Liopholis purnululu, Aplin & Maryan & Armstrong & Pavey & Donnellan, 2024

Aplin, Ken P., Maryan, Brad, Armstrong, Kyle N., Pavey, Chris R. & Donnellan, Stephen C., 2024, Molecular and morphological assessment of the Liopholis inornata (Rosén, 1905) species group (Reptilia: Squamata: Scincidae), with descriptions of two new species from northern Western Australia, Zootaxa 5551 (2), pp. 299-332 : 322-327

Liopholis purnululu sp. nov.

Purnululu Skink

( Figs 6 , 8 , 10 , 11 )

Holotype. WAM R103112 , female, Bungle Bungle Range, Purnululu National Park (-17.43, 128.4), Western Australia, Australia, collected by N. Gambold, 5 July 1989. Fixed in 10% formalin, stored in 70% ethanol.

Paratypes. Five from Western Australia. WAM R103113–114 , male, female, Bungle Bungle Range, Purnululu National Park (-17.43, 128.4); WAM R156715–716 , WAM R156745 , female, female, male, Bungle Bungle Range , Purnululu National Park (-17.35, 128.62) .

Diagnosis. A moderately robust, small-sized Liopholis (maximum SVL 77 mm), with round pupil, smooth dorsal and caudal scales, relatively short tail, up to 39 midbody scale rows, ≤ 20 fourth toe lamellae and a plain brownish coloration with obscure pattern.

Comparisons with other species. Liopholis purnululu sp. nov. differs from nominate L. inornata from southern semiarid to arid Western Australia, all populations of L. s. slateri , and L. s. virgata in its smaller size (SVL to 77 mm versus to 84 mm, 93 mm and 94 mm, respectively). Liopholis purnululu sp. nov. further differs from L. inornata and L. s. slateri by having lower paravertebral scale and subdigital lamellae counts ( Table 5 ) and having less dense, dark pigmentation on the flanks and back ( Fig. 6 ). Liopholis purnululu sp. nov. further differs from L. s. virgata by lacking a black vertebral stripe ( Fig. 6 ). Dorsal colour in L. inornata and L. parva sp. nov. (see above) tends to be yellowish to reddish or orange-brown rather than brownish as in L. purnululu sp. nov. ( Fig. 6 ). Liopholis parva sp. nov. further differs by having an even smaller size (SVL to 66 mm versus to 77 mm) and proportionally shorter neck and head (the latter caused by a short snout). The geographically closest congener to L. purnululu sp. nov. is L. striata which attains a much larger size (SVL to 112 mm), has a predominately reddish-brown (versus brownish) colour, fewer subdigital lamellae (16‒19 versus 19‒20), higher paravertebral scale counts (55 or more versus 46‒ 48), higher midbody scale counts (40‒43 versus 38‒39) and a vertically ovate rather than rounded pupil.

Details of holotype. ( Fig. 10A ). SVL 77.1; TL 90; HD 10.9; HL 18.0; HW 13.8; HNL 29.5; FLL 22.6; HLL 28.1; AGL 36.2; MBS 38; PV 46; SDL 19; nasals widely separated; prefrontals in broad contact; supraciliaries 6/7, fused to second loreal on left side; nuchals 1/1; upper palpebrals 11/11; primary temporal single; enlarged upper secondary temporals 1/1, each with one adjacent smaller temporal bordering the parietal; supralabials 7/7; ear lobules 4/4, uppermost lobule largest in series.

Description. See Table 5 for summary statistics of mensural and meristic data and Supplementary Table S1 for measurements and counts of individual specimens. Fig. 6 shows WAM R156716 compared to a selection of other Liopholis species and Fig. 10B shows the same individual photographed in life. Head and details of scalation are illustrated in Fig. 8 .

