Oligosoma burganae, Chapple, David G., Bell, Trent P., Chapple, Stephanie N. J., Miller, Kimberly A., Daugherty, Charles H. & Patterson, Geoff B., 2011

Chapple, David G., Bell, Trent P., Chapple, Stephanie N. J., Miller, Kimberly A., Daugherty, Charles H. & Patterson, Geoff B., 2011, Phylogeography and taxonomic revision of the New Zealand cryptic skink (Oligosoma inconspicuum; Reptilia: Scincidae) species complex, Zootaxa 2782, pp. 1-33 : 19-22

publication ID	https://doi.org/ 10.5281/zenodo.205462
DOI	https://doi.org/10.5281/zenodo.6182744
persistent identifier	https://treatment.plazi.org/id/03AC4C11-8D30-A420-FF4C-FB2AFCEF4AF7
treatment provided by	Plazi
scientific name	Oligosoma burganae
status	sp. nov.

Treatment

Oligosoma burganae sp. nov.

Figure 7 View FIGURE 7. a

Leiolopisma inconspicuum Patterson & Daugherty 1990: 66 Leiolopisma nigriplantare maccanni Patterson 1984

Holotype. Burgan Stream, Rock and Pillar Range (45º 35’S, 169º 56’E), RE002390/1, adult female (coll. G. Patterson, 1982).

Paratypes (13 specimens). Burgan Stream, Rock and Pillar Range (45º 35’S, 169º 56’E), 12 specimens (RE006149 [CD765], male; RE006150 [CD766], female; RE006151 [CD767], male; RE006152 [CD768], female; RE006153 [CD769], female; RE006154 [CD770], male; RE006155 [CD771], male; RE006156 [CD772], female; RE006157 [CD773], female; RE006159 [CD774], female; RE006160 [CD775], male; RE006161 [CD776], female) (coll. G. Patterson, April 1984); Burgan Stream, Rock and Pillar Range (45º 35’S, 169º 56’E), RE002391/ 1, female (coll. G. Patterson, November 1981).

Diagnosis. Oligosoma burganae can be distinguished from other related Oligosoma species through a combination of characters ( Figure 4 View FIGURE 4 a – b ). Compared to O. maccanni , O. burganae has a glossy appearance, with brown predominating whereas O. maccanni has a greyer ground colour. Oligosoma maccanni has a pale grey ventral colour rather than the yellow/grey ventral colour seen in O. burganae . The ear opening in O. maccanni often has large projecting scales on the interior margin, whereas these are often minimal or lacking altogether in O. burganae . Longitudinal striping is more pronounced in sympatric populations of O. polychroma , which almost always have a pale dorsal stripe on the outside of the forelimbs. The ear opening in O. polychroma often has prominent projecting scales on the interior margin. There are statistical differences between O. burganae and O. inconspicuum (AG/SF, HL/HW, SE/EF, SVL/HL, SVL/FLL), O. toka sp. nov. (SVL/HLL, ventral scales), O. notosaurus (ventral scales), and O. repens sp. nov. (SVL/HL, SVL/FL, AG/SF) ( Figure 4 View FIGURE 4 a – b ). All O. inconspicuum have four supraoculars whereas most O. burganae have only three supraoculars. Oligosoma repens sp. nov. has a more elongate appearance than O. burganae (TL/SVL of 1.1 and 1.28, respectively). The number of subdigital lamellae (18–23) is greater than in O. tekakahu (16). The head of O. burganae is noticeably blunter and deeper than O. repens sp. nov. and O. toka sp. nov. ( Figures 4 View FIGURE 4 a – b , 7–9 View FIGURE 7. a View FIGURE 8. a View FIGURE 9. a ).

Description of holotype. Body elongate, oval in cross-section; limbs moderately well-developed, pentadactyl. Lower eyelid with a transparent palpebral disc, bordered on sides and below by small, oblong granules. Nostril centred just below middle of nasal, pointing up and back, not touching bottom edge of nasal. Supranasals absent. Rostral broader than deep. Frontonasal broader than long, not separated from frontal by prefrontals meeting in midline. Frontal longer than broad, shorter than frontoparietal and interparietal together, in contact with 2 anteriormost supraoculars. Supraoculars 3, the second is the largest. Frontoparietals distinct, larger than interparietal. A pair of parietals meeting behind interparietal and bordered posteriorly by a pair each of nuchals and temporals, also in contact with interparietal, frontoparietal, third supraocular and 2 postoculars. Loreals 2, anterior one the larger; anterior loreal in contact with first supralabial, posterior loreal, prefrontal, frontonasal and nasal; posterior loreal in contact with second supralabial, first subocular, upper and lower preocular, prefrontal and anterior loreal. Supralabials 7, the sixth is the largest. Infralabials 6, several of them equal in size; fifth supralabial below centre of eye. Mental broader but shallower than rostral. Suboculars 3 and 4 separated by fifth supralabial. Postmental larger than mental. Chinshields 3 pairs. One primary temporal. Dorsal scales similar in size to ventral scales, weakly striate. Ventral scales smooth. Subdigital lamellae smooth. Ear opening round, small with no projecting granules. Forelimbs shorter than hindlimbs. Adpressed limbs not meeting in adult. Digits moderately long, sub-cylindrical. Third front digit shorter than the fourth.

Measurements (in mm; holotype with the variation shown in the type series in parentheses). SVL 58.9 (mean 55.0, range 46.8–67.1), HL 8.0 (mean 7.3, range 6.6–9.0), HW 5.4 (mean 5.4, range 4.8–6.3), AG 34.3 (mean 31.8, range 25.2–42.0), SF 20.3 (mean 20.0, range 16.8–23.2), SE 10.0 (mean 8.8, 7.2–10.6), EF 10.3 (mean 10.9, range 8.3–12.9), and TL 56.2.

