Cyrtodactylus myaleiktaung, Grismer & Wood & Thura & Win & Grismer & Trueblood & Quah, 2018

Grismer, L. Lee, Wood, Perry L., Thura, Myint Kyaw, Win, Nay Myo, Grismer, Marta S., Trueblood, Llyod A. & Quah, Evan S. H., 2018, A re-description of Cyrtodactylus chrysopylos Bauer (Squamata: Gekkonidae) with comments on the adaptive significance of orange coloration in hatchlings and descriptions of two new species from eastern Myanmar (Burma), Zootaxa 4527 (2), pp. 151-185 : 167-169

Cyrtodactylus myaleiktaung sp. nov.

Mya Leik Taung Bent-toed Gecko

( Fig. 4 )

Holotype. Adult female LSUHC 13965 collected on 1 December 2017 at 1030 hrs by Nay Myo Win from Mya Leik Taung , 25.3 km southeast of Mandalay, Aungmyethazan Township, Mandalay District, Mandalay Region, Myanmar (21.77722 N, 96.25138 E; 250 m in elevation).

Diagnosis. Cyrtodactylus myaleiktaung sp. nov. differs from other species of Cyrtodactylus by having the unique combination of the following characters: nine supralabials and infralabials; no gular tubercles; a ventrolateral fold; 57 ventral scales; digits not relatively short; basal subdigital lamellae expanded proximal to digital inflection; 18 subdigital lamellae on the fourth toe; no enlarged femoral scales or pore-bearing femoral scales; no precloacal groove; no enlarged post-precloacal scales; band on nape; six dorsal bands lacking paravertebral elements, regular in shape, wider than interspaces, few dark makings in interspaces, interspaces bearing lightened centers, not edged posteriorly by light-colored tubercles, posterior and anterior borders of bands bold; clusters of enlarged, light-colored scales in ventrolateral fold; and top of head generally unicolor ( Table 5). These characters are scored across all species in the gansi group in Table 3.

Description of holotype. Damaged adult female, SVL 67.4 mm; sections of the skin missing from tip of rostrum, right supralabials, right temporal region, base of nape, anterior gular region, cloacal region, and right forelimb and hind limb; tail missing; head moderate in length (HL/SVL 0.27), width (HW/HL 0.60), somewhat flattened (HD/HL 0.40), distinct from neck, triangular in dorsal profile; lores inflated, prefrontal region concave, canthus rostralis rounded; snout elongate (ES/HL 0.44), rounded in dorsal profile; eye large (ED/HL 0.29); ear opening oval, moderate in size (EL/HL 0.15); eye to ear distance less than diameter of eyeball; rostral rectangular, depressed medially, bordered laterally by external nares and first supralabials; nine (L) rectangular supralabials extending to below midpoint of eye; 9 (L) infralabials tapering smoothly to below posterior margin of eyeball; scales of rostrum and lores flat, slightly larger than granular scales on top of head and occiput; scales on top of head and occiput intermixed with slightly enlarged tubercles; dorsal supraciliaries raised and pointed; mental triangular, bordered laterally by first infralabials and posteriorly by large, left and right trapezoidal postmentals; and gular and throat scales small, granular, grading posteriorly into larger, flatter, smooth, subimbricate to imbricate, pectoral scales that grade posteriorly into larger and imbricate ventral scales.

Body relatively short (AG/SVL 0.46) with well-developed ventrolateral folds; dorsal scales small, interspersed with larger, weakly keeled, semi-regularly arranged tubercles; tubercles extend from top of head onto base of tail; tubercles on occiput and nape smaller than those on posterior portion of body that are larger and keeled; approximately 57 flat, imbricate, ventral scales larger than dorsal scales; large post-precloacal scales present; and no precloacal groove or depression.

Forelimbs moderate in stature, relatively short (FL/SVL 0.15); raised scales of forearm same size as those on body, interspersed with large tubercles; palmar scales slightly raised; digits well-developed, inflected at basal, interphalangeal joints, slightly narrower distal to inflections; claws well-developed, sheathed by a dorsal and ventral scale; enlarged series of scales at base of first digit; hind limbs more robust than forelimbs, moderate in length (TBL/SVL 0.18), covered dorsally by granular scales interspersed with large keeled tubercles and anteriorly by large, flat, imbricate scales; ventral scales of thigh flat, imbricate, slightly larger than dorsals, lacking a row of enlarged or pore-bearing scales; small postfemoral scales grade smoothly into large, flat ventral scales of posteroventral margin of thigh; subtibial scales large, flat, imbricate; plantar scales raised; digits well-developed, inflected at interphalangeal joints; seven expanded subdigital lamellae on fourth toe proximal to inflection, 11 more narrow subdigital lamellae distal to inflection, 18 total subdigital lamellae; and claws well-developed, base of claw sheathed by a dorsal and ventral scale.

