Psammophilus dorsalis (Gray, 1831)

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 : 438-440

Psammophilus dorsalis (Gray, 1831)

( Fig. 8a )

Agama dorsalis –Gray, 1831. In Griffith, E & E. Pidgeon’s Anim. King. ix, 1851: 56

Charasia dorsalis – Gray, 1845. Cat. Liz. Brit. Mus. 1845: 246.

Charasia dorsalis — Boulenger, 1885. Cat. Liz. Brit. Mus. 1845: 450.

Psammophilus dorsalis — Smith, 1935. Fauna of British India, ii, 1935: 209.

Original description. Gray, J. E. 1831. A synopsis of the species of Class Reptilia. In: Griffith, E & E. Pidgeon: The animal kingdom arranged in conformity with its organisation by the Baron Cuvier with additional descriptions of all the species hither named, and of many before noticed [V Whittaker, Treacher and Co., London: 481 + 110 pp. [1830]

Taxonomic comments. Gray (1831) failed to mention which specimens he used to describe P. dorsalis . Currently, there are 20 specimens labelled as P. dorsalis at the Natural History Museum. Boulenger (1885) used eight specimens at NHM to describe Charasia dorsalis collected from Madras, Nilgiris, Malabar and India and labelled these collections as being from Southern India.

There was no precise type locality given in the original description but most of the localities mentioned in older publications suggest collections from different parts of southern India, especially hilly regions ( Boulenger 1890; Smith 1935). The chronological collections of the specimens from NHM need to be verified to choose a lectotype from the specimens at NHM. Since there is very little genetic variation (1–2% in 16S mtDNA) in the samples collected from the Western Ghats of Peninsular India, we provide an expanded description of this species based on the largest male collected during this study and compare with other specimens collected during the study.

Topotypic material. CESL 273, adult male collected from a boulder in grassland in Kotavasal, Achankovil reserve forest, Kerala by SPP and MVP on 28th May 2011.

Other material examined. CESL 326 adult male collected from Kolakumbai, Nilgiri hills, Tamil Nadu ; CESL 0 64 adult female collected from sunrise valley, Wayanad reserve forest, Kerala and CESL 181 adult female collected from near Rishi Valley school, Andhra Pradesh; details of collection locality, specimen voucher and GenBank accession number in Appendix 1.

Diagnosis and comparison. A medium to large sized Psammophilus characterized by the posterodorsal orientation of lateral scales; antehumeral fold well developed; 94–148 midbody scale rows (vs 115–140 in Boulenger, 1885; 115–150 Smith, 1935); ventral scales 112–152; nuchal crest reduced, composed of 15–18 very small, triangular spines, continuous with almost equal to or even smaller dorsal crest which appears like slightly raised denticulation; dorsal crest absent in females and juveniles; two separated, very small supratympanic spines; dorsal and lateral scales keeled, ventral scales strongly keeled; paired postmentals, first pair separated by 1–2 scales; 24–28 subdigital lamellae under fourth finger, 26–34 subdigital lamellae under fourth toe; 11–13 supralabials and 10–12 infralabials; adult males with uniform greyish brown to black body, dorsum lighter; indistinct lighter blotches on the sides, lip scales lighter grey or off-white; females and juveniles with a pair of dorsolateral stripes from neck to above tail, dorsum and lateral speckled with lighter spots.

Morphologically, P. dorsalis is similar to P. blanfordanus , the only other species known from this group, but can be distinguished by a combination of the following characters: 100–140 midbody scale rows (vs 80–100); three samples collected from eastern India close to the type locality of P. blanfordanus also had lower number 84–94 (80–100 Boulenger 1885 & Smith, 1935). Midbody scales row counts clearly overlap with P. dorsalis . Furthermore, all the meristic characters we checked for few specimens overlap (Appendix 3). There is, therefore a need for more thorough examination of morphological and morphometric characters with a larger sample size to diagnose P. dorsalis from P. blanfordanus .

