Ptyctolaemus chindwinensis, Liu & Hou & Lwin & Rao, 2021

Liu, Shuo, Hou, Mian, Lwin, Ye Htet & Rao, Dingqi, 2021, A new species of the genus Ptyctolaemus Peters, 1864 (Squamata, Agamidae) from Sagaing, Myanmar, Evolutionary Systematics 5 (2), pp. 347-357 : 347

Ptyctolaemus chindwinensis sp. nov.

Figures 2 , 3 , 4 , 5 , 6 , 7

Ptyctolaemus gularis : Schulte et al. 2004 (partim): 222-247.

Holotype.

SEABRI 2019120076, adult male, 16 December 2019. Nam E Zu section, Htamanthi Wildlife Sanctuary, Sagaing Division, Myanmar (25°25'57"N, 95°40'48"E, 180 m elevation).

Paratypes.

SEABRI 2019120016, subadult male, 2 December 2019; SEABRI 2019120031, adult male, 5 December 2019; SEABRI 2019120046, adult female, 7 December 2019. All from Nam Pa Gon section, Htamanthi Wildlife Sanctuary, Sagaing Division, Myanmar (25°17'33"N, 95°33'26"E, 170 m elevation).

Etymology.

The specific epithet refers to the Chindwin River, the new species was discovered in its basin.

Diagnosis.

Body size medium, SVL 45.6-83.5 mm, slender, tail long, TAL/SVL 2.24-2.47, limbs long, FLL/SVL 0.48-0.52, HLL/SVL 0.90-0.94. Tympanum concealed. Nuchal crest undeveloped, low and flat. Dorsal scales heterogeneous. The gular region is bright yellow with two or three short black stripes in males and the gular region is greyish white with no stripe in females.

Description of the holotype.

Adult male, habitus slender, slightly compressed laterally, SVL 83.5 mm, TAL 206 mm, TAL/SVL 2.47. Rostral scale crescent, width approximately 3.1 times of height, five scales in contact with rostral edge including the first supralabials; nasal octagonal, separated from rostral by one scale, seven scales in contact with nasal on each side; canthus rostralis sharp, composed of 12 enlarged scales on each side; scales on snout irregular in shape and size; an inverted Y-shaped pattern on the middle of the snout; ten supralabials left and eleven right; orbit 7.2 mm in horizontal diameter; distance from anterior edge of orbit to nostril 5.9 mm, and 9.6 mm to tip of rostral scale; tympanum concealed, covered with smooth, slightly imbricate scales, equal in size to adjacent scales; three enlarged scales posterior and horizontal to orbit, keeled and elevated; temporal area with three enlarged, pointing scales. Mental scale triangular, wider than long, slightly narrower than rostral; mental followed by an infralabial on either side and two postmentals in contact with first infralabials; posterior to postmentals are four chin shields on each side that run parallel to infralabials, anterior portion of first chin shield touching first infralabial, remaining portion of first chin shield and following two chin shields separated from infralabials by one scale row; nine infralabials left and ten right. Gular scales anterior to gular pouch small, rounded, imbricate and slightly mucronate; scales of gular pouch slightly keeled, becoming larger toward center. Nuchal crest poorly developed, composed of 29 conical scales. Scales from angle of jaw to shoulder with feebly keeled, imbricate scales, interspersed with three large pointed scales; small oblique curved fold in front of shoulder. Dorsal scales keeled, imbricate, pointing backwards; mid-dorsal scale row strongly keeled and equal in size to bordering dorsal scales, one row of discontinuous, strongly keeled, enlarged, scales net to the vertebral ridge, separated from the mid-dorsal scale row by three scale rows; lateral scales heterogeneous, majority of scales much smaller than dorsals, feebly keeled, imbricate, interspersed with enlarged strongly keeled scales; lateral scales pointing backwards and downwards. Ventral scales larger than lateral scales, approximately equal in size to largest dorsal scales, strongly keeled, imbricate, mucronate, pointing backwards. Limbs slender, covered dorsally with strongly keeled, imbricate, mucronate scales; ventral surface of limbs with smaller feebly keeled, imbricate, scales; relative length of digits: IV > III > II > V > I, relative length of toes: IV> III > V > II> I; 33/35 subdigital lamellae under fourth toes. Tail slightly compressed laterally, covered with homogenous, strongly keeled, imbricate, scales.

Color of holotype in life.

Dorsal head light brownish grey, several indistinct transverse brown stripes on the anterior portion dorsally, two black spots on the top of the head; lateral head grayish brown, many indistinct radial black stripes around the eye, the two below and posterior to the eye extended to the corner of the mouth; ventral head grayish brown, gular region bright yellow with two horizontal parallel black stripes on the center of each side of the gular pouch, the lengths of the two stripes almost equal and no more than half length of the gular pouch, the two stripes slightly connected up and down, separated by a indistinct thin yellow stripe. Dorsal neck and body light brownish grey with some indistinct slightly symmetrical brown patches beside the vertebral ridge; lateral neck and body flank brownish grey with indistinct purple brown reticulated pattern; the middle of the ventral body white, ventrolateral region purple brown; dorsal side of the limbs brownish grey with some indistinct brown bands; ventral side of the limbs scattered with white and brown. Anterior portion of the tail brownish grey, middle portion of the tail with black and white rings, posterior portion of the tail almost uniform black.

