Monilesaurus rouxii (Duméril & Bibron, 1837 ) Pal & Vijayakumar & Shanker & Jayarajan & Deepak, 2018

Pal, Saunak, Vijayakumar, S. P., Shanker, Kartik, Jayarajan, Aditi & Deepak, V., 2018, A systematic revision of Calotes Cuvier, 1817 (Squamata: Agamidae) from the Western Ghats adds two genera and reveals two new species, Zootaxa 4482 (3), pp. 401-450 : 427-429

Monilesaurus rouxii (Duméril & Bibron, 1837) comb.nov.

Calotes rouxii —Duméril & Bibron, 1837. Erp. Gen, iv, 1837: 407.

Calotes ellioti —(not of Günther) Stoliczka, 1872. J. Asiat. Soc. Beng. (2) xli, 1872: 113.

Calotes rouxii — Smith, 1935. Fauna of British India, ii, 1935: 206.

Syntypes. MNHN—MNHN-RA-0.6894 & MNHN-RA-1994.1857 collected from “ Indes Orientales ” and deposited in the National Museum of Natural History ( France).

Original description. Duméril, A. M. C. and G. Bibron. 1837. Erpétologie Générale ou Histoire Naturelle Complete des Reptiles . Vol. 4. Libr. Encyclopédique Roret, Paris, 570 pp.

Taxonomic comments. The exact type locality of M. rouxii comb.nov. is unknown, as the localities for the syntypes in MNHN and in the original publication are given as “Indes Orientales” or India. The only precise locality of a specimen in the catalogue of British Museum is given as “Matheran, Bombay Presidency” ( Boulenger 1885, 1890); Smith (1935) gives the range of M. rouxii comb. nov. as “Bombay Presidency (Matheran, Khandala, Kanara, Jog); Travancore”. Of these, other than “Travencore” all the other localities are from the northern and central Western Ghats.

Material examined. CESL 129 , adult male collected from Matheran , Maharashtra ; CESL 523 , adult male collected from Brahmagiri Wildlife Sanctuary , Karnataka ; CESL 554 , adult male collected from Pushpagiri Wildlife Sanctuary , Karnataka ; CESL 669 , adult female collected from Bondla Wildlife Sanctuary , Goa ; CESL 834 , adult female collected from Narsimparvata, Kudremukh National Park , Karnataka , CESL 678 , adult male collected from Madhei wildlife sanctuary, Goa ; CESL 875 , juvenile collected from Radhanagri , Maharashtra ; CESL 0 95, juvenile, collected from Agumbe , Karnataka ; 0 72, adult male collected from Wayanad wildlife sanctuary, Kerala ; CESL 123 and CESL 153 adult males collected from Vazhachal , Kerala ; CESL 215 , adult male collected from near Parambikulam wildlife sanctuary, Kerala and CESL 581 , adult male collected from near Pooyamkutty, Kerala. MNHN-RA-0.6894 (photographs only). Details of collection locality, specimen voucher and GenBank accession number in Appendix 1.

Diagnosis and comparisons. A small sized Monilesaurus (SVL up to 74.8 mm) characterized by the posteroventral orientation of lateral scales; antehumeral fold small, triangular spines; two separated small supratympanic spines; dorsal and lateral scales keeled, ventral scales strongly keeled; paired postmentals, first pair in contact or separated by a single scale; 18–21 subdigital lamellae under fourth finger, 24–29 subdigital lamellae under fourth toe; 9–10 supralabials and 8–9 infralabials; olive-brown to above, antehumeral fold black, top of head often darker than dorsum, body often speckled with dark and light blotches, prominent in juveniles and sub-adults.

Morphologically, M. rouxii comb.nov. is superficially similar to M. montanus gen. et sp. nov., M. ellioti comb. nov.; and M. acanthocephalus gen. et sp. nov., but can be distinguished by a combination of the following characters: 52–56 midbody scale rows (vs. 46–52 in M. montanus gen. et sp. nov., 62–64 in M. acanthocephalus gen. et sp. nov., and 52–58 in M. ellioti comb. nov.) spine in the posterior corner of orbit absent (vs. very small, indistinct tubercle like in M. montanus gen. et sp. nov., long, distinct in M. ellioti comb.nov. and much longer in M. acanthocephalus gen. et sp. nov.); 7–8 small nuchal spines (vs. 3–6 small nuchal spines in M. montanus gen. et sp. 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 spines on the back of head and above tympanum (vs. longer, prominent spines in M. ellioti comb. nov. and M. acanthocephalus gen. et sp. nov.) white spot below the eye absent (vs. present in M. ellioti comb.nov. and M. acanthocephalus gen. et sp. nov.; in the form of a band in M. montanus gen. et sp. nov.) and smaller body size: adult SVL 51.4–74.8 mm, n=9 (vs. C. montanus gen. et sp. nov., adult SVL 61–83.4 mm, n=8; and M. acanthocephalus gen. et sp. nov. adult SVL 68.9–72.6 mm, n=3).

