Research Article |
Corresponding author: Alex Slavenko ( alex.slavenko1@gmail.com ) Academic editor: Uwe Fritz
© 2024 Alex Slavenko, Stephen J. Richards, Stephen C. Donnellan, Allen Allison, Paul M. Oliver.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Slavenko A, Richards SJ, Donnellan SC, Allison A, Oliver PM (2024) Gold in the mountains: Striking new species of Papuascincus (Sphenomorphini: Scincidae) from New Guinea. Vertebrate Zoology 74: 133-149. https://doi.org/10.3897/vz.74.e112782
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Abstract
Skinks are the most diverse component of the reptile fauna in the mountains of New Guinea and many seemingly specialised high-elevation species remain undescribed. Here we describe two spectacular new gold-patterned skinks in the montane-specialist genus Papuascincus. Both species can be diagnosed from all congeners by their distinctive colouration, in addition to aspects of scalation and body size. One new species is mainly recorded from lower montane forest in karst habitats spanning more than five hundred kilometres along the southern edge of New Guinea’s Central Cordillera and is likely to warrant an IUCN conservation status of Least Concern. The second new species has thus far only been recorded from cloud forest on the summit of Mt. Menawa in the North Coastal Ranges and we suggest it should be considered Data Deficient. However, if further survey work confirms a restricted distribution with little scope for upslope elevational retreat under future warming climates it will likely qualify for Endangered or Critically Endangered status.
Central Cordillera, elevational endemism, karst, montane forest, North Coastal Mountains, Palaia
New Guinea is the world’s highest and largest tropical island and is also exceptionally biodiverse, with recent work showing it supports the world’s most species-rich insular plant, frog and bird assemblages (
The most species-rich component of New Guinea’s terrestrial vertebrate fauna is the sphenomorphin skinks (
Papuascincus Allison & Greer, 1986 is a genus of moderately small, diurnal and basking skinks that is closely associated with the mountains of New Guinea. At elevations above 2000 m. a.s.l. they are often one of the few reptiles present. This genus is part of the second of the two Melanesian sphenomorphin radiations noted above. The Papuan Peninsula is the likely origin for diversification of this clade, which includes the genera Papuascincus, Lobulia Greer, 1974, Prasinohaema Greer, 1974, Fojia Greer & Simon, 1982, Palaia Slavenko et al., 2021, Alpinoscincus Slavenko et al., 2021, and Nubeoscincus Slavenko et al., 2021. Four species of Papuascincus are currently recognised, but species diversity is considerably underestimated and many undescribed species that vary in body size, colouration, and elevational distribution are known (
Map of sampled localities in this study, with light blue points representing Papuascincus borealis sp. nov. and gold points representing Papuascincus eldorado sp. nov. Circles represent localities where specimens were collected, and squares represent localities where animals were observed and photographed (by Mark O’Shea, Nick Baker and Mattias S Lanas), but not collected. The gold polygon represents an elevational buffer of 700–1600 m a.s.l. along the southern versant of the Central Cordillera, showing the inferred suitable habitat band for Papuascincus eldorado sp. nov.
Material of the new species was collected, euthanised and preserved using standard protocols (as described in
Specimens were sexed by internal examination of the gonads, and deemed adult if the gonads were large and could be identified as either testes or ovaries. Meristic and mensural protocols followed
As in
To assess genetic divergence against published data for Papuascincus (
Golden Mountain Skink
All Papua New Guinea.
A species of Papuascincus characterised by the unique combination of small size (maximum adult SVL 48.6 mm); 2–3 small rounded lobules on anterior edge of ear opening; supralabials seven; scale rows at midbody 24–28; postsuboculars typically two; paravertebral scales 43–50; lamellae under 4th toe 22–29; single supradigital scales on 4th toe 11–14; and dorsal colour pattern on body consisting of three greenish-gold dorsal stripes on a glossy black background; tail gold with scattered black flecks; limbs black with gold flecking.
