Monilesaurus montanus, Pal & Vijayakumar & Shanker & Jayarajan & Deepak, 2018
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publication ID |
https://doi.org/ 10.11646/zootaxa.4482.3.1 |
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publication LSID |
lsid:zoobank.org:pub:10258391-162F-4C7D-AA5E-1A03A4F3FE19 |
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DOI |
https://doi.org/10.5281/zenodo.5996709 |
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persistent identifier |
https://treatment.plazi.org/id/038E021D-FF92-FF82-4FA9-FF0BFA6EFCFC |
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treatment provided by |
Plazi |
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scientific name |
Monilesaurus montanus |
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Monilesaurus montanus gen. et. sp. nov.
( Fig. 7b View FIGURE 7 )
Etymology. The species epithet is derived from the word ‘montane’ referring to the restricted distribution of this species to high elevation forests (> 1500 m a.s.l).
Holotype. BNHS 2411, adult male ( Fig. 13 View FIGURE 13 ), collected at Kudremukh National Park ( Fig. 14 View FIGURE 14 ), Karnataka (1307'54" N, 07516'39" E; 1534.9 m a.s.l); by SPP, SPV and KPD on 28th September 2011.
Paratypes: BNHS 2412, adult male and BNHS 2413, adult female collected from Kudremukh National Park, Karnataka by SPV and ADR on 21st August 2009 ; CESL 131, adult female collected from Siruvani reserve forest, Kerala by SPP and MPV on 0 6th July 2010 ; CESL 133, adult female collected from Walakkad, Silent Valley National Park, Kerala by SPP and MPV on 23rd November 2010 ; CESL 330 adult female and CESL 331 an adult male collected from Naduvattam, Tamil Nadu by SPP on 23rd June 2011 and CESL 529 adult male collected from Narimala, Brahmagiri Wildlife Sanctuary , Karnataka by SPP and SRC on 0 9th March 2012 .
Diagnosis and comparison. A medium sized Monilesaurus with a maximum SVL of 83.4 mm, arboreal species characterized by the backward and downward orientation of lateral body scales; presence of antehumeral fold, throat fold not prominent as the antehumeral fold; 46–52 midbody scale rows; nuchal crest composed of 3–6 small spines; two small separated supratympanic spines; a very small tubercle like postorbital spine barely distinguishable from the surrounding head scales; dorsal and lateral scales feebly keeled, stronger towards ventrals, ventral scales strongly keeled; scales on ventral thigh region feebly keeled; paired postmentals, first pair separated by a single scale; 21–24 subdigital lamellae under fourth finger, 25–30 subdigital lamellae under fourth toe; 9–10 supralabials and 8–9 infralabials; greenish brown above with darker dorsum, a white band below the eye extending till end of jaw.
Monilesaurus montanus gen. et sp. nov. can be distinguished from its sister species based on the combination of following characters: larger body size: adult SVL 61–83.4 mm, n=8 (vs. M. ellioti comb. nov. adult SVL 59.4– 73.8 mm, n=9; M. rouxii comb. nov. adult SVL 51.4–74.8 mm, n=9); lower number of midbody scale rows 46–52 (vs. 62–64 in Monilesaurus acanthocephalus gen. et sp. nov., 52–58 in M. ellioti comb. nov., 52–56 in M. rouxii comb. nov.), presence of a very small, indistinct tubercle like, isolated spine in the posterior corner of orbit (vs. absent in M. rouxii comb. nov., long, distinct isolated spine in M. ellioti comb. nov. and M. acanthocephalus gen. et sp. nov.), 3–6 small nuchal spines (vs. 7–8 small nuchal spines in M. rouxii comb. nov., 6 much longer nuchal spines in C. acanthocephalus gen. et sp. nov., 3–4 long nuchal spines in M. ellioti comb. nov.); small isolated spine on the back of head and above tympanum (vs. longer, prominent spines in M. ellioti comb. nov. and M. acanthocephalus gen. et sp. nov.) presence of white band below the eye (vs. none in M. rouxii comb. nov.; in the form of a spot in M. ellioti comb. nov. and M. acanthocephalus gen. et sp. nov.).
Description of holotype. BNHS 2411, a medium sized agamid, adult male (SVL- 78.2 mm). Morphometric and meristic data are summarised in Appendix 2 & 3. General habitus moderately compressed. Head moderately large (HL/SVL ratio 0.31), broad (HW/HL ratio 0.64), maximum height less than maximum width; snout pointed; rostral broader than high; nostrils in single nasal shield, which is separated from rostral by a single scale; mental shield narrower than rostral; two postmentals; first pair separated from each other by a single, small scale; genials keeled; gular sac small, composed of strongly keeled scales, slightly smaller than genials; scales on top of snout smooth except median row, which is keeled; scales on top of head heterogenous in size and shape, keeled; supraorbital scales keeled; canthus-rostralis and supraciliary edge sharp; a very small tubercle like spine at the posterior corner of the orbit; two separated small spines on posterior end of head, the anterior slightly longer, midway between nuchal crest and tympanum, posterior above tympanum; orbit diameter 59% of distance between anterior border of orbit and snout tip; tympanum exposed, its greatest diameter 48% of horizontal diameter of orbit; slightly keeled, enlarged scales between tympanum and orbit; posterior region of jaws swollen; supralabials 9/9; infralabials 8/8.