Head moderately deep, barely distinct from neck; external ear opening prominent, narrow and much higher than wide; snout very short, rounded in profile and slightly angular in lateral view; body moderately robust, round in cross-section with flat venter and well-developed, thickset pentadactyl limbs; digits moderately long and slender; claws strong with long sharp tip; tail round in cross-section gradually tapering to pointed tip. Nasals widely separated; groove representing nasal-postnasal suture discernible but weak; two loreals, mostly equal or second usually a little higher than wide, fused to first supraciliary on left side (e.g. WAM R103112, WAM R156715); two presuboculars, first higher than second; prefrontals in broad contact; frontal much wider anteriorly, tapering gradually to a rounded point, equal or only slightly wider than interparietal; frontoparietals paired; parietals bordered posteriorly by an enlarged nuchal scale and laterally by two temporal scales; 3‒5 ear lobules, small and obtuse, mostly equal in size or decreasing slightly in size downwards; 6‒8 (mostly 7) supraciliaries, first three larger and decreasing in size to slightly larger last scale; five supraoculars, second much larger and fifth smallest with anterior two in contact with frontal; 9‒12 upper palpebrals; one nuchal on each side; seven supralabials with the fifth and sixth subocular, subocular supralabials separated from granular eyelid scales by a row of small scales; first pair of chin shields in broad contact, second pair typically separated medially by one scale or three scales (e.g. WAM R103114), third pair longitudinally divided, in contact (e.g. WAM R156716) or separated medially by one or two scales; 38‒39 midbody scale rows; 46‒48 paravertebral scales; 19‒20 lamellae under fourth toe, with an apical series of weak or strong calli, outer edges denticulate, palmar and plantar scales small and ovate.

Colour in life. Colour in life is based on illustrated figures and field observations of live individuals. Dorsal surface pale brown, head slightly paler. Many dorsal scales with outer edge bearing a faint darker brown smudge, forming very indistinct longitudinal lines, more pronounced in one darker specimen (e.g. WAM R156745). Lateral surface uniform pale grey or with some faint indication of cream posterior edging becoming more distinct above hindlimb. Some specimens (e.g. WAM R156715, WAM R156745) have some dark lateral edges of scales forming obscure streaks that are more distinct between ear and forelimb. Tail concolorous with dorsal surface, with cream posterior edge on many scales forming an obscure transverse alignment of narrow bands. Upper surface of limbs pale brown with no discernible markings. Posterior supralabials and sometimes infralabials with diffuse darker brown smudge on anterior edge of fourth to seventh supralabial. Ventral surface creamy white. Claws with dark culmen on upper surface.

Etymology. After the regional name in the Aboriginal Kija language for the sandstone of the Bungle Bungle Range, and with the aim of drawing attention to the biological endemism of this significant landform in the southeast Kimberley ( Gambold 1992). Used as a noun in apposition.

Distribution. Apparently restricted to the Bungle Bungle Range in the southeast Kimberley, a heavily dissected sandstone plateau, partly bounded by cliffs and cut by numerous gorges, which is surrounded by an extensive sandplain ( Hoatson et al. 1997). It is possible that the plateau of the Bungle Bungle Range within the Purnululu National Park comprises its total distribution.

Biological surveys conducted in the Purnululu National Park to date have not recorded any other species of Liopholis ( Gambold 1992, T. Partridge, pers. comm.). Based on collection records ( Atlas of Living Australia 2024), L. purnululu sp. nov. is widely allopatric to any other Liopholis species. The geographically nearest congener, L. striata , has been recorded approximately 300 km to the south in the vicinity of Billiluna on the western edge of the Tanami Desert ( Storr et al. 1999).

Habitat, ecology and conservation. Menkhorst & Cowie (1992) provide a detailed description of the habitat where individuals were either pit-trapped or excavated from burrows on sandy loams of the Elder Uplands of the Bungle Bungle Range plateau ( Fig. 11 ). Their account describes a low and sparse tree layer, dominated by Corymbia cliftoniana (Fitzgerald) with occasional C. collina (Fitzgerald) , and with a canopy height of 4–8 metres. Corymbia dichromophloia (Mueller) occurs on rocky slopes and Eucalyptus cupularis Gardner is restricted to the sandy ephemeral watercourses. The shrub layer is well developed, particularly along drainage lines and includes Acacia gonocarpa Mueller , A. stipuligera Mueller , A. tumida Mueller , A. lycopodiifolia Hook , Grevillea miniata Fitzgerald , G. refracta Brown and Jacksonia odontoclada Mueller. Triodia spicata Burbidge forms a dense ground layer with T. microstachya Brown forming large hummocks on the sandy banks of ephemeral watercourses. This vegetation community recorded the highest percentage cover of shrubs and hummock grasses, and no introduced plants were detected ( Menkhorst & Cowie 1992).

The ecology of this species is largely unknown. The limited field observations of L. purnululu sp. nov. in a small area on the Bungle Bungle Range plateau indicate that this species is numerous, with conspicuous multi-entranced burrows positioned at the base of Triodia clumps on shallow sandy soils ( Gambold 1992, B. Maryan & R. Browne-Cooper, pers. obs., Fig. 11 ).

