Gehyra montium Storr, 1982

Hutchinson, Mark N., Sistrom, Mark J., Donnellan, Stephen C. & Hutchinson, Rhonda G., 2014, Taxonomic revision of the Australian arid zone lizards Gehyra variegata and G. montium (Squamata, Gekkonidae) with description of three new species, Zootaxa 3814 (2), pp. 221-241 : 233-235

Gehyra montium Storr, 1982

Figs 3 , 8 .

Gehyra montium Storr, 1982: p. 56 . Holotype: WAM R31732, from Mt Lindsay [Watarru], Birksgate Range , north-western South Australia (27º 02’S, 129º 53’E).

Specimens scored for morphology (n=29; all genotyped as ‘montium clade’): SAMA: R 44368– 69, 14 km ENE Mt Cooparinna , SA (26º 20’S, 130º 06’E) , R 44407, 8.4 km NW Mt Kintore , SA (26º 30’S, 130º 26’E) , R 46107, 21 km ENE Pipalyatjara , SA (26º 07’S, 129º 22’E) , R 46134– 36, 16 km E Pipalyatjara , SA (26º 10’S, 129º 33’E) , R 46139, 40 km NE Pipalyatjara , SA (25º 59’S, 129º 29’E) , R 46168, 26 km S Pipalyatjara , SA (26º 24’S, 129º 08’E) , R 48718, 4 km W Mt Lindsay , SA (27º 02’S, 129º 50’E) , R48731–33 , Mount Lindsay , SA (27º 02’S, 129º 53’E) , R56451, R56497, 5.6 km W Mount Hoare , SA (27º 03’S, 129º 39’E) , R61922–24 K, Morgan Range , WA (25º 53’S, 128º 23’E) . WAM: R 90848, Woodstock Station , WA (21º 37’S, 119º 01’E) , R 90903, Woodstock homestead, WA (21º 37’S, 118º 57’E) , R 98094, Warburton , WA (26º 08’S, 126º 34’E) , R 125475, 30km E Newman , WA (23º 19’S, 120º 02’E) , R132553 , De Grey River Station , WA (20º 16’S, 119º 12’E) , R154518 , R154523 , 156679 , Yarri Mining Camp , WA (20º 36’S, 120º 19’E) , R156317 , Chichester Range , WA (22º 14’S, 118º 58’E , R166317 , R166321 , Morgan Range, WA (25º 53’S, 128º 23’E).

Diagnosis. Distinguished from other Australian Gehyra by a combination of modally seven divided scansors under the expanded portion of the fourth toe, small to moderate size, generally two pairs of enlarged chin shields, second infralabial notched, a dorsal colour pattern combining pinkish brown to rufous colouring (in life) usually patterned by small pale spots interspersed in a continuous network of irregular, dark lines, and a karyotype of 2n=42a (illustrated in King 1979, fig. 9; Moritz 1986, fig. 3). Distinguished from some other rock dwelling species ( G. minuta , G. moritzi sp. nov. and G. pulingka sp. nov.) by more reticulate dorsal pattern and often weak contrast of pale spots. Most similar to G. variegata and G. versicolor sp. nov. but somewhat smaller and usually more rufous in colouring with dorsal white markings consisting of small poorly contrasting dots (readily lost in preservative) that are not consistently coordinated with the dark markings.

This diagnosis applies to populations of Gehyra genetically assignable to the “ montium clade” of Sistrom et al. (2013).

Description. Adult snout-vent length 36–51 mm (mean = 41.7 mm, n = 29). Length of original tail 41–58 mm (mean = 113% SVL, n = 9).

Nostril bordered by rostral, first supralabial, supranasal and two post nasals, the upper usually markedly larger than the lower. None to three (modally 1) moderate internasal scales separate the supranasals above the rostral. Supralabials 8–11 (mode 8). Infralabials 7–9 (mode 8). Consistently two pairs of chin shields, anterior pair in contact with only the first infralabial. Chin shields separated from the third and succeeding infralabials by the interpolation of a series of enlarged scales (parinfralabials) that margin the ventral edge of the infralabials. Second infralabial notched where this parinfralabial scale row starts. Scansors under pad of fourth toe divided, 7–8 (mode 7). Precloacal pores in males 10–13, (mean = 11.3, n = 16).

The karyotype is 2n=42a, a karyotype that is shared with a number of Gehyra species , including G. minuta and some populations that are morphologically distinct from G. montium ( King 1979, fig. 13a) and currently assigned to G. punctata (Fry, 1914) in Western Australia.

In life, dorsally light grey-brown to reddish brown to pinkish, the entire dorsal surface patterned by a strong to weak reticulum of blackish grey ( Fig. 8 ). Scattered over the dorsal surface are small circular pale spots, often only contrasting weakly with the dorsal background colour. In preservative any rusty colour tones and pale spots tend to disappear leaving the specimens greyish with a dark reticulum.

Distribution. The western portion of the Australian arid zone, from the north-west of South Australia, and south-east of the Northern Territory, north-west to the Pilbara Region of Western Australia.

Comments. Throughout arid areas of central and northern Australia, rocky outcrops may harbour relatively small Gehyra species , typically with rufous colouring and a pattern including pale spots. The name G. montium has often been applied to many such populations, but our study reveals that this species only just extends east of the Western Australian border, to the Tomkinson Ranges and Birksgate Ranges (east to Mt Kintore) in South Australia and is probably restricted in the Northern Territory to the far south-west corner (Uluru and the Petermann Ranges). The fact that the species was not recognised hitherto as extending westward as far as the Pilbara possibly reflects a tacit assumption that G. montium was a central Australian species, as well as the similarity of colour pattern in preserved G. montium and G. variegata . This similarity is such that individuals of the two species will continue to be difficult to separate by morphology alone

In the adjacent rocky ranges of north-west South Australia and the southern and central Northern Territory, G. montium is replaced by geckos of Clades 2 and 1 ( Sistrom et al. 2013), respectively, and these are described below as new species.

Populations we have assigned to this species require further study in several areas. Colour and pattern as described here is based on central Australian populations for which we had freshly collected material of known genotype; preserved specimens examined by us suggest that this colour pattern extends to Pilbara populations, but in this region the species is more variable in colour pattern. Animals of known genotype from this area include not only animals with a dark dorsal network, but also almost plain individuals, grey in preservative but possibly rusty in life, with no more than scattered small black speckles. Three specimens genotyped as G. montium by Sistrom et al. (2013) are from areas to the south and west of the species’ main distribution, apparently in areas of sandy desert rather than rocky ranges. Further collection and typing of specimens from these populations is needed to confirm that these seemingly atypical records are correctly documented, and that there are populations of Gehyra from these areas that pertain to this species.

When describing this species Storr (1982) suggested it might represent the 2n=38 karyotypic group of King (1979). However, the data of Moritz and our own checks of karyotype show that populations conspecific with the type population of montium have the 2n=42a karyotype.

Figures

FIGURE 3. Distribution of the species of the Gehyra montium - variegata complex, based on populations identified from DNA sequences. Inset shows the detailed distributions of species in the Central Ranges area.

FIGURE 8. Gehyra montium Storr, 1982. A. Adult male, SAMA R61924, from Morgan Range, Western Australia. B. Adult female (not collected) from Uluru, Northern Territory. Note reticulate dark markings, reddish body colour and small, weakly contrasting pale spots that do not margin the dark markings.