Oedura atra, Hoskin, 2025

Hoskin, Conrad J., 2025, A new species of velvet gecko (Diplodactylidae: Oedura) from basalt habitat of inland north Queensland, Australia, Zootaxa 5583 (3), pp. 549-559 : 552-558

Oedura atra sp. nov.

Basalt Velvet Gecko

( Figs. 3–5A )

Material examined. Holotype. QM J98083 , female, Sturgeon Basalt,north of Hughenden ,(-20.67680°, 144.16797°), collected by C. J. Hoskin, 1 October 2022, field collection code conx6580.

Paratypes. QM J98082 (female), J98084 (male), J98085 (male), collection details as for holotype, field collection codes conx6579, conx6581, conx6582, respectively .

Diagnosis. Oedura atra sp. nov. is a medium-sized Oedura with a body pattern of narrow, pale bands on a dark background; a tail that is relatively short (original TL/SVL 0.55–0.58; regrown TL/SVL 0.46–0.47) and wide (original TW/TL 0.24–0.30; regrown TW/TL 0.34–0.35); a relatively wide head (HW/SVL 0.20–0.21); a pale nuchal band that is narrowly continuous with the pale line along the mouth to the snout; a single cloacal spur on each side; a dark brown/copper iris; and a rostral scale only partially divided by a medial vertical groove.

Etymology. From the Latin adjective atra , meaning black or dark, in reference to the dark colouration of this species. The name is used here as an adjective.

Measurements and scale counts of type series. Table 1 .

Description of type series. Medium-sized (SVL 76.90–84.30 mm, mean 80.94 mm). Head. Distinct from neck and relatively broad (HW/SVL = 0.20–0.21), moderately depressed (HD/SVL = 0.10–0.11), and covered in small granular scales that are largest on the dorsal and lateral surfaces of the snout; interorbital counts 18–20; rostral scale approximately twice as wide as deep, divided 40–50% vertically by a medial groove; rostral contacting nostril, bordered by 2–3 (mean 2.25) scales along its dorsal edge, and bordered laterally on each side by the first supralabial scales; 6 scales contacting nostril; supralabials 10–12 (10.75); second supralabial wider and taller than first; infralabials 9–10 (9.5); mental scale contacts first infralabials and a single granular throat scale that is three or four times larger than the subsequent granular throat scales; other scales contacting infralabials about twice the size of granular throat scales and grading quickly into these in one or two rows; granular scales on throat minute and even-sized; ear opening small, and rounded to vertically elongate. Body. Moderately robust (AG/SVL 0.45–0.49), slightly depressed, covered in small granular scales; scales on ventral surface slightly larger than those on dorsum; scales on lateral and dorsolateral surfaces arranged in transverse rows; 1 low, blunt, post-cloacal tubercle behind the lower posterior margin of the thigh in both sexes, typically more well-defined and broader in males; pre-cloacal pore counts on the two males 14 and 11, divided medially by 3 and 4 granular scales without pores, respectively; pre-cloacal pores not evident in females. Limbs. Moderately long (FL/SVL = 0.13–0.15; LHL/SVL = 0.14–0.16); pentadactyl; digits dorsoventrally compressed and expanded distally, each with an enlarged pair of apical lamellae followed by a transverse series of lamellae that are single proximally and divided distally; apical pair of lamellae discontinuous with other lamellae; hindlimb with 6–7 (6.25) enlarged lamellae (including apical pair) on 1 st toe, 7–8 (7.5) on 2 nd toe, 8 on 3 rd toe, 8–9 (8.25) on 4 th toe (with proximal 3 or 4 lamellae single and distal 5 lamellae split/paired), and 8 on 5 th toe; forelimb with 7 enlarged lamellae (including apical pair) on 3 rd finger (with proximal 3 lamellae single and distal 4 lamellae split/paired). Original tail. Moderately short (original TL/SVL = 0.55–0.58) and broad (original TW/TL = 0.24–0.30), and slightly depressed (original TD/TL = 0.16–0.19); rectangular scales arranged in a block-like pattern of concentric rings; scales similar size on dorsal and ventral surfaces, and about twice the size of those on body. Regrown tail. Short (regrown TL/SVL = 0.46–0.47), bulbous (regrown TW/TL = 0.34–0.35), and moderately depressed (regrown TD/TL = 0.23–0.25); scales as for original tail. Colouration in spirit ( Fig. 3 ). Dorsal pattern consists of five, transverse, white bands from nape band to band over hips. These white bands are generally unbroken, except QM J98084 which has a narrow, medial break in bands one to four, and QM J98083 which has a break in band four. White bands about one-quarter or less of the width of the dark space in between. Bands essentially straight (transverse), with a slight U-shape to some (including the nape band in all specimens). White bands extend down the lateral surfaces and terminate at the edge of the ventral surface, where narrow black edging encloses each band. Each white band is bordered on its anterior and posterior edge by a diffuse black marking (‘band’) of similar width, which has a sharp edge with the white band but merges into the dark spaces in between. Background colour between bands is heavy dark brown mottling on a light brown background. White bands continue onto original tail (QM J98082 and QM J98084 ) as five white bands of similar width to body bands, but tail banding less distinct because the dark areas in between the bands are also marked with white, transverse dashes and spots. Regrown tails (QM J98083 and QM J98085 ) black with transverse white or cream dashing. White nuchal band more of less connects over ear opening to white band along supralabials, but narrow and often broken behind ear opening/edge of nape and corner of gape. Sides and top of head otherwise uniformly dark grey/brownish with diffuse darker marking around the edge. Darker along canthal area to snout. Forelimbs dark greyish brown with diffuse dark brown mottling. Hindlimbs dark greyish brown with diffuse paler mottling to give the appearance of indistinct paler spots (e.g., QM J98082 ). Ventral surfaces of throat, neck, body and limbs evenly cream-coloured, with a grey tinge on underside of limbs. Underside of original tails white down the center, with pattern from lateral tail surfaces extending under on the edges. Underside of regrown tails dark grey, similar to dorsal and lateral surfaces but paler and without white dashes. Cloacal spurs white.