Description. Based on CESL 129. A medium sized adult male (SVL- 74.79 mm). Morphometric and meristic data are summarised in Appendix 2 & 3. General habitus moderately compressed. Head moderately large (HL/SVL ratio 0.29), elongate (HW/HL ratio 0.73), 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 in contact with each other; genials keeled; gular scales strongly keeled, 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; two separated spines on posterior end of head, the anterior slightly longer, midway between nuchal crest and tympanum, posterior above tympanum; orbit diameter 75% of distance between anterior border of orbit and snout tip; tympanum exposed, its greatest diameter 58% horizontal diameter of orbit; enlarged keeled scale between tympanum and orbit; posterior region of jaws swollen; supralabials 10/10; infralabials 9/9.

Nuchal crest well developed, composed of eight primary, broadly conical spines, the first and last smaller than the rest; the remaining vertebral scales slightly enlarged relative to adjacent rows and possessing a more pronounced median keel forming a serrated ridge like the dorsal crest which continues till the tail base; 56 longitudinal scale rows around midbody; scales on dorsum keeled, oriented postero-dorsally, while lateral ones oriented postero-ventrally; lateral scales smaller than dorsal, keeled; ventrals strongly keeled, irregular, slightly smaller than dorsals but of similar size as laterals, genials and gular scales; a strong, oblique antehumeral fold, nearly extending across the throat.

Limbs slender and covered with strongly keeled scales, larger than laterals, forming parallel longitudinal rows; scales under thighs weakly keeled; length of hindlimb ca. 82% SVL; relative length of fingers 4>3>2>5>1; relative lengths of toes 4>3>5>2>1; fourth toe longer than fifth finger; 20 subdigital lamellae under fourth finger; 24 subdigital lamellae under fourth toe; subdigital lamellae with sharp keels, bicarinate; tail slender, swollen at the base; scales on dorsal and ventral surface of tail with sharp keels, mucronate, slightly larger than laterals; tail length 118 mm (tail incomplete, broken at the tip).

Colouration. In life: dorsum uniform blackish-brown; head bright reddish-orange, from snout tip to slightly behind mid vertebral; laterally a blackish-brown stripe from above nostril to anterior margin of orbit extending till the tympanum from the posterior margin of orbit in the form of black band; a bright reddish-orange stripe from snout covering labials till the anterior margin of tympanum, continuing backwards from posterior margin and ending abruptly in the antehumeral fold; tympanum pale grey; ventral uniformly black; gular pouch with a small orange stripe in the median row. Representative image showing live colouration ( Fig. 6a ). In preservative: colouration pattern mostly similar to that in life, except overall paler; bands on the head dull greyish brown.

Variation and secondary sexual characteristics. The other specimens examined agree with CESL 129 in general morphology and scalation except for some differences that are summarised in Appendix 2 & 3. Both the examined female specimens (CESL 669 and CESL 834) have much smaller nuchal spines and lack a dorsal crest and gular sac; overall colouration olive-brown, lighter head and vertebral region, a dark band along the side of the head to the neck and the presence of a black antehumeral fold.

Genetic distance. M. rouxii comb. nov. shows 1% intraspecific genetic divergence in the 16S gene; 4–7% interspecific genetic divergence from M. ellioti comb. nov.; 6% genetic divergence from M. acanthocephalus gen. et sp. nov. and 7–8% interspecific genetic divergence from M. montanus gen. et sp. nov. (Appendix. 5).

Distribution. Monilesaurus rouxii comb. nov. is distributed across the low and medium elevation forests (up to 1000 m asl) of the Western Ghats and has also been reported from parts of the southern Eastern Ghats ( Daniels & Ishwar 1994). This is one of the most common forest dwelling agamid lizards in the northern and central Western Ghats. During this study, M. rouxii comb. nov. was recorded in various sites across the Western Ghats (See Fig. 3 & Appendix 1 for details).

Ecology and natural history. Monilesaurus rouxii is a diurnal lizard, semi-arboreal to arboreal in habit, and has so far been recorded mostly in deciduous, secondary and semi-evergreen forests. Individuals were mostly seen perching on branches and actively moving on tree trunks. In some instances, it has also been observed in forest fragments and plantations. In some sites, they occur syntopically in the same habitat as C. versicolor , but tend to prefer higher and thicker perches than C. versicolor , and were found to be more abundant than C. versicolor inside forests. In many instances, gravid females were recorded during pre and mid monsoon (June–August), which suggests that monsoon might be a breeding season for this species.

Figures

FIGURE 3. Map showing distribution of members of Monilesaurus gen. nov. across the Western Ghats, India. Coloured symbols indicate selected sampling localities.

FIGURE 6. Lateral photograph showing live coloration of A. adult male Monilesaurus rouxii comb. nov. and B. adult male Monilesaurus ellioti comb. nov.