Photos in life of Papuascincus eldorado sp. nov.: A holotype (
Papuascincus eldorado sp. nov. differs from all other species of Papuascincus in having a dorsal pattern consisting of three light stripes on black background versus two light dorsolateral stripes on light-brown background (P. stanleyanus and P. buergersi), two light dorsolateral stripes and two dark-brown medial stripes on light brown background (P. morokanus), or dark grey-brown blotches on light brown background (Pap. phaeodes). It additionally differs from P. stanleyanus (n = 1) and Pap. buergersi (n = 8) in having smaller adult size (maximum SVL 48.6 mm vs. 57.9 and 60.5, respectively) and a lower count of scale rows at midbody (24–27 vs. 31 and 28–31, respectively), from P. stanleyanus in having a lower count of paravertebral scales (43–50 vs. 64), from P. morokanus (n = 2) in having a higher count of single supradigital scales on 4th toe (11–14 vs. 6–7), and from Pap. phaeodes (n = 1) in having seven supralabials (vs. six), in having 2–3 small rounded lobules on anterior edge of ear opening (vs. 4–5 large, sharply pointed), and in having a much higher count of single supradigital scales on 4th toe (11–14 vs. 2).
In overall colour pattern Pap. eldorado sp. nov. is similar to Palaia pulchra, a species in a monotypic genus that is the sister lineage to the entire radiation of Papuascincus (
Adult male, SVL 44.1 mm; tail regenerated, 60.6 mm total length, 30.4 mm regenerated section; FHD 20.5 mm; BW 8.2 mm; HL 10.6 mm; HW 6.7 mm; HD 5.1 mm; FLL 15.2 mm; HLL 21.0 mm.
Rostral broad and shallow, wider than deep, projecting slightly onto top of snout; nasals more or less rectangular, separated by rostral and frontonasal contact, projecting anterodorsally onto dorsum of snout; nostril circular, centred within nasal, with suture extending posteriorly from anterodorsal edge of nostril to edge of nasal scale; frontonasal large, with eight sides, extending laterally to slightly above level of nares, posteriorly in narrow contact with frontal; prefrontals large, separated by frontonasal and frontal contact, bordered lateroventrally by two loreals; supraoculars four, of which two contact the frontal and three contact the frontoparietal; frontal roughly kite shaped, widest anteriorly; frontoparietal single, anteriorly in narrow contact with frontal, posteriorly in contact with interparietal and parietals; interparietal smaller than fused frontoparietal, kite shaped, widest anteriorly; parietal eye spot absent; parietals in contact behind interparietal, in contact anteriorly with frontoparietal, posteriormost supraocular, and two pretemporals; nuchals in two pairs, transversely enlarged, wider than long, separated from secondary temporal by single intercalated scale.
Anterior loreal slightly smaller than posterior loreal, both higher than long; lower preocular roughly square; upper preocular much smaller than lower preocular, longer than high, separated from prefrontal by anteriormost supraciliary and posterior loreal contact; presubocular single, interdigitated between supralabials; postsuboculars two, lower interdigitated between subocular supralabial and penultimate supralabial; lower eyelid scaly, moveable, with clear palpebral disc roughly size of ear opening; supraciliaries eight, anteriormost not in contact with frontal, posteriormost projecting medially and interdigitated between posteriormost supraocular and upper pretemporal; primary temporal single, interdigitated between posterior two supralabials; secondary temporals two, upper larger and overlapping lower; supralabials seven, fifth in contact with small scales of lower eyelid; postsupralabials two; ear opening moderately large, with three small round lobules along anterior margin.
Mental single; postmental single, contacting two anteriormost infralabials; infralabials six; enlarged chin shields in three pairs, first pair in medial contact, second pair narrowly separated by single medial scale, third pair separated by three medial scales; posteriormost chin shield in contact with penultimate infralabial.
Body scales smooth, in 26 rows at midbody; paravertebral scales 46; medial precloacal scales enlarged, overlapping lateral precloacals.
Scales on dorsal surface of fourth toe in two rows proximally, single row distally beginning midway along proximal phalanx, 14 single scales; subdigital lamellae under fourth toe 27, smooth.