Colouration in life ( Figs 4 , 5A ). As described above, but colour pattern more pronounced—pale body bands whiter, dark areas in between darker (and with a purplish tinge), background colour more yellowish, and bands and other pale markings on tail more yellowish. Some adults are very dark (e.g., Fig. 5A ), while other adults have darker markings more limited to the edges of the pale bands and tail, with more pale/yellow background colouration (e.g., Fig. 4B ). Subadults (e.g., Fig. 4E ) and juveniles (e.g., Fig. 4F ) have a simple pattern of thin, white or cream bands on the body and tail, on an evenly dark grey or black background. Iris dark brown coloured with fine copper or silver markings throughout.

Additional morphological data. SVL of six adults measured in the field was 72–90 mm (av. 80.5 mm), consisting of five males measuring 72–81 mm (av. 79 mm) and a female measuring 90 mm. A sub-adult ( Fig. 5E ) was 59 mm, and a juvenile ( Fig. 5F ) was 39 mm. The number of pre-cloacal pores on two adult males was 15 and 16, and the pore gap was 3 and 4 scales, respectively.

Genetic data. ND4 mtDNA sequences for two individuals in the type series (QM J98083 = PP555299, QM J98084 = PP555300) are uploaded to GenBank. A phylogeny including congeners that are morphologically most similar, and samples from close to the distribution of O. atra sp. nov., places O. atra sp. nov. as a divergent lineage allied to O. argentea in the broader ‘ O. coggeri ’ species group ( Fig. 2 ). Uncorrected ND4 sequence divergence between O. atra sp. nov. and O. argentea averages 11.6%, and divergence between O. atra sp. nov. and O. coggeri , O. castelnaui and O. monilis averages 12.7%, 15.8% and 18.5%, respectively. The ND4 phylogeny provides a preliminary assessment of relationships, and more thorough genetic analysis involving more genes, more species, and more localities within species is required to better test the phylogenetic placement of O. atra sp. nov.

Comparison with other species. Oedura atra sp. nov. is readily distinguished from all other Oedura species by the combination of having a single post-cloacal tubercle on each side and body pattern of slender, pale, transverse bands on a dark background, with the transverse bands being much narrower than the width of the darker area between them ( Figs 4A , 5 ). Oedura atra sp. nov. is most similar to the other Oedura species in inland northeastern Queensland with patterns consisting of transverse bands or bars— O. argentea , O. castelnaui and O. monilis ( Fig. 5 ). It is not known to co-occur with any of these species ( Fig. 1 ), but further surveys may find species in close proximity. Oedura atra sp. nov. is distinguished from O. argentea ( Fig. 5B ) by narrow bands on body (versus broad), dark iris (versus silver), original and regrown tails relatively short (original TL/SVL 0.55–0.58 versus 0.64–0.77; regrown TL/SVL 0.46–0.47 versus 0.51–0.66) and wide (original TW/TL 0.24–0.30 versus 0.13–0.18; regrown TW/TL 0.34–0.35 versus 0.18–0.24), and lower number of pre-cloacal pores in adult males (11–16 versus 14–20). Oedura atra sp. nov. is readily distinguished from O. castelnaui ( Fig. 5D ) by narrow, straight bands on body (versus broad, backward-sweeping bands), and wider head (HW/SVL 0.20–0.21 versus 0.16–0.19). Oedura atra sp. nov. is readily distinguished from O. monilis ( Fig. 5C ) by body pattern of narrow bands (versus blotches and/or transverse bars, and at least some pale lateral spots), and by connection (albeit narrow) of nuchal band to white band along mouth (versus no connection between nape bar/blotches and pale band along mouth in O. monilis ). Oedura coggeri also occurs in the same general region as O. atra sp. nov. (although they are very unlikely to co-occur) and O. atra sp. nov. is readily distinguished from that species by bands on body (versus spots, blotches or broken bars in O. coggeri ), no spotting on the legs (versus limbs spotted), and larger size (max. SVL 90 mm versus 81 mm). Oedura atra sp. nov. differs from O. cincta De Vis, 1888 (which occurs to the south-west of the area shown in Figure 1 ) by body pattern of narrow pale bands (versus typically, broad bands), having only a single post-cloacal tubercle on each side (versus up to 4), and by its partially divided rostral scale (versus usually fully divided).