Variation (holotype with the variation shown in the type series in parentheses). Upper ciliaries 7 (mean 6, range 5–8); lower ciliaries 10 (mean 9, range 7–10); nuchals 3 pairs (mean 2 pairs, range 0–3 pairs); midbody scale rows 32 (mean 31, range 30–34); ventral scale rows 76 (mean 75, range 70–82); subdigital lamellae 20 (mean 20, range 18–23); supraciliaries 5 (mean 6, range 4–6); suboculars 7 (mean 6, range 6–7). Frontonasal never separated from frontal by prefrontals meeting in midline. Anterior loreal in contact with first or second supralabial. Supralabials 7 (usual) or 8, the sixth or seventh are the largest. Infralabials 6 (usual) or 7. Third front digit as long as (usual) or shorter than the fourth. Maximum SVL 66.2 mm (shrinkage about 5% based on original records). One specimen had an intact tail (TL/SVL = 1.00). Ratios for morphological measurements (± SD): AG/SF 1.60 ± 0.17; SE/EF 0.82 ± 0.09; HL/HW 1.37 ± 0.07. The maximum SVL observed was 65 mm for males and 70 mm for females. Intact TL/SVL = 1.1 (N=18) ( Patterson 1985).

Colouration. Dorsal surface moderate olive to dark olive brown, occasionally black, with irregular flecks. A median dorsal dark grayish brown longitudinal stripe, 2 half-scale rows wide, well or partially developed, commencing behind the head and passing back to the base of the tail. A light brown dorsal band 2 half-scale rows wide with light flecks. Another broken dark brown band, 1 half- to 2 half-scale rows wide, shading on to a pale dorsolateral band 1 half- to 2 half-scale rows wide. A pale dorsolateral band, extending from posterior margin of eye to first one-third of tail. This stripe bordered laterally by a dark brown band usually with notched edges above and below. A broad dark reddish brown lateral band 1.5 to 2.5 scale rows wide, originating at tip of snout, passing through the eye and ending near tip of tail, bordered laterally by a very dark brown broken band and with pale scales extending into it from above and below; sometimes flecked with white. Below this an indistinct pale stripe passes from beneath the anterior border of the eye through the ear, above the limbs to the tail. This stripe is irregularly defined below by brown scales which merge gradually with the yellowish grey ventral colouration. Ventral surface usually speckled with black spots on chin and throat. Outer surface of forelimbs is dark brown with black and white specks. Juvenile colouration similar to adult, but generally lighter. Ear opening round, small, with no projecting granules on anterior margin. There do not appear to be sexually dimorphic colour patterns.

Etymology. Refers to the Burgan Stream area, the type locality for the species. The common name is the Burgan skink.

Habitat and life history. Oligosoma burganae appears to be confined to the Rock and Pillar Ranges ( Figure 5 View FIGURE 5 d) and Lammermoor Ranges (CENTRAL OTAGO: 67.07 Rock and Pillar and LAMMERLAW: 68.02 Waipori; McEwen 1987) of central Otago, and only occurs above 900 m (i.e. a subalpine species). The Rock and Pillar ED consists of sub-continental schist block mountains rising steeply from an altitude of 400–1450 m, with annual rainfall from 500–1700 mm and snow to 1000 m during winter. This area is classified as Environment Q3 ( Leathwick et al. 2003). The predominant vegetation of the area is montane short and tall Chionochloa tussockland, with some scrub, particularly Coprosma and Olearia spp. The Waipori ED consists of peaty uplands of the Lammermoor and Lammerlaw Plataeu (up to 1200m asl), which experience cool, dry or moist subcontintental conditions (annual rainfall 500–1200 mm), with snow down to 900m during winter. Predominant vegetation is similar to the Rock and Pillar Ranges, but with pastoral development for sheep and cattle up to 600 m.

The biology, ecology and life-history of O. burganae have been documented previously in Patterson (1985, 1992). The species becomes sexually mature at 49 mm SVL, and has a maximum litter size of six. Parturition occurs in late January or early February. Some sperm was present in the epididymis from October to March, with a large increase of sperm in January. The average home range size for O. burganae was 13.4 m 2. Specific site defence was noted on several occasions, usually towards other skink species. The preferred microhabitat appeared to be herbs and shrubs rather than rocks and grasses. This microhabitat preference appeared to be the main reason why this species was able to coexist with other similarly-sized skink species ( O. polychroma and O. maccanni ) throughout its range. Like most Oligosoma , O. burganae is a diurnal heliotherm. Its diet consists of a range of invertebrates, particularly spiders, and berries from several shrub species such as snowberry ( Gaultheria depressa ). The climate throughout the species’ range is harsh, where snow may occur at any time of the year. Abdominal fat bodies were noted in many specimens, which increased in size during the summer months, and probably aided the skinks in hibernation during winter. Tails, likewise, were relatively emaciated after the skinks emerged from hibernation in the spring, and became plumper over summer as the skinks increased their fat reserves. A population census from 24 January to 20 February 1983 gave a mean density of one animal per 27 m 2 in the type locality. The survival of O. burganae after a controlled burn-off of an area of tussock grassland was noted by Patterson (1984).

Conservation status. Oligosoma burganae is currently considered At Risk: Declining (B, large population and low to moderate ongoing or predicted decline; with qualifiers Data Poor, and Range Restricted) in the New Zealand Department of Conservation’s national threat classification lists ( Hitchmough et al. 2010). A recent assessment of the Burgan skink population (this study) suggests that there has been a serious population decline in the species since 1985 ( Patterson 1985). Thus, research is needed to identify the current population status and trend, establish the species’ known range, and identify potential threats.