Cyrtodactylus chaunghanakwaensis, Grismer & Wood & Thura & Quah & Murdoch & Grismer & Herr & Lin & Kyaw, 2018

Grismer, L. Lee, Wood, Perry L., Thura, Myint Kyaw, Quah, Evan S. H., Murdoch, Matthew L., Grismer, Marta S., Herr, Mark W., Lin, Aung & Kyaw, Htet, 2018, Three more new species of Cyrtodactylus (Squamata: Gekkonidae) from the Salween Basin of eastern Myanmar underscore the urgent need for the conservation of karst habitats, Journal of Natural History 52 (19 - 20), pp. 1243-1294 : 1266-1282

Cyrtodactylus chaunghanakwaensis sp. nov.

Chaunghanakwa Hill bent-toed gecko ( Figures 8–11 )

Holotype

Adult male LSUHC 13305 collected on 13 May 2017 at 2000 hrs by Myint Kyaw Thura, Mark W. Herr, L. Lee Grismer, Perry L. Wood, Jr., Matthew L. Murdoch, Evan S.H. Quah, and Htet Kyaw from Chaunghanakwa Hill, 50 km south-east of Mawlamyine, Mawlamyine District , Mon State, Myanmar (16.18456°N, 97.98814°E; 14 m in elevation).

Paratypes

Adult male paratypes LSUHC 13295 , 13298 , 13300 , 13302 , 13308 , and 13312–14 and adult female paratypes LSUHC 13294 , 13296–97 , 13299 , 13301 , 13303–04 , 13306–07 , 13309–11 , 13315–16 , 13321 bear the same collecting data as the type series .

Diagnosis

Cyrtodactylus chaunghanakwaensis sp. nov. differs from all congeners by having the unique combination of a maximum SVL of 76.3 mm; 8–11 supralabials; 7–9 infralabials; 31–36 paravertebral tubercles; 17–22 longitudinal rows of body tubercles; 23–27 longitudinal rows of ventral scales ventral scales; relatively long digits with 6–9 expanded subdigital lamellae proximal to the digital inflexion on the fourth toe, 11–14 unmodified distal subdigital lamellae, 18–21 total subdigital lamellae; dorsal body tubercles low, weakly keeled in adults; tubercles extendind beyond base of tail; enlarged femoral and precloacal scales continuous; enlarged proximal femoral scales greater than one-half the size of enlarged distal femoral scales; 27–32 enlarged femoral scales; 27–32 femoral pores in males; 9–11 precloacal pores in males; femoral and precloacal pore-bearing scales continuous; 9–12 enlarged precloacal scales; two or three rows of enlarged postprecloacal scales; medial subcaudal scales 3 times as wide as long, extending onto lateral surface of tail; top of head darkly mottled, no yellow reticulum; nuchal loop not divided (Continued) (Continued) (Continued) (Continued) medially, no pronounced anterior azygous notch, posterior border jagged; 5–7 jagged, dark, dorsal bands bearing paravertebral elements, wider than interspaces with variably lightened centres, variably edged with white tubercles; nape band present; dark markings in dorsal interspaces; ventrolateral folds not whitish; anterodrosal margins of thighs and brachia darkly pigmented; 10–14 light caudal bands bearing dark markings, not encircling tail; 11–15 dark caudal bands wider than light caudal bands; and mature regenerated tail not spotted. These characters are scored against all other species in the sinyineensis group ( Table 4) and all other Burmese species of the Indochinese clade in Grismer et al. (2017a, table 8).

Description of holotype

Adult male SVL 75.0 mm; head moderate in length (HL/SVL 0.30), wide (HW/HL 0.69), flat (HD/HL 0.40), distinct from neck, triangular in dorsal profile; lores inflated, prefrontal region concave, canthus rostralis rounded; snout elongate (ES/HL 0.41), rounded in dorsal profile, not flat in lateral profile; eye large (ED/HL 0.27); ear opening round, moderate in size (EL/HL 0.07); eye-to-ear distance greater than diameter of eye; rostral rectangular, depressed dorsomedially, bearing a short dorsal cleft, bordered posteriorly by left and right supranasals and one small azygous internasal, laterally by first supralabials; external nares bordered anteriorly by rostral, dorsally by supranasal, posteriorly by three postnasals, ventrally by first supralabial; 8 R, 9 L square supralabials extending to below midpoint of eye; 8 (R, L) infralabials tapering posteriorly to below midpoint of eye; scales of rostrum and lores slightly raised, larger than granular scales on top of head and occiput; scales on top of head and occiput intermixed with minute tubercles; dorsal superciliaries not elongate or keeled; mental triangular, bordered laterally by first infralabials and posteriorly by large left and right trapezoidal postmentals contacting medially for 50% of their length posterior to mental; one row of slightly enlarged chinshields bordering infralabials, first chinshield largest; and gular and throat scales small, flat, grading posteriorly into larger, subimbricate pectoral and ventral scales.