Nuchal crest well developed, composed of three primary, conical spines, the first being the shortest, the third longest; the remaining vertebral scales slightly enlarged relative to adjacent rows and possess a median keel forming a slightly elevated ridge like dorsal crest which continues till the tail base; 50 longitudinal scale rows around midbody; 40 scales on the mid dorsum; scales on dorsum feebly keeled, oriented backwards, lateral scales smaller than dorsal, keeled, oriented backwards and downwards; ventrals strongly keeled, irregular, slightly smaller than dorsals but of similar size as laterals, genials and gular scales; an oblique antehumeral fold present, weakly developed, feebly extending into a throat fold which is not prominent.
Limbs slender and covered with strongly keeled scales, larger than laterals, forming parallel longitudinal rows; scales under thighs weakly keeled; length of hindlimb ca. 71% SVL; relative length of fingers 4>3>2>5>1; relative lengths of toes 4>3>5>2>1; fourth toe much longer than fifth finger; 23 subdigital lamellae under fourth finger; 28 subdigital lamellae under fourth toe; subdigital lamellae with sharp keels, bicarinate; slender, swollen at the base; scales on dorsal and ventral surface of tail with sharp keels, mucronate; tail length 190 mm.
Colouration. In life: dorsum and head yellowish-green with irregular, alternating light and dark brown patches on the back; a dark brownish band from above the shoulder till the dorsal crest forming a ‘v’ shape; head laterally greenish with a whitish band below the posterior end of eye to end of jaw; broken dark striations from above nostril to anterior margin of orbit extending till the tympanum from the posterior margin of orbit in the form of black band; tympanum pale green, lip scales white; thick blackish triangular patch behind the tympanum continuing to the antehumeral fold; an indistinct thin stripe above the labials from the nostril, ending into a black spot anterior to the tympanum; ventral uniformly lighter, pale grey; gular pouch white, irregular dark striations on the sides; tail with alternating dark and light blotches forming irregular bands towards the end.
In preservative: dorsum and head buff to light brown with irregular, alternating grey and darker brown patches on the back; tail banded with alternating thick brown and grey blotches; laterally paler with darker brown blotches extending down from the dorsum; lead laterally speckled with grey and brown with a whitish yellow below the posterior end of eye to end of jaw; tympanum pale white, lip scales whitish yellow; ventrally uniform pale grey, lighter below the limbs.
Variation and secondary sexual characteristics. Morphometric and meristic data for the type specimens is presented in Appendix 2 & 3. Adult male paratypes range from 61–78.8mm in SVL, whereas adult female paratypes range from 68.4–83.4mm in SVL. The paratypes agree with the holotype (BNHS 2411) in general morphology and scalation except for the following characters: 46–52 longitudinal scale rows around midbody; 21– 24 subdigital lamellae under fourth finger, 25–30 subdigital lamellae under fourth toe. Supralabials 8 on the right in CESL 124; infralabials 8 on the right in CESL 133 and 8 on the left in CESL 529. All the examined female paratypes (CESL 126, CESL 131, CESL 133 and CESL 331) have slightly smaller nuchal spines compared to the males; lack a dorsal crest and gular sac.
Genetic distance. M. montanus gen. et sp. nov. shows 0–1% intraspecific genetic divergence in the 16S gene; 7–8% interspecific genetic divergence from M. rouxii comb. nov.; 4–8% interspecific genetic divergence from M. ellioti comb. nov. and 2–3 % interspecific genetic divergence from M. acanthocephalus gen. et sp. nov. (Appendix 5).
Distribution. Monilesaurus montanus gen. et sp. nov., is endemic to the Western Ghats and distributed across the high elevation evergreen forests (above 1250 m asl) of central Western Ghats. During this study, M. montanus gen. et sp. nov. was recorded from montane forests of the following hill ranges: Kudremukh, Brahmagiri, Nilgiri and Elivalmalai (See Fig. 3 View FIGURE 3 & Appendix 1 for details).
Ecology and natural history. Monilesaurus montanus gen. et sp. nov., is a diurnal lizard, semi-arboreal to arboreal in habit and so far, has been recorded from montane shola forests ( Fig. 14 View FIGURE 14 ). Individuals were mostly found at night, sleeping on branches of stunted trees within sholas or actively moving on tree trunks. Only in one instance, a female specimen (CESL 133) was found in evergreen forest at a slightly lower elevation (ca. 1250 m asl). In some sites, the lower elevational limits of their distributional range might overlap with the range of M. ellioti comb. nov., but these two species were not observed to be syntopic in any of the sites. A gravid female was recorded in the month of July in Siruvani reserve forest, which hints that pre-monsoon might be a breeding season for this species. No other congeners were found to be syntopically distributed with M. montanus gen. et sp. nov.
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