Carlia caesius, Zug, George R. & Allison, Allen, 2006

Zug, George R. & Allison, Allen, 2006, New Carlia fusca complex lizards (Reptilia: Squamata: Scincidae) from New Guinea, Papua­Indonesia, Zootaxa 1237, pp. 27-44 : 28-34

Carlia caesius n. sp.

( Fig. 1 )

Type material

Holotype. MZB AA 15323, adult male from Indonesia, Papua Province [Freeport Project Area], Timika [4.5417°S 136.8908°E], collected by Allen Allison, 15 March 1997. Paratypes. BPBM 21157 (photographed), 21210, 21217–21221, 21223–21226, 21229–21231, 21233–21234, 21236–21242, 21244, 21249, 21256, 21258, 21260, 21262–63, 21267 (photographed), same locality as holotype but collected from 9–19 March 1997; BPBM 21159, 21161, 21163, 21166–67, 21169, 21176, 21179–21182, Mile 38 camp, ca. 15 km (by air) NNE Timika Airport [4.3944°S 136.9325°E]; BPBM 21206, site 3, ca. 14 mi (by air) S Timika Airport [4.6619°S 136.897°E]; BPBM 21187, site 4, east levee of Minajerwi River, ca. 18.5 km (by air) SSE Timika Airport [4.683°S 136.981°E]. IRSNB 2591–2609, Agats [5° 33’S 138° 08’E]. RMNH 30381, 30568–569, 30571, 30579, 30581, Gariau, aan het Jamoer meer [3° 42’S 134° 56’ E]. USNM 562964–966, same data as holotype except collected on 18 March 1997. ZMB 58578, Unipo [3° 29’S 135° 44’E], ca. 30 km SE Nabire.

Diagnosis

Carlia caesius is a member of the C. fusca complex and differs from all other complex members by the bright blue coloration of head and neck of adult males. Additionally, C. caesius averages (adult females mean 50 mm, adult males 52 mm SVL) smaller than C. ailanpalai , C. beccarii , C. eothen , and C. luctuosa , C. pulla , and larger than C. aramia , C. babarensis , C. leucotaenia , and C. tutela . C. caesius has fewer average Dorsals (46) than the similar sized C. fusca , C. leucotaenia , and C. mysi (48).

Description of holotype

An adult male, 61.9 mm SVL, 85.5 mm tail length (21 mm tip regenerated), 26.9 mm TrunkL, 31.1 mm HindlL, 14.8 mm HeadL, 2.2 mm PalpbD, and 1.9 mm EarD. Scalation right side for bilateral traits: interparietal separate, prefrontals not touching, 4 Supoc, 8 Supcil, 9 Eyeld, 4 Temp, 2 Lor, 7 Suplab, 5th BlwEye, 6 Inflab, round ear­opening, 1 AuricN on anterior border, 44 tricarinate Dorsal (anteriormost bilateral pair enlarged as nuchals), 32 Midbody, 22 smooth 3FingL (slight clefting of few subterminal lamellae), 25 4ToeL, and precloacal scale slightly enlarged. Coloration in life: strikingly two­toned lizard; dorsally and laterally head and neck turquoise ground color muted by black edging on all scales, irregular edged black lateral band from cheek to anterior axilla, dorsolaterally a narrow white stripe from eye to axilla, ventrally turquoise ground color shifts to light blue with persistence of black scale­edging although narrower; at axilla and forelimbs abrupt shift to bright reddish orange ground color, muted dorsally by black edging on scales, edging nearly disappears laterally, dorsally light spots greenish yellow; limbs above and below uniform reddish orange; ventrally chest onto to tail beige with orangish tint.

Coloration in preservative: Dorsally head dark brown, speckled with black and turquoise; neck similar but black restricted to scale margins; rest of dorsum golden brown with black speckling and a few scattered light brown spots; upper parts of tail similar but without light brown spots and with less black than rest of dorsum; dorsolaterally, bluish, discontinuous line from eye to shoulder, face and neck mostly black and speckled with turquoise, especially towards venter and distinct series of black lines extend posteroventrally from lower labials to directly below ear; rest of flanks and anterolateral surface of tail light brown; chin and throat light black suffused with blue, with darker black blotches on chin, and series of longitudinal black lines along throat and neck; rest of venter whitish suffused with yellowish tinge and indistinct blue­black streaks on proximal margins of scales.