Base dorsal colouration glossy black, overlain with thin, slightly irregular but unbroken white vertebral stripe extending from snout-tip to base of tail, two thinner dorsolateral stripes with small number of narrow breaks, and small number of additional white flecks, especially in posterior half of body. Lateral surfaces of body largely black overlain with series of white mid-lateral flecks and further light ventrolateral mottling. Lateral surfaces of head white with prominent black patch in front of eye, and further extensive black flecking on lips. Ventral surfaces of body light buff, unpatterned. Limbs predominately black on dorsal and lateral surfaces with extensive white mottling, pale areas more extensive on hindlimbs than forelimbs. Ventral surfaces of limbs largely buff, but with scattered black flecks. Digits banded white and black on exposed surfaces, black on palmar and plantar surfaces. Original portions of tail faded yellow on exposed surfaces, buff ventrally, with fading series of black dorsal and lateral flecks extending from base to approximately 30 mm along tail. Regrown section of tail dirty yellow, unpatterned.
Adult body size 37.8–48.6 mm SVL (mean = 43.0, SD = 3.2, n = 15). Males (mean = 43.7, range = 37.8–48.6, SD = 3.5, n = 11) reach larger size than females (mean = 41.7, range = 40.4–43.6, SD = 1.7, n = 4). FHD 16.4–22.4 mm (mean = 20.0, SD = 1.9, n = 15). BW 6.2–8.5 mm SVL (mean = 7.3, SD = 0.8, n = 15). Forelimbs 31.9–38.4% of SVL (mean = 33.9%, SD = 1.8, n = 15). Hindlimbs 42.1–49.5% of SVL (mean = 45.8%, SD = 2.2, n = 15). Scale rows at midbody 24–27 (mean = 25.5, SD = 0.9, n = 17); paravertebral scales 43–50 (mean = 45.6, SD = 1.8, n = 17). Lamellae under 4th toe 22–29 (mean = 24.2, SD = 1.9, n = 17); single supradigital scales on 4th toe 11–14 (mean = 12.5, SD = 1.2, n = 17). Mostly three pairs of nuchals, but
Overall colour pattern is consistent across all specimens, comprising three dorsal stripes on black background on head and body, limbs mottled black and white, and tail yellowish with series of black lateral and dorsal flecks. Some variation in continuity and form of dorsolateral stripes evident, these often broken into series of flecks or blotches or even mottling, especially towards posterior part of body. Considerable variation in how far black flecking extend from the base of the tail, extent ranging between 10–30 mm from the base. Venter typically light buff and unpatterned, occasionally with scattered black flecks under tail and along sides of body. Exposed surfaces of original and regrown tail always dirty yellow.
The following description of colour in life is based on photographs of specimens
Based on analyses of a 708 bp region of the ND4 mitochondrial gene Pap. eldorado sp. nov. is most closely allied (mean p-distance 11.7%) to Papuascincus lineage IV, a slightly larger form (SVL typically between 50–60mm) that occurs at higher elevations in the Central Cordillera (1500–2500 m a.s.l.) (
From the Spanish noun phrase meaning “the golden”, in reference to the species’ distinct golden colouration.
This species is known from numerous sites spanning 500 km along the southern versant of New Guinea’s Central Cordillera, extending from Western Province, in the west through Southern Highlands, Hela and Chimbu Provinces, and as far east as the Bulolo area, Morobe Province. Given its wide range in PNG, it is possible that it also extends further west into Papua Province of Indonesian New Guinea.
All records of Pap. eldorado sp. nov. are from foothill and lower montane forest between 760 and 1600 m a.s.l. Records on the P’nyang Range (Fig.
At most localities in the west of its range this species was collected on karst basement. Due to the very thin soils and complex nature of these landscapes tree cover was in many areas relatively low and quite patchy, with few very large emergent trees (Fig.
Lineages III and IV of Papuascincus (
The populations described herein represent an extent of occurrence of 19,986 km2 and an area of occupancy of 80 km2 (based on occupation of 4 km2 cells; both calculated using http://geocat.kew.org). The species occurs over a wide area, on multiple substrates, and at an elevational band that suggests a considerable scope for upslope retreat as global temperatures rise in coming decades. We therefore recommend assigning an IUCN red list conservation status of Least Concern for Pap. eldorado sp. nov..
