Liopholis margaretae (Storr 1968)

MacDonnell Ranges Rock Skink

(Figures 5E–F)

Holotype. WAM R29129, adult male, collected by K.R. Slater and D.A. Lindner on 25 November 1964 from Palm Valley, Northern Territory (-24.05, 132.7). Measurements in millimetres: SVL 107.5, tail 171 (original, 159% of SVL), HL 20.2, HW 16.8, HD 10.9, AGL 50.5, BW 22, FLL 26, HLL 37.8. Scale counts: MSR 36, SubDig 26, SupLab 8, SupCil 8, Cil 11, Lob 4 (with an additional 5 th miniscule uppermost lobule), one pair of nuchal scales. This specimen exhibits the well-patterned morph, and colouration is typical of the species in preservative.

Diagnosis. Liopholis margaretae can be distinguished from other Liopholis by a combination of the following characters: moderately large size (maximum SVL up to 108.5 mm); snout relatively pointed—distance between outer edges of parietals usually no more than the distance from the snout to the posterior edge of the frontal; dorsal scales smooth; conspicuous black callus along free edge of subdigital lamellae; palmar and plantar scales each with a prominent black tubercle; usually eight supraciliary scales; usually three enlarged lobules projecting from anterior border of ear opening; midbody scales in 38 or fewer rows. Dull olive or greyish brown posteriorly, grading into reddish-brown anteriorly; ventral surface uniform creamish-white. Two morphs occur: one well-patterned with mostly obscure black markings and scattered white spots, one virtually patternless (Figure 5E–F).

Description. Full summary statistics of morphology data are presented in Table 1. A moderately large, robust Liopholis species. Measurements (as means with range in parentheses): SVL 94.1 mm (52.2–108.5); HL 19.7 mm (12.6–22.2); HW 14.8 mm (8.5–18.3); HD 10.5 mm (6–13.5); AGL 48.4 mm (25.1–58.4); BW 18.5 mm (10–24.2); FLL 24.9 mm (16.6–28.8); HLL 34.7 mm (21.7–40.3). The original tail length (TL) of adults (> 75 mm SVL) is 168.7 mm (152–187.5), which is 173% (158%–190%) of SVL.

Head. Head dorsoventrally depressed (head depth is 47%–62% of head length, x̄ = 53%). Snout relatively pointed (head length is 120%–149% of head width, x̄ = 134%) and relatively shallow. Supralabials 8–9 (usually 8); supraciliaries 6–9 (usually 8); ciliaries 9–13 (usually 11); ear opening large, oblong and oriented vertically, with 3–4 (usually 3) enlarged lobules on the anterior margin, projecting over opening, often with a single additional tiny ear lobule above the enlarged series, ear lobule shape is variable, being either obtuse, rectangular or acute; only one pair of enlarged nuchal scales; nasal scales separated, moderately to widely so; post-narial groove absent; prefrontals in broad contact, occasionally in narrow contact or narrow separation; neck only slightly narrower than widest part of head (above tympani); lower eyelid movable; parietal scales divided.

Body. Moderately robust (axilla-groin length is 47%–56% of SVL, x̄ = 51%) with smooth, overlapping scales in 33–38 rows (MSR), but usually 34–36 (rarely 33, 37 and 38).

Limbs. Limbs of moderate length (forelimb is 23%–32% of SVL, x̄ = 27%; hindlimb is 25%–44% of SVL, x̄ = 37%); digits short and well-developed; finger length: 4>3>2>5>1, toe length: 4>3>5>2>1; subdigital lamellae 20–28 (usually 24) under fourth toe, with conspicuous black callus along free edge of lamellae; claws sharp and recurved; palmar and plantar scales each with prominent black callus along free edge.

Tail. Original tail long (140%–190% of SVL, x̄ = 169%; n = 10) and approximately cylindrical, tapering to a pointed tip.

Colour pattern in life (Figures 5E–F). Background colouration of the dorsal and lateral surfaces of the body, limbs and tail typically dull olive or greyish brown posteriorly, grading into reddish-brown anteriorly. Ciliary scales bright yellow; ear lobules pale cream; ventral surfaces uniform creamish-white; chin and throat orange. Two colour morphs occur: well-patterned specimens have prominent black markings on back and tail, irregularly distributed or tending to align longitudinally; lateral surfaces with black spots which tend to align in oblique rows directed up and back, sometimes only anteriorly and vaguely so; white spots are present on dorsum, flanks and limbs, sometimes forming transverse rows on flanks; irregular black markings on top and sides of head, typically on scale margins and sometimes forming barring on the lips; black streak running from around the loreal region, through eye and extending onto the secondary temporals; irregular pale spots may be present in labial region; sutures of chin scales irregularly marked in black or dark brown; sometimes with dark spots or short dark lines on throat. The patterning of plain specimens typically consists of no more than faint dark edges to dorsal scales, which may give the appearance of narrow longitudinal lines; some plain specimens have few scattered white lateral spots, and a black streak anterior and posterior of the eye. Tail and limb colour patterning is generally similar to that of the dorsum and flanks.

Colour pattern in preservative: Colour pattern in preservative is largely similar to the description in life but with slightly to significantly faded and less vibrant colouration overall. The orange chin and throat colour (present in live specimens) is absent in all preserved specimens. The characteristic black calli of the subdigital lamellae, plantar and palmar scales is substantially faded or absent in preservative.

Distribution and habitat. The distribution of Liopholis margaretae falls almost entirely within the MacDonnell Ranges bioregion (Thackway & Cresswell 1995) of the Northern Territory, Australia (Figure 7), where it occurs widely across the region on mountain ranges comprising a range of sedimentary and metamorphic geology types. Also recorded (but much less widespread) in adjacent ranges of the Burt Plain and Finke bioregions. It is recorded as far north as Nanga Range, and as far south as Henbury Station. It shelters in burrows in soil beneath large rock slabs, or in deep rock crevices.

Conservation status. In the most recent (2017) conservation assessment of L. margaretae it was assessed as Least Concern on the IUCN Red List (Fenner et al. 2018); however, that assessment is now outdated given it included in its area calculations both the South Australia populations now attributed to L. aputja sp. nov. in the Mann-Musgrave Ranges and L. personata (formerly a subspecies of L. margaretae) in the Flinders Ranges. The updated AOO is c. 25,600 km 2 (i.e. the area of rugged habitat in the MacDonnell Ranges bioregion, and adjacent ranges) and EOO is c. 112,200 km 2 (i.e. the area of a minimum convex polygon encompassing the rugged habitat used for AOO). These values indicate a large distribution (Figure 9)—i.e. they exceed geographic range thresholds for consideration under Criterion B of the IUCN Red List. At present there are no robust data on abundance, population trends, or threats. Much of the species’ range includes protected areas (e.g. Watarrka NP, Finke Gorge NP, Tjoritja / West MacDonnell Ranges NP, Owen Springs Reserve). However, in the absence of additional data, the species will most likely remain as Least Concern.

Remarks. Currently used common names for L. margaretae include Centralian Ranges Rock-skink (Cogger 2014; Jolly et al. 2023; ASH 2023) or Central Ranges Rock Skink (Wilson & Swan 2021). These names are now misleading given that L. margaretae sensu stricto does not occur in the Central Ranges bioregion—rather, L. aputja sp. nov. is endemic to this bioregion. We therefore suggest the common name MacDonnell Ranges Rock Skink for L. margaretae, given this species is almost entirely confined to the MacDonnell Ranges bioregion. There are 17 other vertebrate taxa endemic to the MacDonnell Ranges (McDonald et al. 2021).