Oedura argentea, Hoskin & Zozaya & Vanderduys, 2018
Hoskin, Conrad J., Zozaya, Stephen M. & Vanderduys, Eric, 2018, A new species of velvet gecko (Diplodactylidae: Oedura) from sandstone habitats of inland north Queensland, Australia, Zootaxa 4486 (2), pp. 101-114: 104-109
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Oedura argentea sp. nov.
Silver-eyed velvet gecko
Paratypes. Cobbold Gorge, Robin Hood Station (18°48'58" S, 143°24'25" E): QM J96297 View Materials , female; QM J96301 View Materials , juvenile female; QM J96302 View Materials , male; QM J88140 View Materials , male; QM J88141 View Materials , female. Littleton National Park (18°13'33" S, 142°44'52" E): QM J88195 View Materials , female. 23.9 km E Croydon via Gulf Hwy (approximate coordinates 18°13' S, 142°26' E): AMS R63690 View Materials , male; AMS R63691 View Materials , female. Donkey Springs, Bulleringa National Park (17°35'13" S, 143°48'47" E): QM J74565 View Materials , female.
Additional material. An additional 32 individuals were examined and/or photographed in life to assess colour pattern: twenty from Cobbold Gorge (18°49' S, 143°24' E), three from Littleton National Park (18°13' S, 142°43' E), and nine from Gilberton Station (18°12' S, 143°49' E). Prior to release, 14 of these additional individuals were measured for SVL, of which seven were adult males examined to count the number of pre-cloacal pores.
Diagnosis. Oedura argentea sp. nov. is a relatively small (SVL 61–80 mm) species of Oedura with a relatively wide (HW/SVL = 0.19–0.20) and flat (HD/SVL = 0.10–0.13) head; rostral scale only partially divided by medial vertical groove; iris silvery with reticulated golden-brown venation; tail moderately short (original TL/SVL = 0.64–0.77; regenerated TL/SVL = 0.51–0.66), narrow (original TW/TL = 0.13–0.18; regenerated TW/TL = 0.18– 0.24) and circular in cross-section; adult colouration consisting of 5–6 (usually 5) dark-edged, relatively straight, pale bands from the neck to pelvis, separated by mottled purplish-grey and yellow interspaces; backswept pale nuchal band continuous with pale line along the mouth to the snout; single cloacal spur on each side; 14–22 precloacal pores in adult males.
Etymology. From the Latin adjective argenteus, meaning silver or silvery, in reference to the silvery iris of this species, which is unique among eastern Australian Oedura . The name is used here as an adjective in its feminine form.
Measurements and scalation of holotype ( Figs. 1–2 View FIGURE 1 View FIGURE 2 ). QM J96296 View Materials (male) SVL = 67.4 mm; T = 46.1 mm (original); TW = 6.1 mm; TD = 5 mm; HL = 16.7 mm; HW = 12.7 mm; HD = 6.7 mm; S = 6.6 mm; EN = 6; EE = 6.74 mm; IN = 2.2 mm; IO = 5.9 mm; EYE = 3.3 mm; NL = 15.3 mm; AG = 28.8 mm; FL = 8.8 mm; HLL = 9.9 mm; 19 interorbital scales; 2 scales contacting dorsal edge of rostral; rostral crease 50% of rostral depth; 6 scales bordering nostril; 12 supralabials; 11 infralabials; 1 scale bordering posterior edge of mental; cloacal spurs 1/1; 17 pre-cloacal pores (8 left, 9 right) separated medially by a single granular scale; lamellae = 8 for all toes; lamellae 3rd finger = 8.
Description of type series ( Fig. 2 View FIGURE 2 ). Data presented as range followed by mean in brackets. Measurements (mm). SVL = 61.8–80.1 (70.0); T(original) = 41.9–49.3 (45.6); T(regenerated) = 35.5–52.5 (45.2); TW = 6.1–8.8 (8.0); TD = 4.9–6.8 (5.9); HL = 15.8–18.7 (17.4); HW = 12.2–14.3 (13.5); HD = 6.3–9.6 (7.9); S = 5.9–8.4 (7.3); EN = 6.1–7.1 (6.5); EE = 6.1–8.2 (7.0); IN = 2.2–2.9 (2.6); IO = 5.4–6.9 (6.1); EYE = 3.2–4.0 (3.6); NL = 10.7– 18.5 (15.8); AG = 26.8–34.3 (31.2); FL = 7.5–9.2 (8.7); HLL = 9.6–11.0 (10.3). Head. Distinct from neck, relatively narrow (HW/SVL = 0.19–0.20), moderately depressed (HD/SVL = 0.10–0.13), and covered in small granular scales that are largest on the dorsal and lateral surfaces of the snout; interorbital counts 17–21 (18.8); rostral scale approximately twice as wide as deep, divided 30–50% (mean 36%) vertically by a medial groove; rostral contacting nostril, bordered by 2 scales along its dorsal edge, and bordered laterally on each side by the first supralabial scales; 6 scales contacting nostril; supralabials 11–13 (11.4); first supralabial narrower than second supralabial; infralabials 9–12 (10.3); enlarged granular scales extending back from mental scale, decreasing in size towards small ventral scales; ear opening small and diagonally or horizontally elongate. Body. Moderately robust (AG/SVL 0.42–0.47), slightly depressed, covered in small granular scales; scales on ventral surface about the same size as those on dorsum; scales on lateral and dorsolateral surfaces arranged in transverse rows; 1 enlarged cloacal spur behind the lower posterior margin of the thigh in both sexes, typically more well-defined in males; row of 14– 20 (17) pre-cloacal pores in mature males divided medially by 1–2 granular