A species of Papuascincus characterised by the unique combination of large size (maximum adult SVL 58.2 mm); 2–3 small rounded lobules on anterior edge of ear opening; postsuboculars typically three; scale rows at midbody 26–28; paravertebral scales 46–47; lamellae under 4th toe 20–25; single supradigital scales on 4th toe 14–15; dorsal colour pattern on body consisting of three yellow-gold dorsal stripes on a black background; tail gold with diffuse black speckling not extending more than 10 mm along tail; limbs black with gold flecking.
Papuascincus borealis sp. nov. differs from P. stanleyanus (n = 1), Pap. buergersi (n = 8), P. morokanus (n = 2), and Pap. phaeodes (n = 1) in having a dorsal pattern consisting of three light stripes on black background versus two light dorsolateral stripes on light brown background (P. stanleyanus and Pap. buergersi), two light dorsolateral stripes and two dark brown medial stripes on light brown background (P. morokanus), or dark grey-brown blotches on light brown background (Pap. phaeodes). It additionally differs from from P. stanleyanus and Pap. buergersi in having a lower count of scale rows at midbody (26–28 vs. 31 and 28–31, respectively), from P. stanleyanus in having a lower count of paravertebral scales (46–47 vs. 64), from P. morokanus and Pap. phaeodes in achieving larger adult size (maximum SVL 58.2 mm vs. 45.6 and 44.5, respectively), from P. morokanus in having a higher count of single supradigital scales on 4th toe (14–15 vs. 6–7), and from Pap. phaeodes in having 2–3 small rounded lobules on anterior edge of ear opening (vs. 4–5 large, sharply pointed), and in having a much higher count of single supradigital scales on 4th toe (14–15 vs. 2).
In overall colour pattern Papuascincus borealis sp. nov. is most similar to Palaia pulchra and Pap. eldorado sp. nov., from which it differs in having larger adult size (maximum SVL 58.2 mm vs. versus 40.8 and 48.6, respectively). It further differs from Pal. pulchra in having sutured nasal scale (vs. unsutured; see
Ovigerous adult female, SVL 56.2 mm; tail regenerated, 81.5 mm total length, 16.2 mm regenerated section; FHD 28.9 mm; BW 10.4 mm; HL 12.6 mm; HW 7.8 mm; HD 6.0 mm; FLL 19.4 mm; HLL 25.5 mm; two eggs in abdomen.
Rostral broad and shallow, wider than deep, projecting slightly onto top of snout; nasals more or less rectangular, separated by rostral and frontonasal contact, projecting anterodorsally onto dorsum of snout; nostril circular, centred within nasal, with suture extending posteriorly from anterodorsal edge of nostril to edge of nasal scale; frontonasal large, with seven sides, extending laterally to slightly above level of nares, posteriorly in narrow contact with frontal; prefrontals large, in narrow medial contact, bordered lateroventrally by two loreals; supraoculars four, of which two contact the frontal, and three contact the frontoparietal; frontal roughly kite shaped, widest anteriorly; frontoparietal single, anteriorly in narrow contact with frontal, posteriorly with interparietal and parietals; interparietal smaller than fused frontoparietal, kite shaped, widest anteriorly; parietal eye spot absent; parietals in contact behind interparietal, in contact anteriorly with frontoparietal, posteriormost supraocular, and two pretemporals; nuchals in four pairs, transversely enlarged, wider than long, separated from secondary temporal by a single intercalated scale.
Anterior loreal slightly smaller than posterior loreal, both higher than long; lower preocular roughly square in shape; upper preocular much smaller, longer than high, separated from prefrontal by anteriormost supraciliary and posterior loreal contact; presubocular single, abutting supralabials; postsuboculars three, lowest interdigitated between subocular supralabial and penultimate supralabial; lower eyelid scaly, moveable, with clear palpebral disc roughly size of ear opening; supraciliaries eight, anteriormost in narrow contact with frontal, posteriormost projecting medially and interdigitated between posteriormost supraocular and upper pretemporal; primary temporal single, interdigitated between posterior two supralabials; secondary temporals two, upper larger and overlapping lower; supralabials seven, fifth in contact with small scales of lower eyelid; postsupralabials two; ear opening moderately large, with three small round lobules along anterior margin.