Body relatively short (AG/SVL 0.41) with ventrolateral folds; dorsal scales small, raised and interspersed with larger, low, subconical, semi-regularly arranged, weakly keeled tubercles; tubercles extend from occiput to beyond base of tail; tubercles on nape smaller than those on posterior portion of body, more weakly keeled; approximately 18 longitudinal rows of body tubercles; 31 paravertebral tubercles; 25 flat, subimbricate, ventral scales larger than dorsal scales; 10 enlarged pore-bearing precloacal scales; three rows of large post-precloacal scales; and no deep, precloacal groove or depression.

Fore limbs moderate in stature, relatively short (FL/SVL 0.16); raised scales of forearm larger than those on body, interspersed with slightly enlarged tubercles; palmar scales flat; digits well developed, relatively long, inflected at basal, interphalangeal joints; digits narrow distal to inflexions; widened proximal subdigital lamellae do not extend onto body of palm; claws well developed, sheathed by a dorsal and a ventral scale at base; hind limbs more robust than fore limbs, moderate in length (TBL/SVL 0.19), covered dorsally by granular scales intermixed with large tubercles and bearing flat, slightly larger scales anteriorly; ventral scales of thigh flat, imbricate, larger than dorsals, one row of 14 (R, L) enlarged femoral scales in contact with enlarged precloacal scales; enlarged femoral scales generally equal in size; 14 (R, L) femoral pores; pore-bearing femoral and precloacal scales in contact; subtibial scales flat, imbricate; small postfemoral scales form abrupt union with larger, flat ventral scales of posteroventral margin of thigh; plantar scales slightly raised; digits relatively long, well developed, inflected at basal interphalangeal joints; seven (R, L) transversely expanded subdigital lamellae on fourth toe proximal to joint inflexion, 11 (R, L) unmodified subdigital lamellae distal to inflexion, 18 total subdigital lamellae; claws well developed, base of claw sheathed by a dorsal and ventral scale.

Tail moderate in proportions, original, 101.0 mm in length, last 12.7 mm regenerated, 8.8 mm in width at base, tapering to a point; dorsal scales of original portion of tail flat; median subcaudal scales of original portion of tail 3 times as wide as long, extending onto lateral surface of tail; 4 (R), 3 (L) enlarged postcloacal tubercles at base of tail on hemipenal swellings; and postcloacal scales flat.

Colouration in life ( Figure 8 )

Dorsal ground colour of head, body and limbs tan; top of head and rostrum bearing diffuse thick, dark-brown blotches, no yellow reticulum; rostrum solid brown except for faint, small, yellowish markings; superciliary scales dull-yellow; dark-brown, irregularly shaped, nuchal band un-notched anteromedially and bearing a jagged posterior margin with two large, posterior projections; short, jagged W-shaped band on nape; six jagged body bands not bearing lightened centres, wider than interspaces, bearing distinct paravertebral elements and variably edged with white tubercles, some bands bifurcating laterally; interspaces bearing large dark markings laterally and small, dark vertebral markings; one irregularly shaped sacral band; limbs bearing diffuse light-coloured bands, anterodorsal margins of brachia and thighs pigmented, thighs bearing yellowish tubercles; ventrolateral body fold not whitish; ventral surfaces of head, body and limbs dull white with weak, dark pigmentation peripherally; original portion of tail bearing 10 light caudal bands with faint dark markings, regenerated portion nearly solid black; 10 dark caudal bands wider than light caudal bands; and subcaudal region darkly mottled.

Variation ( Figures 8–11 )

The paratypes closely approach the holotype in most aspects of colouration and pattern. The overall pattern of LSUHC 13297, 13303, 13313, and 13306 is not as contrasted and is less boldly marked. That of LSUHC 13300 is more contrasted with less interspace mottling. Juvenile specimens LSUHC 13316–18 and 13320 are much less boldly marked and generally yellowish overall with light-brown dorsal bands and weak head mottling. As lizards grow, the dark markings expand and turn to dark brown, giving the lizards a much darker overall appearance. LSUHC 13294 is leucistic and bears a general magenta hue with tan speckling on the body and poorly defined caudal bands ( Figure 10 ). Additional variation in meristic and mensural characters is presented in Table 8.

Distribution

Cyrtodactylus chaunghanakwaensis sp. nov. is known only from Chaunghahakwa Hill, 50 km south-east of Mawlamyine, Mawlamyine District, Mon State, Myanmar ( Figure 6 ).

Etymology

The specific epithet, chaunghanakwaensis , is a noun in apposition in reference to the type locality of Chaunghahakwa Hill.

