Ctenotus rhabdotus, Rabosky & Doughty & Huang, 2017

Rabosky, Daniel L., Doughty, Paul & Huang, Huateng, 2017, Lizards in pinstripes: morphological and genomic evidence for two new species of scincid lizards within Ctenotus piankai Storr and C. duricola Storr (Reptilia: Scincidae) in the Australian arid zone, Zootaxa 4303 (1), pp. 1-26 : 19-20

Ctenotus rhabdotus sp. nov.

Rabosky & Doughty

( Figs. 1 , 3 B, 6, 15)

Holotype. WAM R157440, female, collected from the Tanami Desert, WA (19°34'47"S, 128°51'53"E) by R.J. Teale et al. (Biota Environmental Sciences) on 3 October 2004.

Measurements of holotype: SVL 51 mm; TL 115 mm; HL 9.9 mm; HW 6.6 mm; HD 4.4 mm; 4ToeL 8.6 mm; ToeLam 25; MBSR 28; SupLab 8 (left) and 9 (right); InfLab 8; supraciliaries 8; EarLob 4 each side.

Paratypes. WAM R 110581, female, location as for holotype ; WAM R119711, female, WAM R119717, subadult, Emma Gorge, Cockburn Range, WA (15°50'S, 128°02'E); WAM R157412, male, location as for holotype .

Diagnosis. A small-bodied (to 61 mm SVL), elongate Ctenotus , nasals in contact, prefrontals usually separated, 26 or 28 mid-body scale rows, 21–26 compressed rounded lamellae under toes with broad callus, from 7–9 (usually eight) supralabials and supraciliary scales; pattern simple and full including six (occasionally eight) pale narrow longitudinal stripes on a blackish-brown dorsum, dorsal stripes not continuing on head to snout, tail not red or blue, pale lateral stripe only slightly wider than pale paravertebral and dorsolateral stripes, absence of upper lateral row of spots, dark vertebral stripe continues anteriorly to parietals, parietals with pale irregular blotching, pale dorsolateral stripes continue anteriorly to eye, pale paravertebral stripes join on tail at or posterior to level of heel of extended hind limb, lower labial scales variably stippled.

Description of holotype. Head triangular, with snout narrowing to rounded tip; body long and cylindrical with flattened ventrum, neck only weakly constricted from head and body, concavity posterior to forelimbs; limbs short and well-developed, palmar and plantar surfaces with raised conical to triangular scales with rounded tips, pentadactyl, finger length: 3>4>2>5>1, toe length: 4>3>2>5>1, subdigitial lamellae rounded to broadly callose, not strongly laterally compressed as in C. piankai , claws long and recurved; tail long and thin, tapering to a fine point.

Dorsal scales smooth, flat, reflective and imbricate, posterior edge of scale convex; scales on midline of dorsum widest, decreasing in size to ventrolateral edge; on tail, ventral scale rows along midline much wider than other scale rows, distal portion of tail often regenerated.

Nostril located in center of nasal scale and directed anteriorly, frontoparietals divided, supraoculars four (2nd largest), superciliaries, loreals two, preoculars two, one presubocular, supralabials eight (left) and nine (right), infralabials seven, upper eyelid with translucent scales, lower eyelid scaly, ear opening D-shaped with four ear lobules on anterior edge, mental with straight posterior edge, gulars imbricate decreasing in size posteriorly towards neck then increasing again on ventrum; two greatly enlarged scales anterior to cloaca.

Coloration of holotype. Simple pattern of medium to dark blackish-brown background and six pale longitudinal stripes; anterior portion of dark dorsal scales lighter than posterior portion; vertebral stripe darker than other areas of background color, scales uniformly dark; four pale dorsal stripes narrow (<½ scale width); two lateral stripes only slightly wider and solid, continuing forwards to ear; paravertebral stripe continues anteriorly to parietals or anterior-most nuchals; dorsolateral stripe continues unbroken to fourth supraocular; purplish-black eyes just visible through dark medial supraocular scales; ear lobules pale; lower labials variably stippled, especially in region of sutures; all ventral surfaces pale and immaculate.

Variation. Variation in continuous and meristic characters is summarized in Table 1. Occasionally eight longitudinal stripes (versus six on the holotype). In some specimens, a row of poorly-formed pale flecks is observed between pale dorsolateral and lateral lines, usually restricted to the fore-body. Ground color of legs, arms, and tail light reddish-brown to tan; arm with 4–6 faint alternating light and dark longitudinal stripes; hind limb with 6–8 more contrasting light and dark longitudinal stripes; on tail, pale paravertebral stripes usually join at the level of the heel of extended leg.

Habitat. Collection notes with specimens indicate occurrence on sandy plains to clay on limestone to rocky outcrops with spinifex cover, and also including eucalyptus (e.g. Eucalpytus collina) and acacia in open tropical woodlands.

Distribution. In Western Australia it occurs throughout the semi-arid southern Kimberley region including Windjana Gorge, Mornington Station, Fitzroy Crossing, Cockburn Range and Kununurra, in the north-western Great Sandy Desert including Purnululu National Park and Balgo Hills, and in the northern Tanami Desert including the Victoria River region of the Northern Territory ( Fig. 4 ).

Etymology. The specific name rhabdotus is derived from the Greek rhabdos for lined, in reference to the long thin pale lines on a dark background color in this species. Suggested common name: Kimberley Lined Ctenotus . Remarks. This species’ distribution is unlike that of other species—it inhabits the southern Kimberley and far northern Tanami Desert regions, but appears to be replaced by C. piankai in the Great Sandy Desert and deserts to the south. The extent of its distribution in the NT is approximate. Ctenotus rhabodotus sp. nov. is broadly sympatric or parapatric with C. piankai near Wolfe Creek meteor crater and perhaps elsewhere along the margin of the southern Kimberley. However, sampling from the northern Great Sandy Desert is extremely limited.

Figures

FIGURE 1. Photographs in life of Ctenotus piankai senso lato individuals. A) Yamarna, WA (photo: M. Peterson); B) Birksgate Range, SA (SAMA R 45385; photo: M. Hutchinson); C) Mornington Station, WA (photo: S. L. Macdonald); D) Tanami Desert, WA (photo: G. Harold).

FIGURE 3. Lateral-dorsal perspective of the forebodies of Ctenotus. From top to bottom: A) C. piankai (WAM R 108934), B) C. rhabdotus sp. nov. (WAM R 110581), C) C. duricola (WAM R 111876), and D) C. pallasotus sp. nov. (WAM R 119931). Scale bar is 10 mm.

FIGURE 4. (A) Geographic distribution of morphological forms within the nominate species ‘ C. piankai ’ (blue triangles, gray circles) and ‘ C. duricola ’ (red circles, yellow triangles). Relative to C. piankai from the interior deserts (blue triangles), northern populations from the Kimberley, Ord, Victoria River and northern Tanami desert (gray circles) are characterized by darker ground coloration, more midbody scale rows, and dorsal stripes that extend anteriorly onto the parietal scales (Figs. 1, 3). (B) Distribution of ‘ clean’ (red circles) and ‘ spotted’ (yellow triangles) morphological forms within ‘ C. duricola ’ in the Pilbara region of Western Australia. The ‘ clean’ morphology (Figs. 2 A, B; Fig. 3 C) is largely restricted to the eastern Pilbara, although several individuals from the westernmost edge of the range of C. duricola (North West Cape and Barrow Island) were observed to have this morphology. Several geographic features of north-western Australia discussed in the text are labeled in Fig. 4 B: NWC, North West Cape peninsula; D, De Grey River; F: Fortescue River Basin, AR, Ashburton River.