Eremiascincus musivus, Mecke, Sven, Doughty, Paul & Donnellan, Stephen C., 2009

Mecke, Sven, Doughty, Paul & Donnellan, Stephen C., 2009, A new species of Eremiascincus (Reptilia: Squamata: Scincidae) from the Great Sandy Desert and Pilbara Coast, Western Australia and reassignment of eight species from Glaphyromorphus to Eremiascincus, Zootaxa 2246, pp. 1-20 : 10-16

Eremiascincus musivus sp. nov.

Mosaic desert skink (German—Mosaik-Wüstenskink) Figures 4 –6

Holotype. WAM R 165266 m (M). Type locality: 20 km ENE Karratha at 20°47'10"S, 116°38'29"E. Collected by Roy Teale on 31 October 2005.

Paratypes ( WAM prefixes excluded). R70927 (M)— 46.5 km WSW Gorda Tower, 18°53'30"S, 123°02'30”E; R 139046 m (M)—Mandora 19°48'30"S, 121°27'50"E; R 139083 m (F)—Mandora, 19°48'44"S, 12128'25"E; R163962 (F)— 27 km NE Warrawagine Homestead, 20°47'17"S, 120°54'04"E; R 165264 m (M) and R 165265 m (F)— 20 km ENE Karratha, 20°47'10"S, 116°38'29"E; R165833 (M)— 10 km W Port Hedland, 20°22'47"S, 11834'06"E; R 166120 m (M)—Dampier area, 20°46'49"S, 116°38'25"E; R 166117 m (M), R 166119 m (M), R 166121 m (F)—Dampier area, 20°46'48"S, 116°38'26"E.

listed in column headings, unless noted for individual characters below. Mean±SD (range). For a key to the variables see

Table.1

continued next page Diagnosis. A small, slender Eremiascincus (maximum SVL 59.2 mm), distinguished from other members of the genus by the following combination of characters: ground colour reddish to yellowish brown with a characteristic, consistent dorsal pattern of numerous whitish and dark spots often aligning to form short streaks in an irregular, diffuse reticulum; the presence of a pale vertebral stripe running from the neck to the base of tail (occasionally extending to tail); narrow, wavy, dark bands on the tail (~ 35), which are divided medially and interspaces between these dark bands, which consist of dark-edged pale scales in a single row; homogenous, smooth scales on the dorsum and tail; scales along the top of fourth toe with oblique sutures on basal quarter to third of digit, followed by single rows of scales with transverse sutures; 4TLam undivided and only feebly keeled; plantar scales 10-15; small circular ear opening; MBSR 29–34, PVS 52–62; SupraLab usually 7; 3 chin shields and 1 median chin shield.

Description. Body proportions. Head moderate, barely distinct from neck ( Figs. 4 , 6); external ear opening prominent, small and circular, about one-third size of eye; tympanum sunk, hardly visible; snout rounded in profile; body slender, with well-developed, overlapping, pentadactyl limbs; SVL 43.9–59.2 mm, 4.4–4.9 times HeadL1; TrunkL ~ 41–55% of SVL; ArmL ~ 25–31% of SVL and LegL ~ 38–45% of SVL; forelegs reaching the eye when adpressed; hindlimbs long, reaching beyond the middle of axilla-groin when adpressed, digits moderately long and slender; finger length: 4>3>2>5>1; toe length 4>3>5>2>1; claws strong with long sharp tip; tail round in cross-section with a very gradual taper to its pointed tip; unregenerated TailL 108–150% of SVL.

