Cyrtodactylus ywanganensis, Grismer & Wood & Thura & Quah & Grismer & Murdoch & Espinoza & Lin, 2018

Grismer, L. Lee, Wood, Perry L., Thura, Myint Kyaw, Quah, Evan S. H., Grismer, Marta S., Murdoch, Matthew L., Espinoza, Robert E. & Lin, Aung, 2018, A new Cyrtodactylus Gray, 1827 (Squamata, Gekkonidae) from the Shan Hills and the biogeography of Bent-toed Geckos from eastern Myanmar, Zootaxa 4446 (4), pp. 477-500 : 489-496

Cyrtodactylus ywanganensis sp. nov.

Suggested common name: Ywangan Bent-toed Gecko

Fig. 6

Holotype. Adult female LSUHC 13758 collected on 24 October 2017 at 2300 hrs by L. Lee Grismer, Robert E. Espinoza, Matthew L. Murdoch, Myint Kyaw Thura, Evan S. H. Quah, and Tun Oo from 2.7 km southwest of Ywangan , Ywangan Township, Taunggyi District, Shan State, Myanmar (21.14643°N, 96.42178°E; 1157 m in elevation).

Paratypes. Adult female paratype LSUHC 13757 bears the same collection data as the holotype. Adult male paratype LSUHC 13712 and subadult male paratype LSUHC 13711 bear the same collection data as the holotype except they were collected on 23 October 2017 at 2200 hrs.

Diagnosis. Cyrtodactylus ywanganensis sp. nov. differs from all congeners by having the unique combination of a maximum SVL of 96.1 mm; seven supralabials; six infralabials; 32–35 paravertebral tubercles; 21–25 longitudinal rows of body tubercles; 34–36 ventral scales; relatively long digits with seven or eight expanded subdigital lamellae proximal to the digital inflection on the fourth toe, 12–14 unmodified distal subdigital lamellae, 19–21 total subdigital lamellae; raised, strongly keeled, dorsal body tubercles; tubercles not extending beyond base of tail; enlarged femoral and precloacal scales continuous; enlarged proximal femoral scales equal in size to the enlarged distal femoral scales; 28–30 enlarged femoral scales; 20 femoral pores in male; eight or nine precloacal pores in male; femoral and precloacal pore-bearing scales not continuous; eight or nine enlarged precloacal scales; three rows of enlarged post-precloacal scales; medial subcaudal scales twice as wide as long, not extending onto lateral surface of tail; top of head darkly blotched in adults, no yellow reticulum; nuchal loop not divided medially, pronounced anterior azygous notch, posterior border straight; four jagged, dark, dorsal bands lacking paravertebral elements, wider than interspaces with no lightened centers, edged with yellow tubercles; no band on nape; dark markings in dorsal interspaces; ventrolateral folds not whitish; anterodrosal margins of thighs and brachia darkly pigmented; seven light caudal bands bearing dark markings, encircling tail; seven dark caudal bands wider than light caudal bands; and mature regenerated tail spotted. These characters are scored against all other species in the linnwayensis group ( Table 3) and all other Burmese species of the Indochinese clade in Grismer et al. (2017a:Table 8).

Description of holotype. Adult female SVL 90.5 mm; head moderate in length (HL/SVL 0.29), wide (HW/HL 0.69), flat (HD/HL 0.38), distinct from neck, triangular in dorsal profile; lores inflated, prefrontal region concave, canthus rostralis rounded; snout elongate (ES/HL 0.43), rounded in dorsal profile, broad in lateral profile; eye large (ED/HL 0.25); ear opening oval, small (EL/HL 0.09); eye to ear distance greater than diameter of eye; rostral rectangular, partially divided dorsally, bordered posteriorly by supranasals and azygous postnasal, laterally by first supralabials; external nares bordered anteriorly by rostral, dorsally by supranasals, posteriorly by two postnasals, and ventrally by first supralabials; 7(R,L) rectangular supralabials extending to below midpoint of eye; 6(R,L) infralabials tapering posteriorly to below orbit; 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 small tubercles; dorsal superciliaries weakly pointed and directed posteriorly; mental triangular, bordered laterally by first infralabials and posteriorly by large left and right trapezoidal postmentals which contact medially for 50% of their length posterior to mental; two rows of variably enlarged chinshields bordering all infralabials; gular and throat scales granular, grading posteriorly into larger, subimbricate pectoral and ventral scales.

Body relatively short (AGL/SVL 0.43) with well-defined ventrolateral folds; dorsal scales small, raised and interspersed with large, raised, semi-regularly arranged, keeled tubercles; tubercles extend from nape onto base of tail but no farther; tubercles on nape smaller than those on posterior portion of body; 32 paravertebral tubercles; approximately 25 longitudinal rows of dorsal tubercles; 35 flat, subimbricate, ventral scales larger than dorsal scales; nine enlarged precloacal scales; three rows of large, post-precloacal scales; and no deep precloacal groove or depression.