Coloration in life ( Fig. 4 ). Dorsal ground color of head body, limbs, and tail pale-yellow to light-brown; top of head unicolor; ventral portion of lores and supralabials darkened; dark postorbital stripe extends across top of ear opening forming a wavy nuchal loop and contacting posterior margin of opposing eyes; wide, dark band on nape; six regularly shaped dorsal body bands (including nape) bear bold anterior and posterior borders and lightened centers; one postsacral band; bands not bordered posteriorly by white tubercles; few faint, dark markings in dorsal interspaces; clusters of enlarged, white scales in ventrolateral folds; forelimbs diffusely mottled; banding on hind limbs slightly more distinct; all ventral surfaces generally beige.

Distribution. Cyrtodactylus myaleiktaung sp. nov. is known only from the type locality of Mya Leik Taung, 25.3 km southeast of Mandalay, Aungmyethazan Township, Mandalay District, Mandalay Region, Myanmar ( Fig. 1 ).

Etymology. The specific epithet myaleiktaung is in reference to the Mya Leik Taung mountain range which is the type locality. It is a noun in apposition, invariable.

Natural History. Mya Leik Taung is an isolated hill on the eastern edge of the Ayeyarwady Basin immediately east of the small village of Kanduin. The hill is dissected east to west by a series of shallow, rocky valleys. Mya Leik Taung reaches nearly 700 m in elevation and its hillsides are covered in sparse scrubby vegetation amongst varying sizes of karstic boulders and outcrops ( Fig. 4 ). The single adult female was collected during the evening at 250 m in elevation.

Comparisons. Cyrtodactylus myaleiktaung sp. nov. differs from all other species in the gansi group by having more ventral scales (57 versus 21–55, collectively), and having body bands with lightened centers. It differs from C. brevidactylus in having 6 versus three or four dorsal bands. Cyrtodactylus myaleiktaung sp. nov. is most closely related to C. chrysopylos and differs further from it by having a 17.0–19.4% uncorrected pairwise sequence divergence.

Remarks. Some (i.e. Dayrat, 2005; Thomas Hbrek, in litt, 2018) have grave concerns about descriptions of new species based on only a single specimen, and posit that this should ‘never’ be done because such a description cannot take into account intraspecific variation that could potentially preclude its specific recognition. Although this is a theoretically noble notion, it is not only incorrect philosophically—as the ontological existence of a species is independent of its diagnosis—but it is counterproductive in reality and bereft of phylogenetic input in practice. Additionally, such tactics would impede biodiversity studies in general and taxonomy in particular. Estimates have shown that 19% of all new vertebrate species described between 2000 and 2010 were based on a single specimen ( Lim et al. 2012) and that number is likely to have increased in the last seven years—an indication that in many circumstances this the logistic reality of constructing species delimitation hypotheses. Furthermore, with wellsupported phylogenetic data such as that herein indicating that the specimen in question is not nested within any other species and shares a 17.0–19.4% uncorrected pairwise sequence divergence from its closest relative, renders any morphological arguments to the contrary moot—regardless of their erroneous conflation of ontology with epistemology ( Frost & Kluge 1994). However, in this case, Cyrtodactylus myaleiktaung sp. nov. has morphological and color pattern characters that distinguish it from all other species in the gansi group thus further eclipsing any assumption that it may be conspecific with any other species. Additionally, the fact that the specimen is damaged has no bearing on its phylogenetic history or genetic distinctiveness which are the data used herein to hypothesize its identity by delimiting its species boundaries. We are concerned about describing a new species based on a single damaged specimen but only because the diagnosis is incomplete, not because it has anything to do with the reality of this specimen representing a distinct independently evolving lineage. We do admit we have knowledge that Mya Leik Taung mountain is being investigated by a cement company wanting to quarry its hillsides for limestone and we felt it prudent to get this species described for potential protective status as soon as possible rather than delay its publication for the sake of a better description. Furthermore, we point out that two other species of the gansi group, C. chrysopylos and C. mandalayensis were also described on the basis of single specimens.

The weak part of recognizing this specimen as a distinct species is not the incomplete diagnosis, but that the species is being delimited on the basis of a single-locus mtDNA phylogeny. It is well-documented that mtDNA phylogenies can reveal significant structure in a data set by recovering sequentially nested monophyletic groups even though within that same data set, nuclear genes can indicate significant gene flow among these groups (e.g. Shaw 2002; Fisher-Reid & Wiens,2011; Toews & Brelsford 2012), thus precluding their species status. This weakens any hypothesis of specific identity based solely on mtDNA data. Nonetheless, given the current data available concerning its phylogenetic relationships and the discrete morphological and color pattern differences separating C. myaleiktaung sp. nov. from its congeners, we regard its specific identity as a testable hypothesis.

Figures

FIGURE 1. Maximum likelihood consensus tree topology of the Cyrtodactylus gansi group with BPP and UFB support values, respectively, at the nodes. Distribution of the species of the C. gansi group in India and Myanmar.

FIGURE 4. A. Habitat of Cyrtodactylus myaleiktaung sp. nov. B and C. Adult female holotype of Cyrtodactylus myaleiktaung sp. nov. from Mya Leik Taung, 25.3 km southeast of Mandalay, Aungmyethazan Township, Mandalay District, Mandalay Region, Myanmar (21.77704 N, 96.25169 E; 255 m in elevation).