Scalation. Head scales smooth; rostral trilobed, wider than high, its part visible in dorsal view distinctly narrower than the frontonasal; nasals widely separated by the prefrontal, slightly longer than high and in broad contact with frontonasal scale; nostril positioned medially in nasal; frontonasal usually 1.4 times wider than long, laterally contacting anterior loreal; supranasals absent and nasals undivided; prefrontals large, pentagonal and separated by a medial scale; frontal shield elongate, nearly two times as long as wide, much longer and narrower than prefrontal region, in contact with frontonasal shield; supraoculars 4, first 2 on each side contacting frontal, first one usually in contact with 3 SupCil; frontoparietals paired, in contact with second, third and fourth supraoculars; interparietal 1.3–1.6 times longer than wide; about half the size of frontal, as long as frontoparietals, with light pineal organ visible in posterior lobe; parietals meeting behind interparietal, each in contact with fourth supraocular, frontoparietal, interparietal, upper secondary temporal and 1 or 2 pretemporal scales; nuchals 0–2 on each side; loreals 2; anterior loreal twice as high as long, touching frontal and prefrontal; posterior loreal larger, slightly higher than long; preoculars 2, upper smallest; SupCil 7–10 (usually 8), in a continuous row, first largest, contacting prefrontal and first supraocular; last large and projecting medially between last supraocular and first pretemporal; presuboculars 2, second higher than long; postsuboculars usually 3; pretemporals 2, upper larger, lower vertical and about three times as high as long; lower eyelid movable and scaly; temporals 3, primary temporal 1, quadrangular and oblique; secondary temporals 2, upper secondary much longer than wide and broadly in contact with parietal, lower secondary larger than last labial shield, overlapped by posterior margin of primary temporal and in contact with vertically arranged, narrow scales posteriorly; SupraLab 6 or 7 (usually 7), fourth or fifth (usually fifths) in subocular position, slightly higher than long, last two largest, usually smaller than lower secondary temporal, last SupraLab separated from ear by 4 or 5 scales occupying a space equalling its length; postsupralabials 2; InfraLab 5–7, usually only the first infralabial in contact with postmental scale; mental shield large, wider than rostral, followed by postmental and 3 pairs of enlarged chin shields; first scale in contact, second scale separated by a single median chin shield; anterior margin of ear aperture with small granules or rudimentary lobules (4 or 5).

Body scales imbricate, 4-sided, regular and arranged in parallel longitudinal rows; dorsal scales homogeneous, smooth, polished; scales in median dorsal rows as wide as long; lateral scales smallest; 29–34 MBSR; PVS 52–62, not enlarged; limbs with smooth cycloid scales in parallel longitudinal rows; subdigital lamellae of fourth toe 18–26, feebly keeled, undivided (except basal 1–4); multiple rows of scales with oblique sutures covering the top on at least basal quarter of fourth toe, followed by scales with transverse sutures in single rows ( Fig. 4 ); relatively small plantar scales, rounded in dorsal view, slightly raised and pointed in profile (12.9±1.2, counted in a line drawn between the basal lamella of third toe and lower imbricate scales of hindlimb, N = 25); caudal scales larger than dorsals, two times wider than long, without ridges; a median ventral series of enlarged subcaudal scales; 4 enlarged preanal scales, median preanal scales largest, overlapping outer; 3 or 4 postanal transverse rows of smaller scales.

Colouration ( Figs. 5 , 6). In life, dorsum light yellowish or orange brown, with whitish and dark brown spots aggregated to form a diffuse reticulum; a pale vertebral stripe runs from the back of head to the base of tail; sides generally spotted with larger pale dashes; limbs yellowish or greyish brown without any pattern; tail with dark, narrow bands, which are divided medially; interspaces between bands consist of one row of darkedged scales; some head scales with dark spots or lines, e.g. margins of supraoculars and parietals; occasionally with a dark line at the anterior border of the eye opening in subocular position; labial shields whitish, sutures edged light greyish-brown; venter, including chin and throat uniform whitish-grey to cream; plantar scales and digital lamellae slightly darker pigmented.

In preserved specimens, the colour and pattern of the dorsum and the tail is subdued; the ground colour varies from light yellowish brown to dark greyish brown; nonetheless, the typical mosaic-like dorsal colour pattern and the dark bands covering the tail remain evident; a pale vertebral stripe was evident in 89% of specimens examined (N = 27); the head scales usually show dark markings and the labial shields are edged with darker colour. The colour of the venter becomes yellowish-white.