Natural history

Chaunghahakwa Hill is a crescent-shaped ridge reaching 383 m in elevation. It is approximately 320 m in length along its curved axis and approximately 79 m in diameter at its widest central point. Its eastern end is capped by a much smaller karst tower, and a karst hill lies 1 km off its south-facing flank. The topography of this hill is notably different from that of nearby hills in the basin in that much of its southern and northern faces is deeply incised by steep narrow canyons and recesses that are not suitable for agriculture but maintain significant tracts of primary forest ( Figure 12 ). The limestone habitat here is ideal for Cyrtodactylus , with fissures, deep cracks, small side canyons, shallow caves, and boulders and their associated rocky rubble. Due to safety concerns we were only allowed to survey the area at night for 45 minutes, but in that time period we saw at least 50 C. chaunghanakwaensis sp. nov. The lizards were found in every microhabitat conceivable – on the ground, on the limestone at varying heights, in the small caves, and on the vegetation. There seemed to be no strict association with limestone, but rather this species appears to be a scansorial habitat generalist. Lizards were even seen in a small cave during a daytime reconnaissance. Small juveniles were observed but no hatchings or gravid females, indicating that the reproductive season occurs before May, most likely during the rainy season when resources are more abundant.

Comparisons

Ordination of the meristic characters along PC1 and PC2 indicate that Cyrtodactylus chaunghanakwaensis sp. nov. is generally well separated from all other species in morphospace. In the DAPC, two outlying individuals fall within the 95% confidence ellipse of C. naungkayaingensis sp. ( Figure 3 ). Characters that differentiate C. chaunghanakwaensis sp. nov. from C. bayinnyiensis sp. nov. are presented above in the comparisons sections for the latter. Cyrtodactylus chaunghanakwaensis sp. nov. differs from all other species of the sinyineensis group by having low, weakly keeled body tubercles as opposed to raised, strongly keeled tubercles. It differs further from C. aequalis , C. naungkayainensis sp. nov., C. sinyineenesis and C. welpyanensis in the males having continuous pore-bearing femoral and precloacal scales as opposed to these scales being discontinuous. It differs further from C. sinyineenesis and C. welpyanensis in that the dorsal bands bear paravertebral elements as opposed to lacking them. It differs further from C. aequalis and C. sinyineensis in having a smaller maximum SVL (76.3 mm vs 87.0– 91.6 mm, collectively). The phylogenetic analyses recover C. chaunghanakwaensis sp. nov. as the sister species of C. dammathetensis sp. nov. ( Figure 6 ), from which it differs by having significantly (p <0.05) different mean values of dorsal body bands, enlarged femoral scales, longitudinal rows of body tubercles, enlarged precloacal scales, and expanded proximal subdigital lamellae on the fourth toe ( Table 4). Table 4 lists other

meristic characters of C. chaunghanakwaensis sp. nov. that differ significantly from other species of the sinyineensis group.

Figures

Figure 3. Plots of the principal component (PC) analysis ordinations along PC1 and PC2, and PC2 and PC3; and the discriminant analysis of principal components (DAPC) showing the morphospatial relationships of the species of the sinyineensis group.

Figure 6. Distribution of the Burmese species of Cyrtodactylus from the Salween Basin and the phylogenetic relationships of the species of the sinyineensis group. Black circles denote nodes with Bayesian posterior probability (BI) support>0.95 and Maximum Likelihood bootstrap support>95. Grey circles denotes the node with only BI support>0.95.

Figure 8. (a) Adult male holotype of Cyrtodactylus chaunghanakwaensis sp. nov. (LSUHC 13305) from Chaunghanakwa Hill, 50 km south-east of Mawlamyine, Mawlamyine District, Mon State, Myanmar. (b) Adult female paratype of C. chaunghanakwaensis sp. nov. (LSUHC 13306) from the type locality.

Figure 9. (a) Adult female paratype of Cyrtodactylus chaunghanakwaensis sp. nov. (LSUHC 13299) from the type locality of Chaunghanakwa Hill, 50 km south-east of Mawlamyine, Mawlamyine District, Mon State, Myanmar. (b) Adult male paratype of C. chaunghanakwaensis sp. nov. (LSUHC 13308) from the type locality.

Figure 10. (a) Adult female leucistic paratype of Cyrtodactylus chaunghanakwaensis sp. nov. (LSUHC 13294) from the type locality of Chaunghanakwa Hill, 50 km south-east of Mawlamyine, Mawlamyine District, Mon State, Myanmar. (b) Juvenile paratype of C. chaunghanakwaensis sp. nov. (LSUHC 13317) from the type locality.

Figure 11. (a) Female paratypes of Cyrtodactylus chaunghanakwaensis sp. nov. from Chaunghanakwa Hill, 50 km south-east of Mawlamyine, Mawlamyine District, Mon State, Myanmar. (b) Male paratypes of C. chaunghanakwaensis sp. nov. from the type locality, and additional juveniles not part of the type series.

Figure 12. (a) Chaunghanakwa Hill, 50 km south-east of Mawlamyine, Mawlamyine District, Mon State, Myanmar. (b) Primary forest and karst microhabiat structure along the southern flank of Chaunghanakwa Hill.