Mental single; postmental single, contacting two anteriormost infralabials; infralabials six; enlarged chin shields in three pairs, first pair in medial contact, second pair narrowly separated by single medial scale, third pair separated by three medial scales; posteriormost chin shield in contact with penultimate infralabial.
Body scales smooth, in 28 rows at midbody; paravertebral scales 46; medial precloacal scales enlarged, overlapping lateral precloacals.
Scales on dorsal surface of fourth toe in two rows proximally, single row distally beginning midway along proximal phalanx, 14 single scales; subdigital lamellae under fourth toe 23, smooth.
Base dorsal colouration black, with a narrow unbroken yellow vertebral stripe extending from snout-tip to base of tail, two narrower unbroken yellow dorsolateral stripes, and small number of additional yellow flecks between vertebral and dorsolateral stripes, forming faded stripes on posterior half of body. Lateral surfaces of body largely black overlain with series of yellow mid-lateral flecks and additional pale ventrolateral mottling. Lateral surfaces of head with diffuse black and yellow mottling, and prominent yellow canthal stripe. Body venter light buff, unpatterned. Limbs black on dorsal and lateral surfaces with extensive yellow mottling. Ventral surfaces of limbs buff. Digits banded white and black on exposed surfaces, black on palmar and plantar surfaces. Original portions of tail faded yellow on exposed surfaces, buff ventrally, with few black dorsal and lateral flecks extending from base to approximately 10 mm along tail. Regrown section of tail dirty yellow, unpatterned.
Adult body size 53.8–58.2 mm SVL (mean = 55.7, SD = 2.0, n = 4). FHD 25.3–28.9 mm (mean = 26.7, SD = 1.5, n = 4). BW 8.9–10.3 mm (mean = 9.6, SD = 0.6, n = 4). Forelimbs 32.4–34.5% of SVL (mean = 33.5%, SD = 0.9, n = 4). Hindlimbs 40.6–45.4% of SVL (mean = 43.0%, SD = 2.0, n = 4). Scale rows at midbody 26–28 (mean = 27, SD = 1.15, n = 4); paravertebral scales 46–47 (mean = 46.25, SD = 0.5, n = 4). Lamellae under 4th toe 20–25 (mean = 23, SD = 2.2, n = 4); single supradigital scales on 4th toe 14–15 (mean = 14.25, SD = 0.5, n = 4).
Overall colour pattern highly consistent across all specimens, always including three dorsal stripes on black background on head and body, limbs mottled black and yellow, and tail yellowish with minimal black lateral and dorsal flecks. Some variation in continuity and form of yellow flecks along posterior of dorsum between vertebral stripe and dorso-lateral stripes, often, but not always, forming indistinct stripes extending to base of tail. Venter always light buff, unpatterned. Exposed surfaces of original and regrown tail always dirty yellow.
The following description of colour in life is based on photographs of specimens
Based on analyses of a 708 bp region of the ND4 mitochondrial gene Pap. borealis sp. nov. is deeply divergent from all other sampled Papuascincus (minimum p-distance 14.4% being to Papuascincus eldorado sp. nov., and other taxa being more divergent). The within-species p-distance was 0.4%.
Masculine Latin adjective meaning “northern”, in reference to the species’ distribution on the Bewani Mountains, the most northerly location of any known species of Papuascincus.
Only known from the summit of Mt. Menawa (~1950m a.s.l.), in the Bewani mountains on the northern versant of New Guinea. This is the only species of Papuascincus known to occur on the North Coastal Ranges (excluding the Huon Peninsula).
Mt. Menawa is an isolated mountain and the highest peak in the otherwise low-lying Bewani Range and was originally covered in cloud forest, with stands of Nothofagus grandis and Lithocarpus sp. prominent on the adjoining ridges (Fig.
Pap. borealis sp. nov. was observed basking ca. 50 cm above the ground on the base of a tree stump and on other similarly raised perches suggesting that it may be partially arboreal. It appeared to be uncommon. The ground skink Emoia irianensis Brown, 1991 was also found on the summit. It was previously known only from montane areas at the western end of the Central Cordillera (1200–2000 m a.s.l.). We observed E. irianensis basking in open areas within a prostrate species of Vaccinium and it appeared to be uncommon. The occurrence of E. irianensis on Mt. Menawa suggests that there have been dispersal pathways between the Bewani Mountains and the mountains of north-east Indonesian New Guinea. This area of Indonesian New Guinea remains poorly known and Papuascincus borealis sp. nov. may also occur there.