Variation. Juveniles show the same, characteristic colour pattern. Colour variation shows some local minor individual variation, but relatively little geographic variation. Some specimens collected near Mandora (e.g. WAM R139042, R139046, R139083, R162974) differ in the intensity of dark brown or black spots and some lack darker pigments on the dorsum. In other respects (e.g. caudal colour pattern, squamation of the digits) these specimens are typical of E. musivus .

Details of holotype. ( WAM R156266): SVL — 59.2 mm; TrunkL — 31.2 mm; TailL — 79 mm; ArmL — 15.9 mm; LegL — 22.2 mm; AxillaEar — 10.8 mm; HeadL 1 — 11.8 mm; HeadL 2 — 11 mm; HeadW — 7.5 mm; HeadH — 5.2 mm; SnoutL — 4.9 mm; FootL — 9 mm; Toe3L — 4.5 mm; Toe4L — 6.1 mm; EarL — 0.9 mm; EarH — 1.1 mm; MBSR — 29; PVS — 52; SupLab — 7; InfraLab — 6; 4TLam — 21; SupCil — 9; Nuchals — 1; Prefrontals separated.

Distribution. This species has been found in desert habitats, buffel- and spinifex grassland and low shrub land of the Pilbara Coast, Dampierland and the Great Sandy Desert of Western Australia, where it is sympatric with E. fasciolatus , E. richardsonii and E. isolepis ( Fig. 3 ). The area of distribution extends from the Dampier area (21°S; 116°E) along the coast to Mandora (ca. 19–20°S; 121°E). Although most specimens of E. musivus have been collected in coastal areas of the Pilbara region and Dampierland, the species’ distribution extends to the northern parts of the Great Sandy Desert (19°S; 123°E) with the easternmost record from the St. George Ranges (18°S; 125°E). The new species likely ranges over much of the northern Great Sandy Desert. However, the coastal area of distribution of E. musivus appears to be unique among lizards reported from that area.

Habitat preferences, reproduction and behaviour. The new species is abundant in microhabitats with both loose and hard soil with dense to scattered spinifex ( Triodia ) and buffel grass (Chenchrus) cover and low shrubs ( Fig. 7 ). Some specimens were collected on dunes and sandridges with orange to red siliceous sand. Individuals of E. musivus have also been observed in low woodlands of Eucalyptus , Grevillea and Acacia . Some morphological characters, however, such as a small circular ear opening, indicate that the species presumably is fossorial (see also Greer 2002). Examination of gut contents indicated that individuals feed on invertebrates and small lizards. Cannibalism also occurs, as a preserved specimen had a smaller conspecific in its gut.

Eremiascincus musivus matures at a SVL of approximately 49 mm. Females are oviparous and vitellogenesis begins in spring, between September and October, based on the presence of enlarged follicles during this period. The appearance of enlarged testes in males coincides with the appearance of follicles in females. Oviposition presumably takes place until late summer. One female collected in mid-February contained three shelled oviducal eggs that were ~ 6 mm in diameter. The timing of reproduction in E. musivus appears to be similar to that recorded for other congeners inhabiting the Australian arid zones ( James et al. 1991). Like its congeners, the new species is most likely crepuscular or nocturnal, and one specimen was collected at night on a road. However, little is known about the ecology of the species at present.

