Monilesaurus acanthocephalus Pal & Vijayakumar & Shanker & Jayarajan & Deepak 2018
Creators: name: Pal, Saunak
name: Vijayakumar, S. P.
name: Shanker, Kartik
name: Jayarajan, Aditi
name: Deepak, V.
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Reptilia
Squamata
Agamidae
Monilesaurus
Monilesaurus acanthocephalus

description: Monilesaurus acanthocephalus gen. et. sp. nov.
(Fig. 7a)
Etymology. The species epithet is derived by combining the Greek word ‘acanthos’, meaning spine or thorn, and ‘kephale’ latinized as ‘cephalus’ meaning head; referring to the long posterorbital and supratympanic spines.
Holotype. BNHS 2409, an adult male (Fig. 11) collected from a disturbed habitat, adjoining evergreen forest—tea garden edge in Upper Manalar (Fig. 12), Periyar tiger reserve, Megamalai (934'35. 81"N, 7720'11. 43"E; 1562 m a.s.l) by SPV on 8th April 2009.
Paratypes. CESL 0 0 1 adult male and CESL 112 juvenile male collected by SPV on 8th April 2009; BNHS 2410 adult male collected by SPP on 4th September 2011 from Upper Manalar, Periyar tiger reserve, Megamalai (9°34'18. 25"N, 77°20'5. 02"E, 1547 m).
Diagnosis and comparison. A medium sized agamid (SVL = 72.6 mm) characterized by backward and downward orientation of lateral body scales; antehumeral fold present, throat fold present; 62–64 midbody scale rows; nuchal crest composed of 6 long, well developed spines; dorsal crest developed, in the form of a serrated ridge; two long, separated supratympanic spines; a long, well developed postorbital spine; dorsal and lateral scales keeled, ventral scales strongly keeled; paired postmentals, first pair separated by a 1 or 2 scales; 22–24 subdigital lamellae under fourth finger, 27–31 subdigital lamellae under fourth toe; 9 supralabials and 8 infralabials; reddish brown above with alternating dark and light crossbars on the dorsum, two white spots below the eye.
Monilesaurus acanthocephalus gen. et sp. nov. can be can be distinguished from its congeners by a combination of the following characters: 62–64 midbody scale rows (vs. 46–52 in M. montanus gen. et sp. nov., 52–58 in M. ellioti and 52–56 in M. rouxii); presence of much longer, distinct isolated spine in the posterior corner of orbit (vs. absent in M. rouxii; very small, indistinct tubercle like in M. montanus gen. et sp. nov., and smaller in M. ellioti); 6 very long nuchal spines (vs. 3–6 small nuchal spines in M. montanus gen. et sp. nov., 3–4 long nuchal spines in M. ellioti, 7–8 smaller nuchal spines in C. rouxii); longer, prominent isolated spine on the back of head and above tympanum (vs. much smaller in M. montanus gen. et sp. nov., and M. rouxii) and presence of a white spot below the eye (vs. absent in M. rouxii; in the form of a band in M. montanus gen. et sp. nov.).
Description of holotype. BNHS 2409, a medium sized adult male (SVL: 72.6 mm), morphometric and meristic data are summarised in Appendix 2 & 3. General habitus moderately compressed. Head moderately large (HL/SVL ratio: 0.29), broad (HW/HL ratio: 0.65), 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; a long, well developed, thick spine at the posterior corner of the orbit, ca. 54% the orbit in length; two separated spines on posterior end of head, the anterior much longer, between the nuchal crest and tympanum, posterior above tympanum; orbit diameter 56% of distance between anterior border of orbit and snout tip; tympanum exposed, its greatest diameter 49% horizontal diameter of orbit; enlarged keeled scale between tympanum and orbit; posterior region of jaws swollen; supralabials 9/8; infralabials 8/8.
Nuchal crest well developed, composed of six primary, long conical spines, the first being the smallest and the fourth longest; the remaining vertebral scales subtriangular, pointed, much larger than adjacent rows of scales, and possessing a strong, median keel forming an elevated, serrated ridge like the dorsal crest which continues till the tail base; 62 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, extending across the throat.
Limbs long, slender and covered with strongly keeled scales, larger than laterals, forming parallel longitudinal rows; scales under thighs keeled; length of hindlimb ca. 79 % SVL; relative length of fingers 4>3>5>2>1; relative lengths of toes 4>3>5>2>1; fourth toe longer than fifth finger; 22 subdigital lamellae under fourth finger; 27 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 sharply keeled, mucronate, larger than laterals; tail length 215 mm.
Colouration. In life: dorsum olive red with a light brown head, irregular alternating red and black blotches on the mid dorsum, the black blotches extend to the lateral side in the form of alternate ‘v’ shaped bands; 4–5 light green blotches on the lateral side followed by thin whitish stripes from behind shoulder till start of tail; two light broken dorsolateral stripes present; head laterally light olive with three dark black bands from posterior part of eye till tympanum and two white spots below the eye; tympanum off-white with light green edge, lip scales light grey; a large blackish triangular patch behind the tympanum continuing to the antehumeral fold; ventral uniformly white; gular pouch light reddish; tail with alternating spaced dark blotches forming irregular bands towards the end. In preservative: dorsum and head uniform light brown, back banded with five ‘U’ shaped black bands from neck to start of tail; the black bands extend midway laterally forming an alternating pale brown and black pattern; tail banded with alternating thick brown and grey blotches; head laterally pale brown with yellowish white lip scales, tympanum pale grey; ventrally uniform pale whitish yellow with darker blotches below the limbs.
Variation and secondary sexual characteristics. Morphometric and meristic data for the type specimens is presented in Appendix 2 & 3. The adult paratypes are all males and range from 68.9–72 mm in SVL. The paratypes agree with the holotype (CESL 002) in general morphology and scalation except for the following characters: 62– 64 longitudinal scale rows around midbody; 22–24 subdigital lamellae under fourth finger, 27–31 subdigital lamellae under fourth toe; infralabials 9 on the left in CESL 0 0 1 and 9 on the right in CESL 410; 1 st pair separated by a single scale in CESL 410. Dorsal and nuchal crest, spines above the orbit and tympanum not developed in the juvenile paratype CESL 112.
Genetic distance. M. acanthocephalus gen. et sp. nov. shows 4–6% interspecific genetic divergence in the 16S gene from M. rouxii comb. nov.; 5–6 % interspecific genetic divergence from M. ellioti comb. nov. and 2–3 % interspecific genetic divergence from M. montanus gen. et sp. nov. (Appendix 5).
Distribution. Monilesaurus acanthocephalus gen. et sp. nov. is currently known only from high elevations (above 1500 m asl) of Megamalai hills of southern Western Ghats (See Fig. 3 & Appendix 1 for details).
Ecology and natural history. Monilesaurus acanthocephalus gen. et sp. nov. is a diurnal lizard, semiarboreal to arboreal in habit, and has, so far, been recorded from high elevation evergreen forests and along foresttea garden edges (Fig. 12). Individuals were seen perching on shrubs, branches and on tree trunks. One of the type specimens (CESL 410) was found sleeping on a tree branch in a forest patch.
description: Published as part of 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, pp. 401-450 in Zootaxa 4482 (3) on pages 431-434, DOI: 10.11646/zootaxa.4482.3.1, http://zenodo.org/record/1440674