Ctenotus piankai duricola Storr, 1975

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 : 16-18

Ctenotus piankai duricola Storr, 1975 : p. 239.

Eastern Pilbara Lined Ctenotus

( Figs. 2 , 3 C, 7, 14)

Holotype. WAM R17163 (female), collected from Mt Edgar, WA, Australia (21°19' S, 120°02' E) by G.M. Storr & B.T. Clay on 15 February 1961.

Measurements of holotype: SVL 54 mm; TL 18 mm (broken); HL 10.6 mm; HW 7.2 mm; HD 6.5 mm; 4ToeL 7.8 mm; ToeLam 24; MBSR 28; SupLab 8; InfLab 8; supraciliaries 8; EarLob 3 (left) and 4 (right).

Paratypes. WAM R12629 (female), Woodstock ; WAM R20115* (field tag—231) (damaged), Tambrey ; WAM R20117* (field tag—439) (juvenile), Mt Herbert ; WAM R45362* (field tag—258) (female) & WAM R45363* (male), Barrow Island (* species = C. pallasotus sp. nov., but maintains status as paratype of C. duricola ).

Diagnosis. A small-bodied (to 59 mm SVL), elongate Ctenotus , nasals in contact, prefrontals in contact or not in contact, 26–29 mid-body scale rows, 20–25 compressed lamellae under toes with narrow callus, usually eight supralabials and supraciliary scales; pattern simple and full including six (occasionally eight) pale narrow longitudinal stripes on a blackish-brown ground color, dorsal stripes not continuing on head to snout, tail not red or blue, absence of upper lateral row of spots between dorsolateral and lateral stripes, dark vertebral stripe continues to anterior-most nuchal or parietal, parietals without blotches or spots, pale dorsolateral stripe continues anteriorly to eye, pale paravertebral stripes join on tail anterior to level of heel of extended hindlimb, lower labial scales variably stippled.

Description. 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 welldeveloped, palmar and plantar surfaces with raised conical to triangular scales with rounded tips, fingers and toes five, finger length: 3>4>2>5>1, toe length: 4>3>2>5>1, digits laterally compressed with obtuse keel, 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), supraciliaries 7–9, loreals two, preoculars two, presuboculars one, supralabials 7–9, infralabials 7–10, upper eyelid with translucent scales, lower eyelid scaly, ear opening D-shaped with 2–6 ear lobules on anterior edge, nuchals 2–7; 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. Variation in continuous and meristic characters is summarized in Table 1.

Coloration. Simple pattern of light to medium blackish-brown background and six (occasionally eight) longitudinal stripes; on lighter specimens, vertebral stripe darker than other areas of background color; four pale dorsal stripes narrow (<½ scale width), interrupted by encroachment of dark dorsal border of scale giving a dashed appearance; two lateral stripes wider (>½ scale width) and solid, continuing forwards to ear and on to upper labials and below eye; paravertebral stripe usually continues anteriorly to eye; short pale lower lateral stripe below upper lateral stripe from below angle of jaw to forelimb; purplish-black eyes somewhat visible through medial supraocular scales; ear lobules pale; lower labials pale with variable stippling; all ventral surfaces pale and immaculate; ground color of legs, arms, and tail light reddish-brown to tan; arm with 4–6 faint alternating light and dark longitudinal stripes; leg with 6–8 contrasting light and dark stripes; on tail, pale paravertebral stripes usually join anterior to the level of the heel of extended leg; distal portion of tail tan on dorsal surface with stripes only on lateral surfaces.

Distribution. Eastern Pilbara region of Western Australia. North and west to near Whim Creek, south to Newman and east to Woodie Woodie mine ( Fig. 4 ).

Habitat. Occurs on rocky slopes with spinifex and associated colluvial surfaces in the Pilbara, including mulga woodlands.

Etymology. The specific name is from the Latin durus, meaning hard, and the suffix -cola, meaning to inhabit, in reference to this species occurrence and presumed preference for the hard surfaces of the Pilbara region.