Comparisons with other Western Australian species. Eremiascincus musivus is distinguished from the sympatric congeners E. isolepis and the allopatric E. brongersmai by scales along the top of the fourth toe in multiple rows with oblique sutures along basal quarter or third of digit, followed by more than five single scales with transverse sutures (only distal 1–3 scales in E. isolepis and E. brongersmai have transverse sutures), 4TLam undivided along almost entire digit and only feebly keeled, while at least divided along basal quarter of digit and strongly keeled or callused in both other taxa, a slightly depressed snout and a small circular ear opening. The new species also differs from the larger, sympatric E. richardsonii in having undivided subdigital lamellae and a small circular ear opening. In addition, E. richardsonii has a dorsal pattern consisting of sharply defined, dark brown bands across the body instead of numerous pale and dark spots, divided, dark callused subdigital lamellae, a large subcircular or elliptical ear aperture and is furthermore characterised in usually having four chin- and two median chin shields (96% of E. richardsonii examined for this study had four chin shields on both sides of the head and 80% had two median chin shields; N = 25). E. isolepis usually has a heavily speckled dark brown lateral zone and speckled hindlimbs, both of which are absent in E. musivus . The larger E. brongersmai has a sharply defined solid dark dorsolateral streak at the anterior part of the body, dark spots on the limbs, which align longitudinally and 6 SupraLab instead of 7. Both E. isolepis and E. brongersmai also share a colour pattern in which dark banding on the tail is absent. The new species differs from the sympatric E. fasciolatus by fewer PVS (52–62 versus 59–69), a lower number of plantar scales (12.9±1.2, range 10–15 in E. musivus , N = 25 versus16.0±0.9, range 14–18 in E. fasciolatus , N = 20); smooth supracaudal scales instead of keeled scales, scales along the top of the fourth toe in multiple rows with oblique sutures along basal quarter or third of digit (instead of single rows with transverse sutures along almost entire digit) and smaller body size. Eremiascincus musivus shows some morphological similarities with E. fasciolatus . The two species are desert inhabiting and show similar morphological and ecological characteristics. The fingers and toes of both taxa are covered with a higher number of single rows of scales than in the more mesic taxa and the lamellae are undivided and only feebly keeled, which may reduces contact with the sandy ground. The snout is somewhat depressed and the ear opening is small and almost circular. However, E. fasciolatus lacks an obvious dorsal colouration of dark and pale blotches and a pale vertebral stripe. In addition, the dark bands on the tail are more sharply defined and perfectly transverse in E. fasciolatus , while medially divided and more diffuse in E. musivus . In E. musivus , the sides are spotted with white dashes and the sutures between the supralabials are edged with light greyish or reddish-brown, in contrast to E. fasciolatus . The new species has a smaller mean adult SVL than E. fasciolatus and E. isolepis , both in males and females and a relatively longer tail than E. fasciolatus ( Table 2 ).

Etymology. The specific epithet (from Latin, meaning ‘tessellated’) refers to the unique dorsal colour pattern formed by numerous whitish and dark spots. Used as a noun in apposition.

Figures

FIGURE 3. Map showing the distribution of E. fasciolatus (open triangles), E. isolepis (shaded circles), and E. musivus sp. nov. (solid squares) based on vouchered museum specimens.

FIGURE 4. Drawings of head and dorsal scalation of the digits of the pes (left side) of holotype of Eremiascincus musivus

FIGURE 5. Dorsum (A) and flank (B) of preserved holotype of Eremiascincus musivus sp. nov., (WAM R 165266). Total length = 138.2 mm. Photograph—R. Heitzmann.

FIGURE 7. Habitat of E. musivus sp. nov. 20 km ENE Karratha, Pilbara coast, northern Western Australia. Sloping dune with buffel grass vegetation on red siliceous sand. Both the holotype (WAM R 165266) and two paratypes (WAM R 165264 – 5) were collected from this site. Photograph—Biota Environmental Sciences Pty Ltd.

Tables

TABLE 2. Summary of characters and ratios measured for Eremiascincus from Western Australia. Sample sizes are

