Saproscincus saltus, Hoskin, 2013

Hoskin, Conrad J., 2013, A new skink (Scincidae: Saproscincus) from rocky rainforest habitat on Cape Melville, north-east Australia, Zootaxa 3722 (3), pp. 385-395 : 388-392

Saproscincus saltus sp. nov.

Cape Melville Shade Skink

( Figs 2 , 3 , 4A , 5 )

Material examined. Holotype: QMJ 92572, Melville Range (14°16'38" S, 144°29'28" E, elevation 500 m), Cape Melville, north-east Queensland, C. J. Hoskin, 20 March 2013 . Paratypes: QMJ 92561, QMJ 92562 , collection details as for holotype.

Diagnosis. Saproscincus saltus sp. nov. is diagnosed from congeners by the following combination of characters: moderate body size (SVL 38.4–42.9 mm), long limbs (L1/SVL 32.3–33.8%, L2/SVL 45.5–46.3%), long digits (4 th finger/SVL 7.3–7.6%, 4 th toe/SVL 10.5–12.2%), flattened head (HD/SVL 8.2–9.0%), 22–26 lamellae under 4 th toe, 23–24 midbody scales, 52–55 paravertebral scales, and parietal scales each bordered by a single nuchal and two temporal scales (i.e., 6 scales contacting posterior margin of parietal scales). The golden dorsal colour with dark flanks is also diagnostic ( Figs 3 , 4A ).

Etymology. saltus ; from the Latin for leaping. In recognition of the agility of this species across boulders. The species epithet is treated as a noun in apposition.

Measurements and scale counts of holotype ( Fig. 5 ). SVL = 38.4 mm, AG = 19.8 mm, midBW = 6.0 mm, TL (regenerated) = 46.9 mm, L1 = 12.5 mm, FLL = 5.1 mm, 4 th finger length = 2.8 mm, L2 = 17.5 mm, HLL = 6.4 mm, 4 th toe length = 4.5 mm, HL = 8.0 mm, HW = 5.3 mm, HD = 3.5 mm, snout = 3.2 mm, EE = 2.9 mm, NL = 6.7 mm, midbody scale rows = 24, paravertebrals = 53, ventrals = 54, lamellae 4 th toe = 24, lamellae 4 th finger = 17, supralabials = 7, infralabials = 6, supraciliaries = 7.