Remarks. Of the five paratypes listed by Storr (1975), only WAM R12629 from Woodstock in the northern Pilbara is unambiguously a true C. duricola with the clean morphology. The other four specimens we assign to C. pallasotus sp. nov.: WAM R20115 from Tambery possesses the spotted morphology and occur at the eastern limit; WAM R20117 from Mt Herbert also occurs at the eastern limit and shows the spotted morphology (albeit weakly); for the two specimens from Barrow Island, WAM R45362 shows the clean morphology, whereas WAM R45363 has the spotted morphology. This raises the possibility that Barrow Island has both species, or that it only has C. pallasotus sp. nov. but with variable expression of the spotted morphology, similar to the North West Cape populations.

This species is now confined to the eastern Pilbara region. The pattern of allopatric replacement of C. duricola with C. pallasotus sp. nov. within the Pilbara region corresponds to the supposition of Pepper et al. (2013) that the Fortescue River system provides a major biogeographic break within the region that can potentially drive allopatric speciation. Other species that also share similar distributional patterns are Egernia cygnitos vs. E. epsisolus ( Doughty et al. 2011a) , Diplodactylus savagei vs. D. galaxias (Doughty et al. 2010) , and Diporiphora valens vs. D. vescus ( Doughty et al. 2012) . Species distributions, however, do not always fall exactly along the same biogeographic breaks, with each taxon showing idiosyncratic patterns between species along the Fortescue River barrier (see Doughty et al. 2011b; Pepper et al. 2013).

Character piankai (10) rhabdotus sp. nov. (14) duricola (20) pallassotus sp. nov. (18)

SVL 45.6±4.7 53.4±4.6 51.1±3.8 52.1±5.5 (38–53) (44–61) (44–59) (45–65)

RTL 2.3±0.2 2.2±0.2 2.0±0.2 2.1±0.2 (1.9–2.5) (1.9–2.3) (1.6–2.4) (1.7–2.4)

HL 8.8±0.6 10.3±0.7 9.8±0.6 10.0±0.7 (8.0–9.6) (8.9–11.1) (8.3–10.7) (9.0–10.9)

HW 5.3±0.5 6.4±0.6 6.1±0.5 6.3±0.4 (4.7–6.2) (5.1–7.5) (5.1–6.7) (5.6–7.0)

HD 4.3±0.3 5.0±0.5 4.9±0.4 5.2±0.5 (3.8–4.6) (4.2–5.7) (4.2–5.9) (4.1–5.8)

MBSR 23.8±0.6 26.3±0.7 27.4±1.1 27.9±1.2 (22–24) (26–28) (26–29) (26–30)

4ToeL 7.6±0.4 8.5±0.5 8.6±0.7 8.7±0.4 (7.1–8.1) (7.7–9.2) (7.3–9.9) (7.8–9.4)

ToeLam 22.2±1.9 23.3±1.6 23.1±1.8 22.5±1.3 (18–25) (21–26) (20–25) (21–25)

SupLab 8.0±0.0 7.9±0.4 8.0±0.3 8.0±0.2 (8–8) (7–9) (7–9) (7–9)

InfLab 8.0±0.0 8.1±0.7 8.3±0.7 8.1±0.6 (8–8) (7–9) (7–10) (7–10)

Supraciliaries 7.8±0.4 7.9±0.5 7.7±0.5 7.7±0.5 (7–8) (7–9) (7–9) (6–9)

EarLob 3.5±0.6 3.3±0.6 3.7±0.8 3.8±0.7 (3–5) (2–5) (2–6) (2–6)

Figures

FIGURE 2. Photographs in life of Ctenotus duricola senso lato individuals. A) eastern form (clean morphology) — Skull Springs, eastern Pilbara, WA (WAM R 175335; photo: R. J. Ellis); B) eastern form—Gillam Siding, Abydos, WA (photo: B. Maryan); C) western form (spotted morphology) — Juna Downs, Hamersley Range, WA (photo: B. Maryan); D) western form—near Pannawonica, Hamersley Range, 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.