Papuascincus borealis, Slavenko & Richards & Donnellan & Allison & Oliver, 2024

Slavenko, Alex, Richards, Stephen J., Donnellan, Stephen C., Allison, Allen & Oliver, Paul M., 2024, Gold in the mountains: Striking new species of Papuascincus (Sphenomorphini: Scincidae) from New Guinea, Vertebrate Zoology 74, pp. 133-149 : 133

Papuascincus borealis sp. nov.

Figures 4 , 5 , 6

Holotype.

BPBM 23059 (field number AA 11963; GenBank number OR837029), ovigerous adult female with two eggs, at summit of Mt. Menawa, approximately 10.5 km N and 15.7 km E of Utai, Bewani Mountains, Sandaun (West Sepik) Province, Papua New Guinea (3.295°S, 141.723°E, 1950 m a.s.l.), collected by A. Allison on 19 October 1986.

Paratypes (n = 3).

BPBM 23016, 23060, 23061 (GenBank number OR837028) (three adult males), same locality and collection data as holotype.

Diagnosis.

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.

Comparisons.

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 Slavenko et al. 2022), tail gold in life (vs. orange), white lateral stripe absent (vs. present), and limbs overall black with gold mottling (vs. orange with black mottling). It further differs from Pap. eldorado sp. nov. in having modally three postsuboculars (vs. two), a less distinct yellow canthal stripe, face densely patterned with diffuse and extensive black areas (vs. distinct glossy black blotching and flecking on a light background; Figs 2C , 5C ), dorsal stripes grading from gold to yellow (vs greenish-yellow to yellow; Figs 3 , 6 ), and tail of adults with diffuse black speckling not extending more than 10 mm along tail (vs. tail with clear black flecks extending up to 30 mm along tail; Figs 2A , 5A ).

Description of holotype.

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.

Colouration in preservative.

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.

Variation in the type series.

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). BPBM 23016 with three pairs of nuchals, BPBM 23060 with two nuchals on left side and four on right, BPBM 23061 with three nuchals on left side and two on right. Primary nuchals usually separated from secondary temporals by single smaller intercalated scale, but BPBM 23060 has two on left side and one on right. Prefrontals either separated by frontonasal and frontal contact (n = 2) or in narrow medial contact (n = 2). Supracilliaries either seven (n = 2) or eight (n = 2). Anteriormost supraciliary in narrow contact with frontal in all but BPBM 23060 where it is separated. Postsuboculars typically three (n = 3), occasionally two (BPBM 23016). Pretemporals typically two, occasionally one (BPBM 23060). Supralabials typically seven (n = 3), occasionally six (BPBM 23016).

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.

Colouration in life.

The following description of colour in life is based on photographs of specimens BPBM 23016, 23059, and 23061 (Fig. 6 ). Base colouration of dorsum glossy black, light patterning on head and body typically transitions from glossy golden-yellow on head and upper body to gold on posterior body and tail.

Genetic comparisons.

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%.

Etymology.

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 .

Distribution.

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).

Natural history.

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. 4B-C ). The summit was cleared some years prior to collection of the type series to create a helicopter landing area to support the installation of a small solar-powered repeater for Papua New Guinea’s radio-telephone system along the border with Indonesia. The landing area was being encroached on by an assemblage of early succession montane shrubs and trees including Homalanthus novoguinensis , Melicope elleryana , Alphitonia incana , and Caldcluvia sp., together with gingers ( Alpinia spp.), and a pitcher plant ( Nepenthes sp.). Two species of successional ferns, Diplopterygium and Dipteris , were common in open areas as was a prostrate species of Vaccinium .

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.

Suggested IUCN status.

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.

Figures

Figure 2. Papuascincus eldorado sp. nov. holotype (QM J 97880); A dorsal view, B ventral view, C lateral view of head, D dorsal view of head, and E ventral view of head. Images by Alex Slavenko.

Figure 3. Photos in life of Papuascincus eldorado sp. nov.: A holotype (QM J 97880) from P'nyang, Western Province; B paratype (BPBM 21669) from Aseki, Morobe Province; C paratype (SAMA R. 71758) from Benaria, Hela Province; D paratype (SAMA R. 57046) from Gobe, Southern Highlands Province; E - F uncollected specimen from Moran, Hela Province. Image A by Paul M. Oliver, image B by Allen Allison, images C and D by Stephen J. Richards, images E and F by Mark O'Shea.

Figure 4. Habitat photos of (A) P'nyang, type locality for Papuascincus eldorado sp. nov., and (B - C) summit of Mt. Menawa, type locality for Papuascincus borealis sp. nov. Image A by Paul M. Oliver, images B and C by Allen Allison.

Figure 5. Papuascincus borealis sp. nov. holotype (BPBM 23059); A dorsal view, B ventral view, C lateral view of head, D dorsal view of head, and E ventral view of head. Images by Alex Slavenko.

Figure 6. Photos in life of Papuascincus borealis sp. nov.: A holotype (BPBM 23059); B paratype (BPBM 23061); C paratype (BPBM 23016), all from Mt. Menawa, Sandaun (Sepik) Province. Images by Allen Allison.