Population size and trend unknown. The four specimens are only known from a single location, with an area of occupancy of a single 4 km2 cell. The true extent of the species’ distribution in the Bewani mountains, and potentially in the other peaks in the Torricelli mountains or even the Cyclops and Foja mountains (in Indonesia) needs to be determined. Repeated surveys will also be needed on Mt. Menawa - since the 1980s, a network of roads has been constructed in the lowlands north of the Bewani Mountains and extensive areas of forest have been cleared for oil palm. If, as is likely, these developments facilitate logging that extends into the Bewani Mountains, this may adversely impact the only known population of Pap. borealis sp. nov. If further survey work confirms a restricted distribution with little scope for upslope elevational retreat under future warming climates it will likely qualify for Endangered or Critically Endangered. In the absence of good survey data we recommend assigning a status of Data Deficient to Pap. borealis sp. nov.
Papuascincus eldorado sp. nov. and Pap. borealis sp. nov. share a similar colour pattern of three gold dorsal stripes on a black background. This pattern is atypical for Papuascincus, which are generally less brightly coloured with fewer dorsal stripes (with the exception of P. morokanus). These colour patterns are, however, similar to Palaia pulchra (Fig.
Pap. eldorado sp. nov. occurs at elevations (700–1300 m a.s.l.) lower than is typical for most species of Papuascincus, which have elevational distributions centred above 1500 m. a.s.l. (
Maximum Likelihood phylogenetic reconstruction of Papuascincus based on a 708 bp region of the ND4 mitochondrial gene. Filled circles represent nodes with a bootstrap (BS) value of 100%, empty circles represent nodes with BS values between 80% and 100%, and no circles represent unsupported nodes (BS < 80%). Clade labels for the different lineages of Papuascincus follow
Pap. borealis sp. nov. is currently the only species of Papuascincus known from the North Coastal Ranges. Recent systematic and phylogenetic work has revealed several instances of putative or confirmed sister lineages distributed across seemingly isolated montane (> 1000 m) habitats in the North Coastal Ranges and the Central Cordillera (Cyrtodactylus boreoclivus Oliver, Krey, Mumpuni & Richards, 2011 and Cyrtodactylus medioclivus Oliver, Richards & Sistrom, 2012:
We are grateful to Glenn M. Shea for generously providing photographs and measurements of the type specimens of Papuascincus buergersi and Papuascincus phaeodes. Glenn M. Shea, Simon Maddock, and Ishan Agarwal provided excellent feedback on a previous version of this manuscript. We thank Mark O’Shea, Nick Baker, and Mattias S Lanas for sharing photographs, coordinates, and natural history data of Papuascincus eldorado sp. nov. encountered in the field, Janne Torkkola for generating sequence data for the new species, and Katie Date, Karen Roberts, Kylea Tink, Andrew Amey and Ralph Foster for providing access to specimens in their care and other logistic support. Field work in Western Province was supported by ExxonMobil PNG (EMPNG), and in Hela Province by EMPNG and World Wide Fund for Nature. Our work in Papua New Guinea was approved by the PNG National Research Institute (NRI), and export permits were approved by the Department of Environment and Conservation (DEC; now Conservation and Environment Protection Authority). We are most grateful to the late Jim Robins and to Georgia Kaipu (NRI) and the late Barnabas Wilmott (DEC) for their assistance. Numerous other researchers and landholders provided access permissions, logistic support and advice during fieldwork in PNG and we also thank them for their support. This is Contribution No. 2023-006 to Bishop Museum’s Pacific Biological Survey.
Appendix 1
Data type: .docx
Explanation notes: Comparative material examined for this study.
Appendix 2
Data type: .xlsx
Explanation notes: Information on the specimens used in this study, including morphological measurements and related GenBank accession numbers for newly generated sequences.
Appendix 3
Data type: .tre
Explanation notes: Rooted maximum likelihood phylogeny in Nexus format with bootstrap values.