Ptyctolaemus namdaphaensis, Balan & Das & Boruah & Tillack & Lalronunga & Deepak, 2025

Balan, Amirtha, Das, Abhijit, Boruah, Bitupan, Tillack, Frank, Lalronunga, Samuel & Deepak, Veerappan, 2025, Description of two new species of Ptyctolaemus (Squamata: Agamidae) from northeast India, Vertebrate Zoology 75, pp. 487-516 : 487-516

publication ID	https://doi.org/10.3897/vz.75.e162650
publication LSID	lsid:zoobank.org:pub:FA80C631-51CF-4A23-9BF3-9176C4CEB5D3
DOI	https://doi.org/10.5281/zenodo.17578772
persistent identifier	https://treatment.plazi.org/id/1D82C091-228E-55DE-822E-62DEF5A1020F
treatment provided by	Vertebrate Zoology by Pensoft
scientific name	Ptyctolaemus namdaphaensis
status	sp. nov.

Treatment

Ptyctolaemus namdaphaensis sp. nov.

Figures 14 View Figure 14 , 15 View Figure 15 , 16 View Figure 16 , Tables 3 View Table 3 , 4 View Table 4

Holotype.

WII -ADR 3178 , adult male, from Gandhigram ( 27.26515°N, 96.93878°E, elevation 1135 m a. s. l.), Changlang district, Arunachal Pradesh India, collected on 17 September 2022 by Abhijit Das and Bitupan Boruah. GoogleMaps

Paratype.

an adult female ( WII -ADR 3179 ), collected with the holotype from the same locality as of the holotype by Abhijit Das and Bitupan Boruah GoogleMaps ; an adult female ( ZSI -R-29480 ), collected from Kamala valley , Namdapha TR, Changlang district, Arunachal Pradesh India, collected on 18 May 2022 by Abhijit Das and Bitupan Boruah ; Figure S 3.

Referred specimens.

one adult male ( WII -ADR 1409 ) and three adult females ( WII -ADR 1410 – WII -ADR 1412 ) collected from 18–19 Mile ( 27.48404°N, 96.40473°E, elevation 495 m a. s. l.) on 12 May 2022 by Abhijit Das and Bitupan Boruah GoogleMaps ; one adult male ( WII -ADR 1427 ) from Kamala valley ( 27.45808°N, 96.42804°E, elevation 730 m a. s. l.) on 18 May 2022 by Abhijit Das, Bitupan Boruah and Vijayan Jithin GoogleMaps ; one adult male ( ZSI -R-29481 ) from Kamala valley ( 27.46457°N, 96.43790°E, elevation 540 m a. s. l.) on 3 June 2023 by Abhijit Das, Rajiv N. V., Jason D. Gerard and Sourav Dutta GoogleMaps ; one adult male ( WII -ADR 3061 ) and one adult female ( WII -ADR 3062 ) from 17–19 Mile ( 27.49338°N, 96.39535°E, elevation 450 m a. s. l.) on 8 September 2022 by Abhijit Das, Bitupan Boruah and Naitik G. Patel GoogleMaps ; one adult male ( WII -ADR 1403 ) from 14–15 Mile ( 27.49689°N, 96.35438°E, elevation 430 m a. s. l.) on 9 May 2022 by Abhijit Das and Bitupan Boruah GoogleMaps ; one adult male ( WII -ADR 3283 ) from Haldibari ( 27.52453°N, 96.39913°E, elevation 500 m a. s. l.) on 9 May 2023 by Rajiv N. V. and Sourav Dutta GoogleMaps ; one adult male ( WII -ADR 1440 ) from Motijheel trail ( 27.49624°N, 96.33304°E, elevation 400 m a. s. l.) on 20 May 2022 by Abhijit Das, Bitupan Boruah and Vijayan Jithin GoogleMaps ; one adult female ( WII -ADR 3070 ) from Motijheel ( 27.48644°N, 96.33136°E, elevation 640 m a. s. l.) on 11 September 2022 by Abhijit Das and Bitupan Boruah GoogleMaps . All these localities fall in the Namdapha Tiger Reserve, Changlang district, Arunachal Pradesh, India.

Description of the holotype.