Color of holotype in preservative.

Dorsal head, neck, body, and limbs light brown, transverse stripes on dorsal head became more indistinct, the patches and bands on dorsal body and limbs almost invisible; lateral head light brown, the radial stripes around the eye still visible; lateral side of the neck grey; lateral side of the body brown, the reticulated pattern almost invisible; ventral side of the head, body, and limbs yellowish white, bright yellow on gular region faded; brown and white rings on the tail.

Variations.

The paratypes resemble the holotype in morphometric characteristics, the paratypes merely having smaller body sizes than the holotype. For coloration, the male paratype (SEABRI 2019120031) has an almost uniform light brownish grey dorsal color with no stripes or patches, and the gular region has three black stripes, of which the upper two are parallel and the lower two intersect; the female paratype (SEABRI 2019120046) has more obvious patches on the back and a more obvious reticulated pattern on the body flanks, and the gular region is greyish white with only some tiny black spots but no stripe.

Natural history.

All specimens were collected on withered leaves on the sides of small roads in forests at night while they were asleep. The collection sites are near a tributary of the Chindwin River, but there was no water body within hundreds of meters of the collection sites. There are both primary and secondary forests around the collection sites, and the woods are dense. Other reptiles also found at the site included Bungarus fasciatus (Schneider), Cyrtodactylus mombergi Grismer, Wood, Quah, Thura, Herr & Lin, C. russelli Bauer, Psammodynastes pulverulentus (Boie), and Ptyas korros (Schlegel).

Ptyctolaemus chindwinensis sp. nov. can change its body color within a certain range like most other draconine lizards. When they rest on withered leaves at night, their bodies are pale colored with almost no stripes or patches; when they active are on the ground during the day, their bodies become darker with obvious stripes or patches (Fig. 7 ). The colouration provides camouflage in their preferred habitat.

Distribution.

Ptyctolaemus chindwinensis sp. nov. is currently only known from Htamanthi Wildlife Sanctuary, Sagaing Division, Myanmar (Fig. 8 ).

Comparisons.

Ptyctolaemus chindwinensis sp. nov. can be distinguished from P. gularis and Ptyctolaemus aff. gularis from Tibet, China, by having relatively longer limbs (FLL/SVL 0.48-0.52 vs 0.35-0.45 in P. gularis and Ptyctolaemus aff. gularis , HLL/SVL 0.90-0.94 vs 0.71-0.78 in P. gularis and Ptyctolaemus aff. gularis ), and live colorations of gular region (bright yellow with two or three short black stripes on the center of each side of the gular pouch in males and greyish white with no stripe in females vs. white with three or four long blue or bluish black stripes which occupy most portions of the gular pouch in both sexes in Ptyctolaemus aff. gularis ).

Ptyctolaemus chindwinensis sp. nov. can be distinguished from P. collicristatus by having relatively longer limbs (FLL/SVL 0.48-0.52 vs 0.39-0.45 in P. collicristatus , HLL/SVL 0.90-0.94 vs 0.64-0.74 in P. collicristatus ), a longer tail (TAL/SVL 2.24-2.47 vs 1.77-2.13 in P. collicristatus ), and a lower nuchal crest in the adult males (vs. more prominent nuchal crest in adult males in P. collicristatus ).

Figures

Figure 2. Type series of Ptyctolaemus chindwinensis sp. nov. in preservative. A. Dorsal view; B. Ventral view.

Figure 3. Head views of the holotype (SEABRI 2019120076) of Ptyctolaemus chindwinensis sp. nov. A. Right; B. Left; C. Dorsal; D. Ventral.

Figure 4. The holotype (SEABRI 2019120076) of Ptyctolaemus chindwinensis sp. nov. in life. A. Dorsal view; B. Lateral view; C. Ventral view.

Figure 5. The adult male paratype (SEABRI 2019120031) (A, B) and the adult female paratype (SEABRI 2019120046) (C, D) of Ptyctolaemus chindwinensis sp. nov. in life.

Figure 6. Close up view of the gular regions of Ptyctolaemus chindwinensis sp. nov. in life. A. The holotype (SEABRI 2019120076); B. The subadult male paratype (SEABRI 2019120016); C. The adult male paratype (SEABRI 2019120031); D. The adult female paratype (SEABRI 2019120046).

Figure 7. Different body colors of the subadult male paratype (SEABRI 2019120016) showed in life. A. On withered leaves at night; B. On the ground during the day.

Figure 8. Map showing the type locality (star) of Ptyctolaemus chindwinensis sp. nov., the type locality (square) of P. collicristatus, the locality (dot) of Ptyctolaemus aff. gularis in Tibet, China, the locality (triangle) of Ptyctolaemus cf. gularis in northeastern India, and the locality (pentagon) of Ptyctolaemus sp. in Kachin, Myanmar.