The species has a potentially restricted geographic distribution on the largely inaccessible Bungle Bungle Range plateau (450 km 2) that is protected within the Purnululu National Park (2,397 km 2). The national park is also a UNESCO World Heritage Site recognised for its universal value criteria of containing areas of natural and geological significance. Despite this level of protection, caution is certainly warranted considering the conservation status of the closely related L. kintorei and L. s. slateri in which populations of both species have declined significantly in recent decades ( McAlpin 2001; Pavey 2004, 2007; Moore et al. 2015). Furthermore, as highlighted by Gambold (1992), optimum fire regimes for this species have not been defined, and further survey effort is required to refine distributional knowledge including the extensive sandplain surrounding the Bungle Bungle Range. Importantly, no feral herbivores or predators, particularly cats have been recorded on the plateau, the latter tending to be uncommon but widespread, and occasionally trapped and removed by rangers around camps ( Woinarski et al. 1992).

Available knowledge indicates this species is restricted to the Bungle Bungle Range plateau. The extent of rocky terrain affects the amount of suitable habitat for this burrow-digging species that to date has only been found on sandy loams of the Elder Uplands. Based on existing collection records (N = 6, Atlas of Living Australia 2024) and limited field observations from only two locations, we calculated the extent of occurrence (EOO; minimum convex hull) and area of occupancy (AOO; 2 x 2 km grid cells) of L. purnululu sp. nov. in GeoCat (https;//geocat.kew. org; Bachman et al. 2011). Due to only two occurrence location points, GeoCat cannot create a minimum convex polygon, and hence the EOO, as per IUCN guidelines, must be made identical to the AOO value, which is very small at 8 km 2. Targeted biological surveys on the Bungle Bungle Range in suitable habitat for this species would improve the accuracy of these estimates. Current distributional knowledge of L. purnululu sp. nov. allows for an IUCN listing assessment under criterion B2 of geographic range (AOO <10 km 2) and B(a) number of locations (<5) that qualifies this species for Critically Endangered or at the very least Endangered, under IUCN guidelines and criteria ( IUCN 2022). Ascertaining further conditions under criterion B in relation to population decline are unknown. Further consideration is that without any detailed knowledge of the species’ ecology, life history, distribution and threats to effectively assess the species, it may also be considered as Data Deficient.

Remarks. The description of L. purnululu sp. nov. raises the number of reptile species endemic to Purnululu National Park and the adjacent Osmond Range to three. The other endemics are the gecko, Gehyra ipsa Horner and the skink, Lerista bunglebungle Storr , which is only known from three specimens (e.g. Lloyd 2015). Purnululu National Park is also the type locality for the skink Ctenotus vagus Horner. All the above taxa including L. purnululu sp. nov. were collected during a single biological survey ( Gambold 1992). An emerging pattern in areas of the Kimberley with distinctive underlying geology is that they support several endemic reptile species, particularly geckos ( Laver et al. 2017; Oliver et al. 2017, 2020).

Figures

FIGURE 6. Selection of Liopholis inornata species group specimens illustrating variation in colour and pattern. A) L. inornata WAM R166716, Tropicana Mine, Western Australia, B) L. inornata WAM R163368, Neale Junction Nature Reserve, Western Australia, C) L. inornata WAM R78798, 19 km ENE of Toomey Hills, Western Australia, D) L. inornata WAM R65835, 3 km NE of Comet Vale, Western Australia, E) L. parva sp. nov. holotype WAM R156452, Learmonth Air Weapons Range, Western Australia, F) L. purnululu sp. nov. paratype WAM R156716, Purnululu National Park, Western Australia, G) L. s. slateri holotype WAM R29130, Alice Springs, Northern Territory, and H) L. s. virgata SAM R48873, Neales Camp No. 1, South Australia (photos A‒G: B. Maryan, H: C. Kovach).

FIGURE 8. Lateral and dorsal views of head scalation of A‒B) L. parva sp. nov. holotype WAM R156452, and C‒D) L. purnululu sp. nov. holotype WAM R103112.

FIGURE 10. Liopholis purnululu sp. nov. A) Preserved holotype WAM R103112 in dorsal, ventral and lateral views, and B) adult paratype WAM R156716 from the Bungle Bungle Range, Purnululu National Park, Western Australia, photographed in life (photos B. Maryan).

FIGURE 11. A) The habitat of L. purnululu sp. nov., dense Triodia on shallow sandy soils along edge of ephemeral watercourse, Bungle Bungle Range, Purnululu National Park, Western Australia, and B) L. purnululu sp. nov. photographed in situ outside burrow (photos A: B. Maryan, B: N. Gambold).