Description. Based on CESL 273, a large sized adult male (SVL- 107.7 mm), morphometric and meristic data are summarised in Appendix 2 & 3. General habitus moderately depressed. Head moderately large (HL/SVL 0.25), not elongated (HW/HL 1.10), maximum width much more than maximum height; snout rounded; rostral broader than high; nostrils in single nasal shield, which is separated from the rostral by two scales; mental shield broader than rostral; two postmentals, first pair separated by two small scales; genials smooth; gular scales keeled, smaller than genials; scales on top of snout feebly keeled towards the edges; scales on top of head heterogenous in size and shape, keeled; supraorbital scales keeled; canthus-rostralis and supraciliary edge sharp; two separated small, triangular spines on posterior end of head, the anterior midway between nuchal crest and tympanum, posterior above tympanum; orbit diameter 65% of distance between anterior border of orbit and snout tip; tympanum exposed, its greatest diameter 39% horizontal diameter of orbit; few slightly enlarged, smooth scales between tympanum and orbit; posterior region of jaws swollen; supralabials 13/13; infralabials 12/12.

Nuchal crest developed, composed of 15 primary, small, triangular spines, the first being the smallest and the eight longest; nuchal crest continuous with a reduced dorsal crest present in the form of elevated serrated ridge, composed of vertebral scales with a more pronounced median keel continuing till above the vent, on the tail in the form of enlarged strongly keeled median scale; 104 longitudinal scale rows around midbody; dorsal and lateral scales keeled, oriented postero-dorsally; ventrals smooth, irregular, as large as the dorsals, slightly larger than the genial and gular scales; an oblique antehumeral fold present, not extending across the throat.

Limbs strong, robust, covered with uniform keeled scales, slightly larger than laterals forming parallel longitudinal rows; scales under thighs weakly keeled; length of hindlimb 71% SVL; relative length of fingers 4>3>2>5>1; relative lengths of toes 4>3>5>2>1; fourth toe slightly smaller than fifth finger; 15 subdigital lamellae under fourth finger; 19 subdigital lamellae under fourth toe; subdigital lamellae with sharp keels, bicarinate; tail thick, gradually tapering, swollen at the base; scales on dorsal and ventral surface of tail with sharp keels, larger than laterals; median scales on the dorsal surface of tail enlarged, with a pronounced median keel; tail length 147 mm (incomplete, broken at the tip).

Colouration. In life: head and body dull blackish-grey with irregular lighter patches near the flank; a longitudinal thick, lighter buff band from behind the head till above the tail; head laterally darker with indistinct reddish brown speckles behind the orbit, a broken reddish stripe from above the nostril till behind the posterior part of orbit covering the supraorbital region; another pale reddish stipe from the nostril till behind the cheek covering the lip scales and lower margin of tympanum; tympanum pale grey; ventral uniformly lighter, pale grey; gular and genial scales lighter, dirty white; tail with a thick lighter band just at the start, then uniform dark grey followed by indistinct lighter bands, bands more prominent towards the tip. In preservative: colouration pattern mostly similar to that in life, except overall paler; bands on lateral side of head distinct.

Variation and secondary sexual characteristics. The other specimens examined agree with the CESL 273 in general morphology and scalation except for some differences that are summarised in Appendix 2 & 3. The examined female specimen (CESL 064) has slightly smaller nuchal spines compared to the males, dorsal crest almost nonexistent; dorsal and lateral scales feebly keeled; tail base not swollen; overall colouration olive-brown, speckled with irregular lighter blotches, 3–4 triangular darker patches on the mid dorsum from neck to the start of tail and series of whitish spots forming broken parallel dorso-lateral stripes.

Distribution. Psammophilus dorsalis is distributed all across the low and medium elevation rocky habitats of central and southern Western Ghats. This species has often been observed on huge rock boulders and sheath rocks in and around forests but seem to be more common in open, drier habitats. During this study, P. dorsalis was recorded in various sites from the southern Western Ghats (See Appendix 1 for details). It is also known from drier habitats throughout peninsular India.

Ecology and natural history. Psammophilus dorsalis is a diurnal lizard, chiefly rupicolous in habit, and so far, has been recorded exclusively in and around rocky habitats. Individuals were mostly observed basking on boulders and rock cliffs in the mornings. In some instances, it has also been observed on isolated rocks inside tea estates and plantations. It is a very shy and active species and escapes inside the gaps and crevices among boulders at the slightest hint of an approaching threat. In the breeding season, the adult males of this species develop a thick bright red to vermilion coloured band from the head extending till behind the lower back and the entire remaining body turns black. Adult males have been observed only during summer and pre-monsoon while gravid females were found in the early monsoon seasons.

Figures

FIGURE 8. Lateral photograph showing live coloration of A. adult male Psammophilus dorsalis and B. adult female Microauris aurantolabium comb. nov.