scales, extending to underside of thigh; pre-cloacal pores not evident in females. Limbs. Moderately long (FL/SVL = 0.12–0.14; HLL /SVL = 0.14–0.15); digits dorsoventrally compressed and expanded distally, each with an enlarged pair of apical lamellae followed by a transverse series of lamellae that are divided distally and single proximally; apical pair of lamellae discontinuous with other lamellae; hindlimb with 5–8 (6.3) enlarged lamellae (including apical pair) on 1 st toe , 6–8 (6.9) on 2nd toe, 8 on 3rd toe, 7–9 (8.0) on 4th toe and 6–9 (7.2) on 5th toe; forelimb with 6–8 (7.6) enlarged lamellae (including apical pair) on 3rd finger. Original tail. Moderately short (original TL/SVL = 0.64–0.77; regenerated TL/SVL = 0.51–0.66), relatively narrow (original TW/TL = 0.13–0.18; regenerated TW/TL = 0.18–0.24), and tapered; scales arranged in concentric rings, about the same size on the dorsal and on ventral surfaces. Colouration in spirit. Dorsal pattern consists of 5 (N = 9; Gregory Range specimens) or 6 (N = 1; QM J74565 View Materials , Bulleringa National Park) distinct transverse pale cream bands from the neck to pelvis (i.e., dorsally between the hindlimbs), with a background colour of mottled brownish-grey and cream-brown between the bands. The external margins to each pale cream band is darker brownish-grey, with the cream-brown mottling often arranged transversely, resulting in indistinct cream-brown bands within the brownish-grey interspaces. The pale cream bands are mottled within by indistinct brownish-grey mottling that also tends to form obscure transverse medial bands. Bands along the dorsum are generally straight-edged and do not become significantly narrower on the flanks. Patterning terminates on the lower flanks, giving way to a pale cream ventral surface with dark stippling on the lateral edges. In the juvenile specimen (QM J96301 View Materials ) the pale bands and dark interspaces are less mottled and more starkly defined. Distinct, pale nuchal band sweeps forward unbroken to the snout enclosing ear and running along jaw and labials; bordered on top by a dark band from snout, through eye, and around the back of the head. Top of head cream-brown, mottled with brownish-grey. The area above each eye is blue-grey. Infralabials with dark stippling forming blotches or bars along length of lower jaw and chin, becoming less distinct on the throat. Limbs mottled brownish-grey and creambrown, similar to dorsal background colour. Ventral surfaces of limbs lighter cream with dark stippling. Tail consists of an alternating series of pale and dark bands of varying definition, typically forming 5–6 broad pale bands with dark blotching, each followed by dark bands with pale blotching or narrow bars. Banding disappears on ventral surfaces of tail, replaced by cream background colour with brownish-grey mottling and flecks. Cloacal spur white.
Colouration in life ( Figs. 1 View FIGURE 1 , 3–5 View FIGURE 3 View FIGURE 4 View FIGURE 5 ). Dorsal pattern consists of five well-defined, broad, grey-white bands from the back of the neck to the pelvis, on a background colour of mottled purplish-grey and yellow. The pale bands often have grey mottling within them (particularly medially) and are often thinly bordered within by yellow scales. The proportion of purplish-grey and yellow in the background colour varies considerably, with some individuals possessing relatively little yellow ( Fig. 3C View FIGURE 3 ) and others dominated almost entirely by yellow ( Fig. 3D View FIGURE 3 ). The purplish-grey background colour is always more pronounced along the edges of the pale bands, particularly dorsally. Tail consists of an alternating series of white, purplish-grey, and yellow bands of varying definition, typically forming 5–6 broad whitish bands enclosing dark blotching or bars, each followed by a darker band with varying degrees of yellow and purplish-grey mottling. The pale bands on the tail are typically lighter than those on the back. Patterning is otherwise similar to specimens in spirit. The iris is silver with reticulated golden-brown venations that can give the eye a gold-and-silver appearance when viewed from further away ( Fig. 3B View FIGURE 3 ).
SVL and pre-cloacal pore counts in life. SVL 62–74 (68.7) mm; pre-cloacal pores 17–22, separated medially by 1–3 granular scales.
Comparison with other species ( Figs. 4–5 View FIGURE 4 View FIGURE 5 ). Oedura argentea sp. nov. differs from O. castelnaui , with which it is widely sympatric, by its smaller size (SVL 63–80 mm versus 81–95 mm), relatively wider head (HW/SVL = 0.19–0.20 versus 0.16–0.18), narrower tail (often relatively wide and carrot-shaped in O. castelnaui ), and in possessing relatively straight transverse pale bands that do not become significantly narrower on the flanks (versus backwards sweeping, V-shaped pale bands that often narrow toward the flanks; Fig. 4 View FIGURE 4 ).
