The anterio-ventral surfaces of the thighs in G. magnus are smooth and the posterior sides are areolate, while the full ventral surface of the thighs are areolate in both G. variabilis and G. asterops. Ghatixalus magnus has a larger distance from the tympanum to the eye, and the supratympanic fold extends from the posterior corner of the eye to below the level of the forearm, whereas the fold ends above the level of the forearm in both G. variabilis and G. asterops (Abraham et al. 2015).
The G. magnus tadpole can be differentiated, morphologically, by its large size, coloration and by labial tooth row formulas. Whereas G. magnus has a labial tooth formula of 10(6 -10)/10(10), both G. variabilis and G. asterops have formulas of 7(3 – 7)/6(1). Biologically, G. variabilis and G. asterops are adapted to rocky, montane streams and thus have a moderate oral sucker to help them attach to substrate, whereas G. magnus is found in stream pools within the rainforest during relatively dry months of the year, making it unlikely that the oral appendage is used for adhering to substrates (Abraham et al. 2015).
The coloration of adults in life is a pale rusty-yellow on the dorsal side that has a reticulation of many small, irregular bright-yellow blotches. The lateral side is chocolate brown with cream-colored reticulations and purple-turquoise blotches on the groin. The tympanum and loreal region are pale yellow and a bright-yellow bands runs along the upper part of the tympanic fold down to the canthus rostralis and converges at the snout tip. The iris is a purple-grey color with many black venations. The limbs are rusty-yellow with dark brown cross-bands on the dorsal sides of thigh, forelimbs, and digits. The posterior side of the thigh is brown with randomly scattered yellow blotches. The feet and hands are a light turquoise blue with bluish-brown webbing and yellow disks (Abraham et al. 2015).
The coloration of adult preserved specimens is dark brown with dull-yellow blotches on the dorsal and lateral sides. On the lateral sides the blotches extend from the arms to the groin. The tympanum in a yellow-brown and the upper eyelid is grey. The ventral side is a brownish-grey, with the coloration being lighter at the throat and chest and darker near the posterior end. Lastly, the hands and feet are a pale blue color (Abraham et al. 2015).
The coloration of live tadpoles is yellow-brown with golden iridophores that appear as small spots on the body and as large blotches on the tail. The ventral and ventrolateral sides of the body are a pale yellowish-brown color and less pigmented than the rest of the body. The eyes are golden-brown (Abraham et al. 2015).
Males have a sexual characteristic on their fingers where the nuptial pads on finger III are more pronounced than on finger II (using the Shubin and Alberch  method). Late stage metamorphs and froglets maybe green on the dorsum (Abraham et al. 2015).
Distribution and Habitat
Life History, Abundance, Activity, and Special Behaviors
Ghatixalus is a monophyletic clade that includes G. variabilis, G. asterops, and G. magnus. Based on Maximum-likelihood analysis of 12S, 16S, Rag-1, and RHOD gene sequences, G. magnus forms a strongly supported sister lineage to G. variablis and G. asterops (Abraham et al. 2015).
The species name “magnus” is Latin for “great”. This was chosen, as G. magnus is larger in size compared to other Ghatixalus species (Abraham et al. 2015).
Early descriptions of G. variabilis tadpoles by Annandale (1918) are very likely G. magnus (Abraham et al. 2015).
Tadpoles of the genus Ghatixalus have the greatest number of labial toothrows on both jaws in the family Rhacophoridae (Abraham et al. 2015).
Abraham, R.K., Mathew, J.K., Cyriac, V.P., Zachariah, A., Raju, D.V., Zachariah, A. (2015). ''A novel third species of the Western Ghats endemic genus Ghatixalus (Anura: Rhacophoridae), with description of its tadpole. .'' Zootaxa, 4048(1), 101-113.
Shubin, N.H., Alberch, P. (1986). ''A morphogenetic approach to the origin and basic organization of the tetrapod limb.'' Evolutionary Biology. Plenum Press, New York, 319–387.
Written by Hillary Krumbholz (hkrumbho AT gmail.com), University of California Santa Cruz
First submitted 2016-07-18
Edited by Ann T. Chang (2016-07-28)
Species Account Citation: AmphibiaWeb 2016 Ghatixalus magnus <http://amphibiaweb.org/species/8403> University of California, Berkeley, CA, USA. Accessed Dec 10, 2018.
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Citation: AmphibiaWeb. 2018. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 10 Dec 2018.
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