Description of type series. Data presented as range followed by mean in brackets. Adult measurements (mm): SVL = 38.4–42.9 (40.2), AG = 19.8–21.7 (20.9), midBW = 5.2–6.0 (5.6), Tail (regenerated) = 46.9 (holotype only; paratypes no tails), L1 = 12.5–14.5 (13.2), FLL = 5.0–5.2 (5.1), 4 th finger length = 7.3–7.6 (7.5), L2 = 17.5–19.9 (18.4), HLL = 6.0–7.3 (6.6), 4 th toe length = 10.5–12.2 (11.4), HL = 8.0–9.0 (8.4), HW = 5.0–5.7 (5.3), HD = 8.2–9.0 (8.7), snout = 3.2–3.9 (3.6), EE = 2.9–3.4 (3.1), NL = 6.7–7.4 (7.2). Adult proportions (as % SVL): AG = 50.5–54.1 (52.0), midBW = 12.9–15.7 (13.9), Tail (regenerated) = 122.2, L1 = 32.3–33.8 (32.9), FLL = 12.2–13.3 (12.7), L2 = 45.5–46.3 (45.8), HLL = 15.2–17.1 (16.3), HL = 20.8–21.0 (20.9), HW = 12.7–13.9 (13.3), snout = 8.3–9.2 (8.9), EE = 7.3–7.9 (7.6), NL = 17.2–18.9 (17.9) ( Table 1). Body slender. Head distinct from body due to slight narrowing at neck. Snout rounded in profile. Limbs long and slender; five fingers; five toes. Scalation: Dorsal scales smooth, some with faint indication of 2 or 3 grooves; posterior edge broadly curved. Nasals widely spaced, rostral and frontonasal in broad contact; prefrontals moderately to widely separated; frontal contacting frontonasal, prefrontals, first two supraoculars and frontoparietals; supraoculars 4, second the largest; supraciliaries 6–7 (mean 6.7), first the largest; frontoparietals paired and distinct from interparietal; nuchals contacting parietals 2, typically both in obvious contact but in the holotype one is only in point contact; temporals contacting parietals 4 (i.e., 2 contacting each parietal scale), all in broad contact (see Methods for comment on nuchals versus temporal scales); loreals 2; preoculars 1–2 (mean 1.3), the lower being the largest in the case where there are 2; presuboculars 2, the first being the largest; presupraoculars 1–2 (mean 1.7); supralabials 6–7 (mean 6.3); second supralabial not in contact with lower preocular scales; infralabials 5–6 (mean 5.3); postmental contacting 2 infralabials on each side; palpebral disc moderate, half the size of lower eyelid; ear opening round and large, about half the size of eye; midbody scale rows 23–24 (mean 23.3); ventrals 48–54 (mean 50.3); paravertebrals 52–55 (mean 53.3); lamellae under 4 th finger 17–18 (mean 17.3), with a medial groove on distal portion; lamellae under 4 th toe 22–26 (mean 24.0), with a medial groove on distal portion. Colour pattern in preservative ( Fig. 5 ): Dorsal base colour even golden brown, or with scattered dark flecks and pale dots. Head: Brown or rusty brown on top with dark flecks; labials pale with a smudged grey spot on each scale (giving a barred impression); thin dark line from tip of nose to front of eye, continuing as a broader, brown band down the neck that continues from the forelimbs as the dark flank colour. Body: Flanks brown (darker in the upper flank) with regular pale spots and scattered darker flecks; red mites obvious in axillary region. Dorsum even golden brown, or with scattered dark flecks and pale dots. Original tail (only basal portion on type series): Brown with sparsely scattered dark flecks and pale dots. Regenerated tail (holotype): Light brown with brown flecks down lateral margins. Limbs and digits: Brown, heavily spotted with dark and pale dots. Ventral surfaces: creamy yellow, each scale smudged with a pale grey spot; underside of hands and feet grey; underside of regenerated tail creamy white.

Colour pattern in life ( Figs 3 , 4A ). Dorsal colour gold, with scattered black flecks; top of head golden brown with black flecks and mottling. Flanks brown to dark brown (typically darker on upper flank) with regular golden, yellowish or pale spots. Prominent yellow spot on posterior base of hindlimb, and smaller, less prominent yellow dot on upper base of forelimb. Typically many bright red mites in axillary region. Limbs brown to dark brown with fine pale spots. Side of neck dark, typically with several, irregular pale bands. Lips pale, each scale smudged grey. Thin brown line from front of eye to tip of nose. Iris copper. Original tail golden, with dark smudging and yellow dots; regenerated tail tawny, with dark flecks. Ventral surfaces creamy yellow, each scale smudged with a grey spot; underside of hands and feet dark grey.

Comparison with similar species. Saproscincus saltus sp. nov. can be distinguished from congeners by its long limbs and digits, and its unique colouration of golden dorsum and dark flanks with golden spots. In more detail the following traits distinguish S. saltus sp. nov. from congeners. It is assigned to the ‘northern’ group of Saproscincus ( S. basiliscus , S. lewisi , S. tetradactylus , S. czechurai , S. hannahae ) by the fact that each parietal scale is bordered by a single nuchal and two temporal scales (i.e., typically 6 scales contacting posterior margin of parietal scales) ( Fig. 2 ). In all other Saproscincus species each parietal scale is bordered by a single nuchal and temporal scale (i.e., typically 4 scales contacting posterior margin of parietal scales). Saproscincus saltus sp. nov. can be distinguished from S. tetradactylus by having 5 fingers (vs 4). Saproscincus saltus sp. nov. can be distinguished from S. czechurai and S. hannahae by larger size (max SVL 42.9 mm vs 34 mm for S. czechurai and 38.4 mm for S. hannahae ), longer limbs (L2/SVL 45.5–46.3% vs 27–35% for S. czechurai and 34–45.5% for S. hannahae ), more 4 th toe lamellae (22–26 vs 15–19 for S. czechurai and 16–22 for S. hannahae ), and golden dorsum (vs brown for S. czechurai and S. hannahae ).