It is easily distinguished from O. coggeri ( Fig. 5E View FIGURE 5 ), O. jowalbinna , O. monilis ( Fig. 5F View FIGURE 5 ), and O. tryoni by its pattern consisting of 5–6 dark-edged, transverse pale bands from the neck to pelvis (versus pale ocelli and occasionally transverse bands or blotches in O. coggeri , O. monilis , and O. tryoni , or neck and pelvis band but patternless back in O. jowalbinna ).
Colour pattern is most similar to members of the O. marmorata group. Differs from O. bella ( Fig. 5C View FIGURE 5 ), O. marmorata , and O. gemmata in possessing only a single cloacal spur (versus 2–3), and further differs from O. marmorata and O. gemmata by its narrow tail that is circular in cross-section and never wider than the head (versus flattened and approaching or exceeding head width). Differs from O. cincta ( Fig. 5D View FIGURE 5 ) and O. fimbria in possessing only a single post-cloacal tubercle (versus up to 4), by its smaller adult size (SVL 61–80 mm versus 78–108 mm in O. cincta and 71–104 mm in O. fimbria ), and further differs from O. cincta by its partially divided rostral scale (versus usually fully divided). It also differs from these two species in retaining a well-defined dark-edged banded pattern throughout adulthood (versus usually but not always becoming indistinct in large adults).
Differs from O. luritja by its smaller adult size (SVL 61–80 mm versus 85–99 mm), its deeper head (HD/SVL = 0.10–0.13 versus 0.07–0.09), possessing a backswept pale nuchal band (bordered on top by a distinct dark postorbital band) that is continuous from the mouth over the back of the head and neck (versus pale nuchal band not continuous with the pale line along mouth), and in possessing a higher number of pre-cloacal pores in adult males (14–22 versus 10–16). Additionally, in life, the pale bands of O. luritja are yellowish ( Fig. 5B View FIGURE 5 ), whereas in O. argentea sp. nov. the pale bands are whitish-grey.
Differs from O. gracilis by its much shorter tail (versus very long and narrow, approaching length of the body), its whitish-grey bands (versus yellowish), and by its flared proximal lamellae on toes 2–5 that approach the width of the apical plates (versus narrow and tapering).
Differs from O. filicipoda and O. murrumanu by its much smaller adult size (SVL 61–80 mm versus 85–105 mm) and in possessing a distinct backswept whitish nuchal band (bordered on top by a dark post-orbital band) that is continuous from the mouth through the ear and over the back of the head (sometimes present in O. murrumanu but cream coloured, and post-orbital band weakly defined). Further distinguished from O. filicipoda by its narrow tail that is circular in cross-section and not wider than the head (versus wider and flattened).
Distribution. Currently known only from sandstone outcropping of the Gregory Range and the Bulleringa area in central-north Queensland, Australia ( Fig. 6 View FIGURE 6 ). The species has been recorded from four sites: Gilberton Station, Cobbold Gorge, Littleton National Park, and Donkey Springs in Bulleringa National Park ( Fig. 6 View FIGURE 6 ). Further searches will likely find this species elsewhere in the sandstone formations of the region. The Gilberton and Cobbold Gorge sites fall within the Hampstead Sandstone Formation and the Littleton and Bulleringa sites falls within the Gilbert Sandstone Formation.
Ecology. Oedura argentea sp. nov. is restricted to sandstone outcrops and escarpments ( Fig. 7 View FIGURE 7 ). Individuals are typically found at night foraging on sandstone cliff faces and pavements but have also been found at night on nearby vegetation, particularly small, thin trees. We have observed them emerging from narrow rock crevices at dusk.
Localities were mapped into Queensland’s Regional Ecosystem mapping framework (Queensland Herbarium, 2016) to identify the underlying Regional Ecosystem (RE). The Cobbold Gorge individuals were all found on sandstone in a vegetation community mapped as RE 9.10.1c. The Littleton National Park individuals were located on sandstone within RE 9.11.30 a. The Gilberton Station individuals were located on sandstone within areas mapped as RE 9.12.11. The Bulleringa National Park specimen was collected from sandstone within an area mapped as RE 2.10.2 and RE 2.10.5. As a coarse summary, all these REs are open Eucalyptus and Acacia woodland, with a ground layer of exposed rock, bare ground, and spinifex ( Triodia ).
Genetics. ND4 mtDNA sequence data indicates O. argentea sp. nov. is sister to the clade containing O. castelnaui (mean pairwise divergence 17%) and O. coggeri (mean pairwise divergence 15%). The two O. argentea sp. nov. sequences from Cobbold Gorge are very similar (<1.5%) and about 4% divergent to the sequence from Littleton National Park. Thus, mtDNA sequence data support O. argentea sp. nov. as a distinct species within the ‘ tryoni group’. Genbank accession numbers for these sequences are: MH899070 View Materials – MH899072 View Materials .
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