Distribution. Currently known from two areas of basalt rock scree slopes north of Hughenden ( Figs 1 , 6 ). The two areas are 23 km straight-line apart. The scree slopes are part of the extensive Sturgeon Basalt outcropping that extends from north of Hughenden approximately 100 km west to near Richmond ( Fig. 1 ). Further surveys are likely to find O. atra sp. nov. at other sites in this extensive basalt outcropping.

Habitat and natural history notes. Oedura atra sp. nov. is known from exposed, piled, black basalt rocks. At the two known sites, the basalt outcropping is about 150 m wide, forming the slopes of an extensive linear plateau/outcropping. The habitat is primarily bare rocks (e.g., Fig. 6 ), with some vegetation growing among the rocks. Oedura atra sp. nov. has only been found on basalt rocks, or on the trunks of small trees growing among the rocks, in areas of deeply piled rock. It is active at night and retreats into deep crevices and holes in the rocks when disturbed. Surveys in woodland around the known sites have not found this species. There is little information on breeding biology. Surveys in both October and February found females with two well-developed eggs visible through the body wall, and both surveys found juveniles (<40 mm SVL; e.g., Fig. 4F ). Data so far suggests females may be larger than males, with the SVL of three adult females (83 mm, 84 mm, 90 mm) being greater than all seven adult males measured (av. 78.5 mm, 72–81 mm). 7 of 12 adults assessed (58%) had original tails. Other gecko species co-occurring on the basalt rocks were Gehyra dubia ( Macleay, 1877) , Heteronotia binoei ( Gray, 1845) , and Nephrurus asper Günther, 1876 .

Conservation. Oedura atra sp. nov. is only known from a small area but it is highly likely to have a larger distribution. The Sturgeon Basalt outcropping is narrow, ranging from about 50 m to 400 m wide (and averaging about 100 m wide) along its length, but it has a convoluted linear extent of at least 800 km. Surveys to date have found the species in areas of more deeply layered basalt rocks and not in areas where the rock is primarily just a surface layer. This suggests the distribution will be patchy, and may comprise many isolated or sem-isolated populations. Further surveys are required to determine how widespread O. atra sp. nov. is along the Sturgeon Basalt outcropping, and to assess potential threats. Until then, the species should be considered Data Deficient under IUCN Red List criteria.

Figures

FIGURE 1. Map of inland north-east Queensland showing the known locality for O. atra sp. nov. (pink stars) and records of the four other Oedura species in the region. Note the fine black ‘squiggle’ lines of the Sturgeon basalt outcropping north and west of Hughenden (within the dashed ellipse). The east to west extent of this outcropping is about 100 km. Inset map shows Australia.

FIGURE 2. Maximum-likelihood phylogeny of Oedura species of inland north-east Queensland, based on approximately 850 bp ND4 mtDNA, with O. monilis used as the outgroup. The O. atra sp. nov. sequences are marked in pink. All sequences for other species come from as close to the distribution of O. atra sp. nov. as possible. GenBank accession code and locality are presented for all sequences. All localities are marked on Figure 1. The scale bar shows 4% uncorrected sequence divergence.

FIGURE 3. Dorsal view of the holotype (far left) and the three paratypes of O. atra sp. nov. Specimens from left to right: QM J98083, QM J98084, QM J98082, QM J98085.

FIGURE 4. Oedura atra sp. nov. in life: (A, B) adults with original tails, (C) ventral surface of adult with an original tail (note egg visible through ventral surface), (D) adult with regrown tail, (E) subadult with original tail (note skin about to shed), (F) juvenile with original tail. Panel D shows QM J98082 in life; the other individuals were photographed in the wild and not collected.

FIGURE 5. Comparison of O. atra sp. nov. (A) with nearby Oedura species with body pattern of bands or elongate blotches: O. argentea (B), O. monilis (C), O. castelnaui (D). Photos: Scott Macor (A), Stephen Zozaya (C), Conrad Hoskin (B, D).

FIGURE 6. Habitat of O. atra sp. nov. north of Hughenden. Oedura atra sp. nov. appears to be restricted to the piled basalt rocks and has not been found in the surrounding woodland.