Description. A moderate­sized Carlia ranging in adult size from 45 to 65 mm SVL (females 45.1–55.2 mm; males 45.7–64.5 mm) with HeadL 9.9–13.0 mm (females) 10.8–15.9 mm (males), PalpbD 1.0– 1.8 mm (females) 1.3–2.2 mm (males), EarD 1.0–2.0 mm (females) 1.2–2.0 mm (males), TrunkL 18.8–27.0 mm (females) 18.6–31.4 mm (males), and HndlL 19.6–29.5 mm (females) 22.2–32.7 mm (males). Some populations sexually dimorphic in one or more of the following traits: SVL, HeadL, PalpbD, EarD, TrunkL, HndlL, and Dorsal. Head and nuchal scales smooth; interparietal rarely absent; 4 (rarely 5 or 6) Supoc, 7–10 Supcil, 6–12 Eyeld, 7 (rarely 6) Suplab, 5th (rarely 4th) BlwEye, and 6 (uncommonly 5, 7, or 8) Inflab on each side. Ear opening oblong vertical to oblique with 1–5 (commonly 3) AuricN, usually pointed, on anterior and dorsal margin. Trunk scales smooth to weakly tricarinate dorsally and laterally, occasionally strongly tricarinate in males, rarely in females, with 42–50 Dorsal, 31–36 Midbody. Subdigital lamellae smooth, mostly 32 4ToeL.

Coloration is summarized in the subsequent Intraspecific Variations section.

Distribution Southern New Guinea lowlands and mid­elevation mountainside from Etna Bay eastward to and including the Eilanden River basin ( Fig. 5 ).

Etymology

The specific name derives from the Latin caesius for bluish­gray or sea blue in reference to the color of the throat and chin. It is proposed as a noun in apposition.

Intraspecific variation

Samples are available from 6 areas (Bayum to Gariau) extending from 135° E to 138° 30’ E. This sampling spans more than 400 km of diverse lowland and low to mid­elevation montane habitats. Three samples (Agats, Freeport, Gariau) have 8 or more adult females and males each, and these samples show sexual dimorphism (Students’ t tests, p= 0.05) in many mensural traits occasionally in scalation ones ( Table 1 ). The Agats sample is dimorphic in all the mensural traits ( Table 1 ) but in no scalation ones. The Freeport and Gariau samples show dimorphism in some mensural traits and scalation (Dorsal for both, Midbody in only Gariau). In all dimorphic mensural features, males are the larger sex. There is always a question of whether sexual dimorphism actually exists when differences between the means are small. Perhaps, the dimorphism is a statistical artifact resulting from small and/or unequal representation in the samples, or the vagaries of field collecting. The Freeport sample highlights this uncertainty. It contains a few adults (10%) that have strikingly well­developed keels on their tricarinate scales (dorsally and laterally on trunk) in contrast to the weakly tricarinate keeling or absence of keels on most of the Freeport C. caesius and other Carlia fusca complex populations. These strongly keeled individuals are predominantly males (approx. 80%) and importantly the largest individuals of the entire Freeport sample. If they are included in the Students’ t analysis, the Freeport sample (n = 49) is statistically sexually dimorphic in SVL, but if they are excluded (n = 44), females and males are subequal SVL. The strongly tricarinate individuals are not more or less brightly colored than the weakly keeled ones.

As is common in other fusca complex species, Carlia caesius displays low intra­ and inter­locality variation in mensural and scalation traits. The range, minimum, and maximum values are very similar, often identical, between localities. Overall, variation within the Freeport area sample encompasses that of the other C. caesius samples.

In life, adult males presumed to be in breeding coloration closely resemble the holotype. Different individuals vary primarily in the amount of black on the dorsum. In some, black is restricted principally to the head and neck region. In others, it extends nearly to the rump. There is also some variation in the intensity and extent of turquoise in the head and neck area.

Some of the adult males in our sample lack the two­tone color pattern. In these individuals, the dorsum is light­brown, the head and neck are mostly immaculate, and the rest of the dorsum, including the tail, is speckled with black. There is generally a faint yellowish­white dorsolateral stripe from the loreal region to rump; this stripe is brightest above forelimbs where stripe is discontinuous and thinly edged in black. The flanks are light­brown with a slight rust tinge, immaculate, and become lighter towards venter. The chin and throat are whitish with diffuse patches of blue­black and remainder of venter immaculate yellowish­white. Adult females have very similar coloration.

In juveniles, the head and neck are bronze­brown and immaculate. Trunk dorsum gradually darkens from bronze brown on the neck to dark brown on the rump and is speckled with white. A thin whitish dorsolateral stripe extends from the eye onto neck then breaks into a series of small whitish blotches, which coalesce at the rump into a continuous row of blotches extending along the tail. A thin indistinct tan stripe lies one scale row medial to the dorsolateral stripe and extends from the parietal area to the rump. The flanks are dark brown to black with numerous scattered yellowish­white spots. The venter, including the chin and throat, are immaculate white to cream.