Forelimbs moderate in stature, relatively short (FL/SVL 0.17); slightly raised, juxtaposed scales of forearm larger than those on body, intermixed with tubercles; palmar scales slightly raised; digits well-developed, relatively long, inflected at basal, interphalangeal joints; digits much more narrow distal to inflections; widened proximal subdigital lamellae do not extend onto palm; webbing at base of digit; claws well-developed, sheathed by a dorsal and ventral scale at base; hind limbs more robust than forelimbs, moderate in length (TBL/SVL 0.20), covered dorsally by small, raised, juxtaposed scales intermixed with large tubercles and bearing flat, slightly larger scales anteriorly; ventral femoral scales imbricate, larger than dorsals; one row of 15(R,L) enlarged femoral scales in contact with enlarged precloacal scales; enlarged femoral scales nearly equal in size; small, postfemoral scales form an abrupt union with larger, flat ventral scales of posteroventral margin of thigh; subtibial scales flat, imbricate; plantar scales raised; digits relatively long, well-developed, inflected at basal, interphalangeal joints; eight (R,L) transversely expanded subdigital lamellae on fourth toe proximal to joint inflection that do not extend onto sole, 13 (R,L) unmodified subdigital lamellae distal to inflection; and claws well-developed, base of claw sheathed by a dorsal and ventral scale.

Tail complete, original, moderate in proportions, 110.0 mm in length, 8.0 mm in width at base, tapering to a point, TL/SVL (1.22); dorsal scales of tail flat; median row of transversely expanded subcaudal scales twice as wide as long, not extending onto lateral subcaudal region; three enlarged postcloacal tubercles at base of tail on hemipenal swellings; and postcloacal scales flat.

Coloration in life ( Fig. 6 ). Dorsal ground color of head, body, and limbs brown; top of head and rostrum bearing large dark-brown blotches edged in yellow; superciliary scales yellow; wide, dark-brown, nuchal band edged in yellow, bearing a deep azygous anterior notch and a straight posterior margin; no band on nape; four jagged body bands bearing dark centers, wider than interspaces, not bearing paravertebral elements and edged with yellow tubercles; one dark postsacral band edged with yellow tubercles; interspaces bearing faint, dark markings; thin, yellow, irregularly shaped bands and small spots on limbs; dorsal margins of brachia and thighs darkly pigmented; ventrolateral body folds darkly pigmented; ventral surfaces beige, dusky in appearance; and tail original, bearing seven dark wide caudal bands and seven much narrower white caudal bands with dark markings that encircle tail.

Variation ( Fig. 6 ). The paratypes closely resemble the holotype in all aspects of coloration and pattern. Paratypes LSUHC13712 and 13757 have fully regenerated spotted tails. Subadult male LSUHC 13711 has a broken tail with two very small regenerating sections, is lacking femoral pores, and has less yellow in its color pattern. Additional variation in meristic and mensural characters are presented in Table 4.

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Distribution. Cyrtodactylus ywaganensis sp. nov. is known only from the type locality 2.7 km southwest of Ywangan, Ywangan Township, Taunggyi District, Shan State, Myanmar but is likely to occur in other nearby limestone outcroppings to the west up to the crest of the Shan Plateau before it descends steeply down to the eastern edge of the Ayeyerwady Basin ( Fig. 1 ).

Etymology. The specific epithet, ywanganensis , is a noun in apposition in reference to the type locality being near the town of Ywangan, Shan State.

Natural history. The region surrounding the type locality of Cyrtodactylus ywanganensis sp. nov. is a generally open, flat, and disturbed landscape with low, short, vegetated karstic ridges and small, isolated, karst outcrops scattered throughout the area ( Fig. 7 ). At the base of some of the karstic ridges are narrow (0.05–1 m across), vertical shafts that extend underground for unknown distances. All specimens collected and observed were near the openings of these shafts. The subadult male LSUHC 13711, was found at night on the face of a karst wall beneath a large overhang immediately above a shaft opening. It retreated into a crack but was coaxed out into the open and captured. Approximately 50 m away, adult male LSUHC 13712 was found the same night at the entrance to another shaft and was captured 2 m below the opening while attempting to escape. Adult female LSUHC 13757 was found in the same place as LSUHC 13711 the next day but lower on the wall below the shaft opening where it was relatively dark. It too was captured as it descended to approximately 3 m down the shaft in an attempt to escape. Another specimen was seen later that day at another shaft opening but was able to escape. The adult female LSUHC 13758 was found at night 2 m above ground level on the narrow branch of a tree growing out of a shaft. It is clear C. ywanganensis sp. nov. is closely associated with these small, karstic, cave-like microhabitats. The depths to which these shafts extend and the extent (if any) of their subterranean connectivity is unknown but clearly these geckos have to be interacting with each other and it is unlikely they are doing so above ground off the karst. From 1800–2400 hrs on two consecutive nights, seven people surveyed several isolated karst outcrops in the open areas that contained cracks and holes suitable for Cyrtodactylus but only Hemidactylus and Hemiphyllodacylus were found.