An adult male, SVL 81.22 mm and TAL 123.8 mm (incomplete), with a TAL / SVL ratio 1.52; head distinct from the neck, head longer than wide ( HW / HL = 0.54), slightly concave on top; rostral scale crescent; snout rounded, longer than orbit ( OD / EN = 0.79); scales on loreal region slightly keeled, surrounded by heterogenous scales; nasal separated from rostral by one scale; canthus rostralis sharp with 13 enlarged scales on each side; keels on canthal scales weak towards snout; nostril rounded, in contact with first supralabials; snout scales irregular in shape and size, with inverted Y-shaped pattern at the centre; head height at occipital region 12.89 mm; scales on head, snout and interorbital region heterogeneous; pupil round, horizontal orbital diameter 5.58 mm; tympanum concealed and covered with smooth scales; scales on neck overlapping and small interspersed with enlarged scales, size increases towards the trunk; three enlarged, keeled, and elevated scales behind the orbit; scales around the orbit small and irregular in shape; parietal eye is not distinct; gular distinct; scales on gular heterogeneous in size and mucronate, scales anterior to the gular pouch small, rounded, imbricate, and feebly keeled, larger in the middle; two distinct raised gular folds on either side of midline; folds curved towards midline posteriorly (Fig. 7 View Figure 7 ); eight supralabials on left and nine on right; nine infralabials on both sides; nuchal crest poorly developed, consisting of 21 conical scales (Tables S 4, S 5).

Mental scale triangular, broader than long, and slightly narrower than the rostral; bordered posteriorly by one infralabial on each side, two enlarged postmentals in contact with the first infralabials; postmentals followed by a three small gular scale; four chin shields present on each side, positioned parallel to the infralabials; the anterior portion of the first chin shield contacts the first infralabial, while the remaining part of the first chin shield are separated from the infralabials by one intervening scale row and the other subsequent three chin shields are separated from the infralabials by two intervening scale rows.

Habitus slender, slightly compressed laterally, dorsal scales keeled, imbricate, and posteriorly pointed; mid-dorsal scale row strongly keeled, interspersed with enlarged scale, no enlarged keeled scales on flank; lateral scales heterogeneous, mostly smaller than the dorsals, slightly keeled, imbricate; 104 dorsal scales ( VTSR); 106 rows of scales around the midbody; 126 ventral scales, larger than lateral scales and approximately equal to the enlarged dorsal scales, strongly keeled, imbricate, posteriorly pointed.

Limbs slender, moderate sized, lower arm length slightly longer than upper arm length ( UAL / LAL = 0.91); femur length equal to crus length (femur / crus = 1.01); scales on dorsal surface of forelimbs strongly keeled, uniform and imbricate; scales on ventral side of the forelimbs relatively smaller, feebly keeled; relative length of digits: IV > III > II > V > I; scales on ventral side of hindlimb smaller than dorsal side, slightly keeled and imbricate; relative length of toes: IV > III > V > II > I; 36 / 35 sub digital lamellae under fourth toe, bicarinate.

Tail rounded, slightly compressed laterally, thick at the base, gradually tapering towards tip; covered with homogeneous scales; scales on the dorsal and ventral surface arranged regularly, strongly keeled, and imbricate.

Diagnosis.

A moderate-sized lizard, SVL 45.9–81.2 mm in male (n = 8) and SVL 55.4–72.9 mm in female (n = 7), TAL 115.6–184.5 mm in male (n = 8) and 131.8–181 mm in female (n = 7). Snout scales irregular in shape and size with an inverted Y-shaped pattern. Nuchal crest poorly developed with 12–20 conical scales. Body slightly compressed, scales at the trunk heterogeneous in size, smaller than the dorsal, slightly keeled, oriented backwards, no enlarged keeled scales on flank region, 73–110 dorsal scales ( VTSR), 90–106 rows of scales around midbody, 116–138 ventrals. Mental broader than long, two enlarged postmental in contact with the first infralabials, anterior region of the first chin shield contacts the first infralabial, gular with two distinct raised gular folds on either side of midline, gular scales heterogeneous in size, feebly keeled, scales in middle region larger than those on anterior and posterior region.

Comparison.

Ptyctolaemus namdaphaensis sp. nov. looks similar to P. chindwinensis , as they are sister species. Ptyctolaemus namdaphaensis sp. nov. differs from P. chindwinensis by fewer nuchal crest NC 13–25 (vs. 26–29); P. namdaphaensis sp. nov. can be distinguished from P. collicristatus by relatively larger FLL / SVL 0.50–0.58 (vs. 0.40–0.45), by relatively larger HLL / SVL 0.87–0.99 (vs. 0.64–0.73), by higher number of midbody scales MBS 90–106 (vs. 75–87). Ptyctolaemus namdaphaensis sp. nov. differs from P. gularis by gular region pale-brownish white or bluish white with three broad dark-blue stripes (vs. pale-brown or pale-bluish green or pale-yellowish green; three to four broad dark-blue stripes; Fig. 15 View Figure 15 ). Ptyctolaemus namdaphaensis sp. nov. differs from P. gularis and P. siangensis sp. nov. by absence of enlarged keeled scales on flank (vs. enlarged keeled scales scattered on flank).