In preservative, the color of all life stages are muted and the overall appearance is the typical adult “fuscum” of various shades of brown dorsally and laterally, but with various degrees of darkening of the venter from chin to the chest in adults. The juvenile pattern is a brown dorsum with dark scale edges, and these edges occasionally align, forming very narrow dark brown stripes ( Fig. 2 ). A broad dark brown (black) band extends from the temporal area to inguen; it is bordered above by a dorsolateral white stripe from above eye to anterior trunk, thereafter fading and/or breaking into a series of spots or lines. The lateral band is also bordered below by a white midlateral stripe that fades or breaks into spots at midbody. Ventrally, juveniles are immaculate white or cream from chin to base of tail. Adults retain the brown dorsum of juveniles and variously alter the lateral and ventral patterns, mainly with females (except the larger ones) retaining a subdued juvenile pattern and males losing any pattern on the trunk and appearing monochrome although dorsum darker and grading into the lighter venter.

In an attempt to quantify coloration to examine the shift from juvenile to adult pattern (preserved specimens), we recognized five color traits: 1) difference in contrast between trunk dorsally and ventrally; 2) level of lateral “white” spotting on side of neck and trunk; 3) length of mid­lateral “white” stripe; 4) chin and throat color; and 5) side of neck color. We also categorized individuals in this color sample as either strongly tricarinate or weakly keeled/smooth. This color sample consised of 20 juveniles (<40 mm), 43 adult females, and 23 adult males. There was no significant difference in the proportion of strongly tricarinate adult females and males (χ 2 = 0.01, df 1, p = 0.91), approximately 22–24% of the adults in each sex were strongly keeled. In contrast, strongly tricarinate individuals represent about 60% of the juveniles. Stronger keeling in juveniles versus adults occurs regularly in other C. fusca complex species.

The color coding demonstrates the fading of coloration (pattern) from juvenile to adult. Only the lightly colored chest is persistent in the three groups (χ 2 = 4.2, df 2, p = 0.38). With the exception of a greater proportion (95%) of adult males having darker chins and throats than juveniles (40%) or adult females (72%), juveniles are more brightly or contrastingly colored in preserved specimens. Adult males and females share the same proportion (color pattern) of the other color traits.

Natural history

Carlia caesius is heliothermic. In the Timika area, it is often observed basking in patches of sunlight on the floor of primary and secondary lowland alluvial rain forest. These forests have a semi­closed canopy that is 30–35 m high and are dominated by large buttressed trees and lianas. The forest floor is relatively open with a thin layer of leaf litter or bare ground and a sparse growth of herbs and shrubs. Some of the dominant tree genera include Pometia (Sapindaceae) , Celtis (Ulmaceae) , Octomeles (Datiscaceae) , and Syzygium (Myrtaceae) .

There are at least three other similarly sized, ground­dwelling, heliothermic species of skinks inhabiting these forests, including Emoia aenea , E. jamur and E. tropidolepis . These species, together with Carlia caesius prefer relatively open parts of the forest that receive moderate to abundant sunlight. Another skink, Lygisaurus [ Carlia ] novaeguineae, a smaller species, also inhabits the forest floor but tends to prefer denser forest that the other species. Emoia caeruleocauda also occurs in these forests but tends to be semiarboreal and forage in low vegetation such as shrubs and fallen trees.

Carlia caesius also occurs in disturbed habitats such as village margins and garden clearings where in the Timika area it co­occurs with at least five species of heliothermic skinks, including Emoia aenea , E. jamur , and E. tropidolepis which occur in small numbers on the ground, and E. caeruleocauda and E. longicauda which are semi­arboreal and arboreal, respectively, and common. Carlia caesius is by far the most abundant lizard in disturbed areas.

Common trees in these areas include Macaranga sp. ( Euphorbiaceae ), Casaurina equisetifolia (Casurinaceae), Campnosperma montana (Anacardiaceae) , Pisonia sp. ( Nyctaginaceae ), Linociera sp. ( Oleaceae ), Artocarpus sp. ( Moraceae ), and Pandanus sp.

( Pandanaceae ).

The Timika area has a mean temperature of 25.9 ºC with little seasonality (monthly means range from 24.2 to 26.6 ºC). Rainfall is somewhat more seasonal, with a peak in July but no distinct dry season. Generally, monthly rainfall is at least 200 mm with an average of about 20 rain days each month.

Figures

FIGURE 2. Juveniles of Carlia caesius (BPBM 21195 [left], BPBM 21203 [right]), dorsolateral aspect, preserved.

FIGURE 5. Distribution of sample localities [left] and Carlia fusca complex species [right] in Papua­Indonesia. Sample localities: 1, Ayamaru; 2, Manokwari; 3, Fak­Fak; 4, Tanah Merak; 5, Saengga; 6, Mandiwa; 7, Yeretina; 8, Gariau; 9, Unipo; 10, Uta; 11, Freeport; 12, Lorentz River; 13, Agats; 14, Bayum.

FIGURE 1. A paratype of Carlia caesius n. sp., dorsolateral aspect, male in life, BPBM 21157.