Comparisons. The phylogenetic relationships indicate that Cyrtodactylus ywanganensis sp. nov. is nested within the linnwayensis group. The PCA and DAPC analyses indicate that C. ywanganensis sp. nov. is morphospatially separate from other species of the linnwayensis group along the first three principal components (PC) with PC1 accounting for 41% of the total variation in the data set ( Fig. 4 ; Table 5) and loading most heavily for numbers of paravertebral tubercles (PVT), expanded and total numbers of fourth toe lamellae (TL and TEL), longitudinal rows of tubercles (LRT), body bands (BB), and post-precloacal scale rows (PPS). PC2, which accounts for 18% of the total variation loads most heavily for infralabials (IL) and supralabials (SL). PC 3 accounts for an additional 11% of the total variation and loads most heavily for the number of unmodified toe lamellae (TLN). The ANOVA and Tukey HSD analyses indicate C. ywanganensis sp. nov. has several meristic characters whose mean values differ significantly (p Ẽ 0.05) and discreetly (i.e. no overlap in the range of variation) from the other members of the linnwayensis group ( Tables 3, 6).

Remarks. Grismer et al. (2017a) left open the possibility that Cyrtodactylus shwetaungorum and C. linnwayensis were conspecific and that their morphological dissimilarities and uncorrected pairwise genetic distance of 10.2% was a result of sampling error. They noted that additional populations from the intervening area would bear significantly on this question. Cyrtodactylus ywanganensis sp. nov. from the intervening area ( Fig. 1 ) is not morphologically intermediate between C. shwetaungorum and C. linnwayensis in any of the significantly different characters except for the number of post-precloacal scale rows ( Fig. 5 ). Additionally, C. ywanganensis sp. nov. is morphospacially unique and does not cluster between the other two species ( Fig. 4 ). Furthermore, C. ywanganensis sp. nov. is more strongly tuberculated, has dorsal bands lacking lightened centers, lacks a lightcolored reticulum on the top of the head, and has seven versus eight or nine light-colored caudal bands. These, along with its 6.5% sequence divergence from its sister species C. linnwayensis , are taken as evidence that these three populations constitute independent, non-reticulating lineages on independent evolutionary trajectories (i.e. they are different species). We believe that based on the color pattern of a fourth population of Cyrtodactylus discovered by Alice Hughes from Kyauk Hnat Cave in the Shan Hills approximately 4.75 km southwest of the Linn Way depression ( Fig. 1 ), that it too is a member of the linnwayensis group and most likely C. linnwayensis . Like all other members of this group, it has the unique combination of an anterior azygous notch in the nuchal loop, no band on the nape, four jagged body bands wider than the interspaces edged with light-colored tubercles, and the body tubercles do not extend past the base of the tail ( Fig. 6 ).

species group. Abbreviations are in the Materials and methods.

Figures

FIGURE 1. Distribution and relationships among species of the linnwayensis group in the Shan Hills, Shan State, Myanmar. Branch lengths are arbitrary and do not reflect genetic distances. Starred localities represent type localities.

FIGURE 4. Principle component analysis (PCA) with biplot overlay, discriminant analysis of principles components (DAPC), and three-dimensional representation of the first three principle components (PC1, PC2, PC3) illustrating the morphospatial separation of the three species of the linnwayensis group.

FIGURE 5. Box plots of the characters having statistically significant mean differences between Cyrtodactylus ywanganensis sp. nov. and/or C. linnwayesnsis and C. shwetaungorum illustrating the lack of overall intermediacy of C. ywanganensis sp. nov. between C. linnwayensis and C. shwetaungorum. Colored boxes represent the interquartile range, the black horizontal bar is the median, and the light-blue spot is the mean.

FIGURE 6. Cyrtodactylus ywanganensis sp. nov. from the type locality 2.7 km southwest of Ywangan, Ywangan Township, Taunggyi District, Shan State, Myanmar: (A) juvenile male paratype LSUHC 13711, (B) adult male paratype LSUHC 13712, and (C) adult female holotype LSUHC 13758. (D) Cyrtodactylus cf. linnwayensis. LSUDPC 10754 from Kyauk Hnat Cave in the Shan Hills, Shan State, approximately 4.75 km soutwest of the Linn way depression (photograph by Alice Hughs).

FIGURE 7. A and B orientation of the vertical shafts (white arrows) at the base of karst boulders at the type locality of Cyrtodactylus ywanganensis sp. nov. 2.7 km southwest of Ywangan, Ywangan Township, Taunggyi District, Shan State, Myanmar. C. General habitat structure of the type locality.