Lerista munuwajarlu, Zimny & Vanderduys & Kemp & Zozaya, 2025

Zimny, Anders, Vanderduys, Eric, Kemp, Jeanette E. & Zozaya, Stephen M., 2025, Scratching the surface of the Gulf Coastal Bioregion: Lerista munuwajarlu sp. nov. (Scincidae; Sphenomorphini), a new fossorial skink from the Northern Territory, Australia, Zootaxa 5647 (6), pp. 526-540 : 532-535

Lerista munuwajarlu sp. nov.

Gulf Coastal Slider

urn:lsid:zoobank.org:act:B5795CA7-E152-4796-8139-9C1A521613ED

( Figs. 3–5 )

Holotype. MAGNT R39264 (field no. SMZ2665), Pungalina-Seven Emu Sanctuary, NT (16° 22'34.6"S, 137° 35'42.7"E), collected 10 September 2022 by N.E. Laven, A. Zimny, S.M. Zozaya, & S.A. Macor . Paratype. MAGNT R37167 , Pungalina-Seven Emu Sanctuary, NT (16° 22'36.7"S, 137° 35'46.7"E), collected 30 June 2012 by A. Zimny, E. Vanderduys, J. Perry, & G. Perkins .

Diagnosis. Distinguished from all other Lerista by the unique combination of the following characters: 18 midbody scale rows; lower eyelid moveable; no trace of forelimbs; distinct interparietal and frontoparietals; prefrontals present; three supraoculars; four supraciliaries in a continuous row; two loreals; and the possession of a broad, dark upper lateral stripe.

Etymology. Munuwajarlu [moon-oo-wah-jar-loo] derives from the Garrwa words munuwa meaning “no” and jarlu meaning “arm”, aptly describing the lizard as having no arms. The name is treated as an indeclinable noun in apposition. The species is traditionally known and was named by Elders of the Garrwa People, whose traditional lands extend from east of the McArthur River at Borroloola, NT, to Doomadgee and the Nicholson River, Qld. Pungalina-Seven Emu Sanctuary sits within the traditional lands of the Garrwa. The name is used with permission from Peggy and Daphne Mawson, fluent speakers of Garrwa language and Traditional Owners of Jinningina (Spring Creek), a neighbouring property to Robinson River. We recommend ‘Gulf Coastal Slider’ as the common name, which refers to the species so far being known only from the Gulf Coastal Bioregion.

Description of holotype (MAGNT R39264). Adult with free lower eyelid; ear minute; front limb absent; hindlimb didactyl; prefrontal present; frontoparietals and interparietal free; frontal contacts frontonasal, prefrontal, first and second supraocular, frontoparietal, and interparietal; supraoculars three; supraciliaries four in a continuous row; loreals two; preocular one; presubocular present; postocular present; supralabials five with majority of third below eye; postsupralabial single; pretemporal single; primary temporal contacts fourth and fifth supralabial, postocular, pretemporal, parietal, and upper and lower secondary temporal; infralabials five, two contacting postmental; enlarged chin shields in three pairs; enlarged nuchal scales four, with first row fused with upper secondary temporals; midbody scale rows 18; paravertebral scale rows 103; enlarged preanals two; subcaudals 83. Measurements and proportions (mm). EE = 2.3, 51% HL; EN = 1.8, 40% HL; EyL = 0.8, 18% HL; FL = 1.5; FnL = 0.6, 38% FnW; FnW = 1.6; FW = 1.7, 113% FL; HL = 4.5, 7.1% SVL; HLL = 4.4, 7.0% SVL; HW = 4.0, 89% HL; IL = 1.1; IN = 1.0, 22% HL; IW = 1.3, 118% IL; MbW = 5.0, 7.9% SVL; MV = 1.1, 92% PV; NaL = 0.1, 14% NsL; NsC = 0.2, 29% NsL; NsL = 0.7, 16% HL; PoML = 1.0, 67% PoMW; PoMW = 1.5; PV = 1.2; RF = 1.5, 33% HL; RL = 0.6, 13% HL; SE = 1.1, 24% HL; SVL = 63.1; TaL (original) = 59.0, 94% SVL.