Saproscincus saltus sp. nov. is most similar to S. lewisi and S. basiliscus ( Fig. 4 ). Distinguished from S. lewisi by longer limbs and digits (non-overlapping ranges for L1/SVL, FLL/SVL, 4 th finger/SVL, L2/SVL, HLL/SVL, 4 th toe/SVL; Table 1), flatter head (HD/SVL 8.2–9.0% vs 9.3–9.9%), more 4 th toe lamellae (mean 24 vs 21), and more paravertebral scales (52–55 vs 46–50) ( Table1). Distinguished from S. basiliscus by smaller size (mean SVL 40.2 mm vs 42.4 mm), longer limbs and digits (non-overlapping ranges for 4 th finger/SVL, L2/SVL, HLL/SVL; nearly non-overlapping ranges for L1/SVL, FLL/SVL, 4 th toe/SVL; Table 1), flatter head (HD/SVL 8.2–9.0% vs 9.2– 11.0%), more 4 th toe lamellae (mean 24 vs 21), and fewer midbody scale rows (mean 23 vs 26) ( Table1). Saproscincus saltus sp. nov. is further distinguished from S. lewisi and S. basiliscus by its golden dorsum (vs shades of brown) and dark flanks with golden spots (vs typically shades of brown, sometimes dark upper flanks, without golden spots) ( Fig. 4 ). Saproscincus saltus sp. nov. is the only Saproscincus known to occur at Cape Melville.

Genetics. For a 900 base pair sequence of the ND4 region of mtDNA, S. saltus sp. nov. is most closely related to S. basiliscus and S. lewisi but is highly divergent from both at approximately 19.5% and 20.5% divergence, respectively (Hoskin, unpub. data). ND4 sequences for two individuals are deposited on GenBank (QMJ92561 = KF704365 , QMJ92562 = KF704366 ).

Distribution. Known only from the vicinity of the type locality in the uplands of the Melville Range, Cape Melville, north-east Australia ( Fig. 1 ).

Habitat and habits. Found in upland boulder habitat associated with rainforest ( Fig. 6 ). Two individuals were found on mossy boulders under a rainforest canopy ( Fig. 6B ), and one individual was found on exposed boulderfield immediately adjacent to rainforest. All three individuals were found active in the day on boulders. They moved rapidly across the rocks and leapt between boulders when pursued. The type locality is on a ridge that clearly receives plenty of moisture from cloud intercept. The only other skink found at the type locality was Glaphyromorphus fuscicaudis ( Greer 1979) , which was common in thick leaf-litter around the base of boulders. Searches in nearby upland rainforest that was less rocky failed to find S. saltus sp. nov.. Carlia rubrigularis Ingram & Covacevich 1989 and C. longipes ( Macleay 1877) were common in these areas. Eulamprus brachysoma ( Lönnberg & Andersson 1915) occurred in nearby areas of rock amongst rainforest that appeared noticeably drier than at the S. saltus sp. nov. site, while C. fuhni was the only skink found on the exposed boulder-fields away from forest cover.

Figures

FIGURE 1. Map of north-east Queensland, showing Cape Melville and the northern Wet Tropics region, and the Saproscincus present in each of these areas. McIlwraith Range is also shown. The inset shows Australia. Background image is from Google Maps (Imagery 2013 NASA, Map data 2013 GBRMPA, Google).

FIGURE 2. In S. saltus (QMJ92562 depicted here) and other species in the ‘northern’ group of Saproscincus, typically three scales contact the posterior margin of each parietal (P) scale. These scales are defined as a single nuchal (N) and two temporal (T) scales. This gives a total of six scales contacting the posterior margin of the parietal scales.

FIGURE 3. Saproscincus saltus sp. nov. in life: (A, B) holotype QMJ92572, (C) paratype QMJ92562.

FIGURE 4. Comparison of: (A) S. saltus sp. nov. (QMJ92562), (B) S. lewisi (Shiptons Flat), and (C) S. basiliscus (Curtain Fig NP). Photos B and C courtesy of Steve Wilson.

FIGURE 5. Holotype of S. saltus sp. nov. (QMJ92572): (A) dorsolateral, (B) ventral.

FIGURE 6. Habitat of S. saltus sp. nov., Melville Range. (A) shows the edge of the rainforest plateau and the extensive boulder-fields that characterize Cape Melville. (B) shows the rocky rainforest at the type locality.