Character	E. musivus sp. nov. N = 27	E. fasciolatus N = 35	E. isolepis “Pilbara ” N = 25	E. isolepis “Kimberley ” N = 31
SVL	Females (N = 10): 52.6±3.1 (48.3–56.9) Males (N = 17): 51.3±4.6 (43.9–59.2)	Females (N = 15): 65.6±5.8 (57.5–75.6) Males (N =20): 67.7±4.3 (58.5–73.9)	Females (N = 11): 57.3±2.9 (52.9–61.6) Males (N = 14): 59.5±3.8 (50.0–64.1)	Females (N = 12): 58.7±4.0 (52.5–64.4) Males (N = 19): 59.1±5.0 (49.6–67.4)
TrunkL	Females (N = 10): 27.7±2.7 (24.9–32.8) Males (N = 17): 26.0±3.4 (19.1–31.2)	Females (N = 15) 35.9±3.3 (31.4–42.8) Males (N=20) 36.2±3.4 (28.8–43.9)	Females (N = 11) 32.6±3.2 (28.6–39.8) Males (N = 14) 33.4± 2.9 (28.4–38.0)	Females (N = 12) 33.0±3.0 (28.1–37.5) Males (N = 19) 32.4±3.3 (27.5–37.5)
TailL	69.6±5.2 (58.7–79.0) N = 11	76.8±5.2 (69.0–86.0) N = 10	97.7±7.0 (86.2–107.0) N = 7	92.1±6.6 (86.0–105.7) N = 8
ArmL	14.9±0.8 (13.5–16.3)	18.4±1.2 (15.9–20.0)	13.7±0.6 (12.6–14.6)	12.5±0,7 (11.1–14.0)
LegL	21.1± 1.0 (19.1–23.1)	25.8±1.7 (22.5–29.2)	19.9±0.8 (18.2–21.1)	19.0±1.1 (16.6–21.5)
AxillaEar	9.9±1.1 (7.7–12.4)	12.3±1.2 (10.5–14.8)	10.3±0.9 (8.3–12.0)	10.9±1.1 (16.6–21.5)
HeadL 1	11.0±0.6 (10.0–12.0)	12.9±0.9 (10.9–14.3)	10.8±0.6 (9.8–11.9)	10.7±0.7 (9.5–12.2)
HeadL 2	10.3±0.6 (9.1–11.3)	12.0±0.9 (10.3–13.5)	10.1±0.4 (9.4–10.9)	10.1±0.6 (9.1–11.6)
HeadW	6.9±0.6 (5.6–8.1)	8.0±0.7 (6.4–9.2)	7.0±0.5 (6.3–8.1) N = 24	7.2±0.7 (5.8–8.7)
HeadD	4.9±0.4 (4.3–5.7)	5.6±0.5 (4.7–6.4)	4.8±4.0 (4.1–5.9)	4.8±0.5 (4.1–6.2)
SnoutL	4.6 ±0.4 (3.9–5.5)	5.6±0.5 (4.8–6.5)	4.4±0.3 (3.8–5.0)	4.4±0.4 (3.7–5.2)
FootL	9.0 ±0.6 (7.8–10.2)	11.0±0.8 (9.2–12.6)	8.5±0.5 (7.3–9.4)	8.0±0.4 (7.1–8.7)
Toe3L	4.6±0.4 (3.8–5.5)	5.5±0.4 (5.0–6.4)	4.3±0.2 (3.8–4.6)	4.0±0.3 (3.3–4.7)
Toe4L	6.3±0.4 (5.6–7.1)	7.8±0.5 (6.7–8.9)	5.9±0.2 (5.5–6.4)	5.6±0.3 (4.8–6.1)
EarL	0.8±0.1 (0.6–1.1) N = 26	0.9±0.2 (0.6–1.3) N = 32	1.1±0.2 (0.9–1.9)	1.0±0.2 (0.6–1.7)
EarH	0.8±0.2 (0.6–1.2) N = 26	0.9±0.2 (0,6–1.3) N=32	1.2±0.2 (0.9–1.9)	1.1±0.2 (0.7–1.5)
EarArea	0.5±0.1 (0.3–0.8) N = 26	0.7±0.2 (0.3–1.3) N = 32	1.0±0.4 (0.6–2.8)	0.8±0.3 (0.4–1.9)
MBSR	30.5±1.2 (29–34) N = 26	32.4±1.1 (30–35)	29.7±1.0 (28–32)	27.5±1.4 (25–30)
PVS	56.3±2.4 (52–62)	65.1±2.8 (59–69)	62.0±2.0 (59–66)	58.0±2.9 (54–67)
SupraLab	7.0±0.2 (6–7)	7.0±0.3 (6–8)	7.0±0.0 (7)	7.0±0.0 (7)