Description of paratype (MAGNT R37167). Description as for holotype (MAGNT R39264) except with first row of nuchals not fused with upper secondary temporals, paravertebral scale rows 88, and subcaudals 76. Measurements and proportions (mm). EE = 2.3, 50% HL; EN = 1.5, 33% HL; EyL = 0.8, 17% HL; FL = 1.5; FnL = 0.6, 40% FnW; FnW = 1.5; FW = 1.4, 93% FL; HL = 4.6, 7.7% SVL; HLL = 4.9, 8.2% SVL; HW = 4.0, 87% HL; IL = 1.2; IN = 1.1, 37% HL; IW = 0.9, 75% IL; MbW = 4.8, 8.0% SVL; MV = 0.8, 73% PV; NaL = 0.2, 25% NsL; NsC = 0.3, 38% NsL; NsL = 0.8, 17% HL; PoML = 0.8, 62% PoMW; PoMW = 1.3; PV = 1.1; RF = 1.4, 30% HL; RL = 0.6, 13% HL; SE = 1.2, 26% HL; SVL = 60.0; TaL (original) = 51.6, 86% SVL.

Colour and pattern in preservative. Dorsum of head, body and tail creamy beige to greyish-brown. Head mottled with dark flecks. Body with thin brown streaks forming four narrow longitudinal stripes on paravertebral and laterodorsal scale rows, extending from nuchals to tail. Paravertebral stripes continue along tail almost to tailtip; laterodorsal stripes merge into broader upper lateral stripe at base and side of tail. Paravertebral stripes more pronounced and slightly darker. Flanks with broad (one scale width), bold dark-brown upper lateral stripe running from nasal, through eye, alongside tail, fading gradually before breaking into streaks on the distal tail; on body, this stripe covers the lower half of scale row three and the upper half of scale row four. Lower lateral and ventral surfaces are creamy beige and patternless, except for original tail, which shows scattered dark-brown spots, predominantly ventrally. Hindlimbs are creamy beige with dark speckles above but spotless below.

Colour and pattern in life ( Fig. 4 ). As for preserved specimens but colours richer and more lustrous. The dorsal beige is slightly darker on the head and body, gradually lightening towards the tail.

Comparison with congeners ( Fig. 5 ). Thirty-eight Lerista have no trace of forelimbs, two of which are completely limbless ( L. ameles Greer, 1979 and L. apoda Storr, 1976 ). Lerista munuwajarlu sp. nov. has didactyl hindlimbs; however, given the limited sample size and known toe-number variation within some Lerista species ( Amey & Worthington Wilmer 2014; Amey & Edwards 2017; Amey et al. 2018), this trait has been excluded from further comparisons. Of the remaining 36 congeners, 15 have a free interparietal and frontoparietals (i.e., not fused into a single scale): L. alia Amey, Couper & Worthington Wilmer, 2019a , L. allanae Longmann, 1937 , L. anyara Amey, Couper & Worthington Wilmer, 2019b , L. carpentariae , L. cinerea Greer, McDonald & Lawrie, 1983 , L. hobsoni Amey, Couper & Worthington Wilmer, 2016 (in Couper et al. 2016), L. karichigara Zozaya, Vanderduys, Macor, Read & Amey, 2025a , L. karlschmidti , L. parameles Amey, Couper & Worthington Wilmer, 2019a , L. rochfordensis Amey & Couper, 2009 , L. storri Greer, McDonald & Lawrie, 1983 , L. stylis , L. vanderduysi , L. vittata Greer, McDonald & Lawrie, 1983 , and L. wilkinsi . Of these, L. allanae , L. anyara , L. cinerea , L. hobsoni , and L. rochfordensis have a prefrontal but none of these five species have a broad, bold, dark upper-lateral stripe.

Distribution and habitat ( Fig. 6 ). Currently known from a single site on Pungalina-Seven Emu Sanctuary in the Gulf Coastal Bioregion, NT ( Fig. 1 ). The habitat is tall open savanna woodland dominated by Darwin Stringybark ( Eucalyptus tetrodonta ) on deep sandy soil of Cainozoic sand deposits. Cypress Pine ( Callitris intratropica ) is present in places, and typical shrubs include Acacia torulosa , Grevillea pteridifolia , Jacksonia odontoclada , Dodonaea hispidula , Boronia lanuginosa and Bossiaea bossiaeoides . Common ground cover species are Triodia sp. , Chrysopogon fallax, Aristida holathera, Eriachne mucronata and Scaevola revoluta . More broadly, the Gulf Regional Land System is summarised as Horse Creek (Alh); “Gently undulating plains of sandstone with deep sandy soils and isolated swampy depressions. Siliceous sands and earthy sands. Tall open woodland of E. tetrodonta , Callitris intratropica , E. miniata and E. ferruginea . Eucalyptus polycarpa and Melaleuca viridiflora occur on wetter areas.” ( Aldrick & Wilson 1990).