In addition, the colouration on the gular region of P. namdaphaensis sp. nov. differs from P. siangensis sp. nov. in having light grass green gular in males (vs. gular with dark blue stripes separated by narrow white lines; Fig. 15 View Figure 15 ). Ptyctolaemus namdaphaensis sp. nov. differs from P. chindwinensis in having a gular with light grass green (vs. bright yellow with two horizontal parallel black stripes). Ptyctolaemus namdaphaensis sp. nov. differs from P. collicristatus in having a gular region yellowish green with black spots (vs. bright yellow medially with greenish-yellow and dark brown laterally).

Morphological variation.

Details of morphometric and meristic variation among the type series are presented in Tables S 4 and S 5. The paratypes ( WII ADR 3179) closely resemble the holotype in overall morphology, with the following distinctions. Each side of the lower jaw bears three chin shields posterior to the postmentals, arranged parallel to the infralabials; a series of six enlarged, keeled scales on the snout form an inverted “ Y ” - shaped pattern, with the first four anterior scales aligned along the midline and pointed posteriorly, posterior to the fourth scale, one scale on either side is oriented diagonally towards the superciliary ridge; paravertebral region rusty brown coloured varied from that of holotype in preservation; nuchal crest composed of enlarged scales in the paratype varied from that of triangular scales in the holotype; the paratype exhibits two enlarged temporal scales that are comparatively smaller than those of the holotype; additionally, the paratype has a moderately distinct gular fold bearing medium-sized, triangular scales, which differ slightly in size and prominence from those observed in the holotype; tail prominent white colouration with distinct brown bands scattered; dark spots on head and reticulation on flank in female paratypes barely visible. Paratype ( ZSI -R-29480 ) shows the following distinctions, a series of six enlarged, keeled scales on the snout form an inverted “ Y ” - shaped pattern, with the first four anterior scales aligned along the midline and pointed posteriorly, posterior to the fourth scale, two scale on either side is oriented diagonally towards the superciliary ridge; paravertebral region rusty brown coloured varied from that of holotype in preservation; the paratype has a moderately distinct gular with medium-sized, triangular scales, which differ slightly in size and prominence from those observed in the holotype; scattered dark brown spots on the mental region is less distinct (Fig. S 3).

Sexual dimorphism.

Adult males have a nuchal crest; gular in males green while the females have pale-yellow gular without any spots (Fig. 16 View Figure 16 ).

Colouration in life.

Head brown or greyish brown or pale-yellowish brown with dark-brown spots; scales with golden yellow keels; pale bands on dorsal surface of head indistinct; dark edged light short streaks radiating from eye; an oblique streak extends from the posterior margin of eye to angle of jaw; lips pale-brown; paravertebral uniform light brown; lateral and dorsal side of neck pale-yellowish brown with irregular dark-brown spots; gular region light grass green with black spots (Fig. 15 D View Figure 15 ); flank pale-yellowish with brown reticulation; reticulation diffused; dorsal surface of limbs brown with pale-yellow and dark-brown spots; tail light brown on the base to reddish brown towards the middle and paler towards tip, dark edged light cross bands and blackish patches irregularly placed; on ventral side, with black spot scattered on the anterior region; mental region creamish yellow with black spot forming irregular line towards the gular.

Colouration in preservative.

Dorsal head light brown with darks tiny spots; light greyish cross band between interorbital region; lateral head light brown with light greyish patch; nostril greyish with tiny black spots; lateral head light brown with greyish patch; enlarged keeled scales on the posterior mandibular region light coloured; few scales on the neck and lateral body with black tips; body light brown to rusty brown coloured; paravertebral region bluish grey coloured; greyish indistinct patch on lateral region; limbs light brown with greyish patch; dark brown patch on the limbs are visible; radial stripes around the eye visible; mantle creamish white with series of black spots forming irregular line; gular region pale bluish coloured; ventral side of forelimb, hindlimb and body creamish with greyish patch, black spots scattered throughout; tail dark brown with indistinct light bands; light bands on the digits visible (Fig. 14 View Figure 14 ).

Sequence divergence.

Ptyctolaemus namdaphaensis sp. nov. has high genetic divergence to its sister species P. chindwinensis 8.2–9.5 %. With other members of the genus, P. siangensis sp. nov. has 8.9–26.7 % genetic difference (Table 5 View Table 5 ).

Etymology.

The specific epithet is a toponym derived from the name of the place “ Namdapha Tiger Reserve ” in the state of Arunachal Pradesh, India.

Common name.

Namdapha green fan-throated lizard.

Natural history and distribution.

We recorded individuals of this species in the following locations: Deban, Motijheel, Gibbon’s Land and Kamala valley in the Namdapha Tiger Reserve (Fig. 11 D View Figure 11 ), and Gandhigram. During the day, we found individuals active along the roadside vegetation and forest trails in May and June of 2022 and 2023. We observed them perching on twigs and ferns at heights of around 1–2 metres above the ground. This species is sympatric with P. gularis in the Namdapha Tiger Reserve. Currently, this species is only known from Gandhigram and the Namdapha Tiger Reserve in Arunachal Pradesh, India.