Diplodactylus galaxias, Doughty, Paul, Pepper, Mitzy & Keogh, Scott, 2010

Doughty, Paul, Pepper, Mitzy & Keogh, Scott, 2010, Morphological and molecular assessment of the Diplodactylus savagei species complex in the Pilbara region, Western Australia, with a description of a new species, Zootaxa 2393, pp. 33-45 : 40-43

Diplodactylus galaxias sp. nov.

Northern Pilbara Beak-faced Gecko ( Figs. 2 , 3 , 5 )

Holotype. R113624, an adult female collected 42km NNE Munjina Roadhouse, Western Australia, Australia (2159’S; 11845’E) on 15 April 1992 by B. Bush.

Paratypes. R146616 (female) – 203 km S Port Hedland, Western Australia, Australia; R158145 (male) – 24.5 km N Cowra Line Camp, Western Australia, Australia; R165134 (male) – 2.6 km WNW Python Pool, Western Australia, Australia; R165502, R165516 and R165532 (males) – West Intercourse Island, Western Australia, Australia; R166639 (female) – Mons Cupri Mine, Western Australia, Australia.

Diagnosis. Differentiated from D. savagei in having smaller body size (means: galaxias – 3 38.1 mm, Ƥ 43.8 mm; savagei – 3 40.0 mm, Ƥ 46.2 mm), less gabled dorsal scales, longer ( galaxias – 17.9 mm; savagei – 16.8 mm) and thinner ( galaxias – 5.0 mm; savagei – 5.2 mm) tail, scattered fine spots (not heavy spots that form transverse rows) on lighter reddish-brown background colour, pale dorsal border to dark loreal stripe and gradual dorsal-ventral colouration transition (not abrupt or marked by spots or stippling).

Description. Small-bodied Diplodactylus with cylindrical body shape and a small, depressed head; tail cylindrical, slightly increasing in width towards tip until about four-fifths of length, then tapering at roughly a 60° angle to tip. Eyes small with no spiny ridges on upper eyelid; snout relatively long and pointed with blunt tip. Scales contacting nostril: supranasal and 6 postnasals; rostral roughly hexagonal without crease, bordered by enlarged supralabials, supranasals and internarials; other than first, enlarged supralabials absent with scales along upper jaw similar in size to adjoining rows of scales; mental wider than long with adjacent enlarged gular scales in 2–3 rows; no enlarged infralabials scales with typical-sized scales along lower jaw; ear aperature small and located near retroarticular process.

Limbs slender and of moderate length; undersurfaces of digits terminating with claw between moderately enlarged apical plates and 6–9 rows of enlarged paired lamellae along length of digit until decreasing to the size of tubercles on palmar and plantar surfaces.

Scales on body small; dorsal and ventral scales approximately the same size. Dorsal scales low, apex not prominent and located at centre of scale. Caudal scales on original tail enlarged and flattened, tending to form transverse rows; scattered enlarged scales on tail tip.

Colouration. In life, dorsum reddish with fine (1–5 scales) pale yellowish spots scattered (not typically forming transverse rows); spots continue to limbs; dark loreal-temporal streak through eye and weakly connecting on nape; a pale border dorsal to loreal streak; top of head slightly pale compared to rest of dorsal colouration. Transition from dorsal to ventral colouration gradual (not demarcated by sharp transition or stippling). Ventral surfaces pale off-white. In preservative, ground colour faded, pale cap on head more prominent and spots creamy white (almost no trace of yellow colour).

Measurements of holotype. SVL—46; TrunkL—23.9; TailL—18; TailW—4.9; ArmL—5.9; LegL—6.4; HeadL—.2; HeadW—6.4; HeadD—3.8; INar—1.0; IO—3.4; IntNar—2; PostNas—6; MentL/ W—0.58; 4FLam—6; 4TLam—8.

Variation. Table 1 presents the ranges of values for the characters measured. Males possess an average of 8 enlarged pointed cloacal spurs on either side of cloaca. Females attain larger body sizes and trunk lengths than males ( Table 1 ). Ground colour showed some limited variation. In some individuals the spotting shows a weak tendency to form rows instead of widely scattered spots (e.g., moderate in R165532 and more pronounced in R165134); some individuals have spots with darker borders that contrast with background colour (e.g., R 110149, R 160861); spotting on the limbs is also variable but tends to be much weaker than on dorsum ( Fig. 3 ).

Habitat. Diplodactylus galaxias is associated with stony hills with spinifex, Eucalyptus and Acacia spp. Individuals shelter in Spinifex clumps and under rocks.

Distribution. Pilbara region ( Fig. 1 ): along the coast from the mouth of the Fortescue River east to the Burrup Peninsula and slightly inland to Whim Creek; west to Peedamulla Station and vicinity of Pannawonica then extending east and inland along the Chichester Range (not occurring south of the Fortescue River) to the headwaters of the Western Shaw River. Also known from West Intercourse Island in the Dampier Archipelago.

Etymology. galaxias (Greek) is in reference to the widely-scattered spots on the dorsum which resemble stars in a galaxy. Used as a noun in apposition.

Comparison with D. savagei . Diplodactylus galaxias can be distinguished from D. savagei by the spots being finer and never tightly aligning to form transverse bars. Some individuals of D. galaxias have the fine spots in weak rows, but the spots remain widely separated; this is in contrast to the transverse rows in D. savagei that are formed by rows of heavier spots in contact that usually form solid bars ( Figs. 2 , 3 ). Furthermore, along the ventrolateral zone the transition from the dorsal to ventral colouration is very gradual in D. galaxia s, whereas it is abrupt in D. savagei . In D. savagei , the lateral zone also tends to have small spots or fine stippling where the dorsal and ventral colouration meet. Diplodactylus galaxias has a smaller mean and maximum body size than D. savagei and a longer and thinner tail ( Table 1 ). The shape of the dorsal scales also differs subtly, with D. galaxias having quite low scales whereas D. savagei has more gabled scales with the apex towards the posterior edge of the scale.

Figures

FIGURE 1. Distribution of Diplodactylus savagei populations in the Pilbara and Ashburton regions of Western Australia. Key: blue circles— D. savagei; red circles— D. galaxias sp. nov.; stars—genotyped individuals.

FIGURE 2. Photographs of live Diplodactylus galaxias sp. nov. (above) from the Burrup Peninsula and D. savagei (below) from near the type locality. Photographs – B. Maryan.

FIGURE 3. Variation of dorsal pattern within Diplodactylus galaxias sp. nov. (top row) and D. savagei (bottom row).

FIGURE 5. Holotype of Diplodactylus galaxias sp. nov. (WAM R 113624, an adult female). Photograph – B. Bush.