Suggested IUCN Red List status. Assessing the conservation status of L. munuwajarlu sp. nov. is challenging. Because the species is known from only two specimens collected at a single location, the extent of occurrence (EOO) cannot be calculated, while the area of occupancy (AOO) is estimated at only 4 km ² under IUCN Red List guidelines ( IUCN 2024), fulfilling the quantitative threshold for listing as Critically Endangered (CR) under Criterion B of the IUCN Red List. More survey work is needed to better estimate the true distribution of this species. Nevertheless, to qualify under Criterion B there must also be evidence of either: observed, estimated, inferred, or projected declines in any of (i) EOO, (ii) AOO, (iii) area, extent or quality of habitat, (iv) number of locations or subpopulations, or (v) number of mature individuals; or else extreme fluctuations in any of these categories. While Pungalina-Seven Emu is actively managed for conservation by the Australian Wildlife Conservancy (AWC), it remains susceptible to threats such as altered fire regimes, incursion of weeds and pest species, and climate change. Despite a recent declaration under The Petroleum Act that protects Pungalina-Seven Emu holdings from mining, much of the broader region has no such protection and is subject to additional pressures, including cattle production with associated introduced pasture plants ( Cowley et al. 2015; Clements & Henzell 2010), and uncontrolled broadscale late-season fires ( Russell-Smith et al. 2003). Category 4 Severe Tropical Cyclone Trevor hit Pungalina-Seven Emu in 2020, followed by an intensely hot fire in late 2021 ( BOM 2025; Palma et al. 2022), and then another two tropical cyclones—Lincoln and Megan—in 2024 ( BOM 2025). These events dramatically changed the appearance of the habitat where L. munuwajarlu sp. nov. has been recorded. The Darwin Stringybark canopy is now much more open and lower in stature, and live mature Cypress Pine are now rare (J. Kemp, pers. obs.). Lerista typically favour loose soil and/or mats of leaf-litter. Ground debris and leaf-litter piles are important refuges and microhabitats for the genus. Though not rigorously assessed, structural changes to shrub and ground cover, especially reduced leaf-litter cover due to a depleted canopy, seem a likely consequence of the recent extreme fire and weather events (J. Kemp, pers. comm.). The true impact of such events, however, and the risk posed to L. munuwajarlu sp. nov. by other potential threats cannot be determined without more data and long-term monitoring. While quantitative thresholds for CR are met under Criterion B, this substantial uncertainty regarding population impacts precludes such a classification. Considering the documented habitat degradation at its single known site, we recommend listing it as Near Threatened (NT) pending additional data on the impacts of potential and inferred threats.

Figures

FIGURE 1. Occurrence records for Lerista munuwajarlu sp. nov. (orange star) and the five other Lerista species in the northeastern Northern Territory. Localities and geographic features mentioned in the main text are labelled. Records that are not based on material examined (Table 1) represent museum vouchers or fauna survey records obtained from the ALA (2025). Some points are slightly offset for visual clarity.

FIGURE 3. Head scalation in lateral profile for (top) Lerista munuwajarlu sp. nov. holotype MAGNT R39264 and (bottom) L. carpentariae MAGNT R39087 (Limmen National Park), highlighting consistent differences between the species with respect to supraoculars (turquoise), supraciliaries (orange), loreals (purple), and the presence of a prefrontal in L. munuwajarlu sp. nov. Other differences apparent here were inconsistent across specimens. Note that the first nuchal is fused to the secondary temporal in the holotype (illustrated here) but is separated in the paratype MAGNT R37167, as shown by the dashed grey line. Illustrations are not to scale.

FIGURE 4. Lerista munuwajarlu sp. nov. in life: (A) holotype MAGNT R39264; (B) paratype MAGNT R37167. Photos: A. Zimny (A); E. Vanderduys (B).

FIGURE 5. Four Lerista species that occur within or immediately adjacent to the Gulf Coastal Bioregion: (A) L. munuwajarlu sp. nov. holotype MAGNT R39264; (B) L. carpentariae MAGNT R39087 from Limmen NP; (C) L. griffini from the Sturt Plateau (unvouchered); and (D) L. orientalis from Pungalina-Seven Emu (unvouchered). Photos: S. Zozaya (A,B) and A. Zimny (C,D).

FIGURE 6. Habitat of Lerista munuwajarlu sp. nov. at the type locality. Capture sites of the holotype (A) and paratype (B), and photos of adjacent woodland (C,D). Photos: A. Zimny (A,B); S. Zozaya (C,D).