Varanus pilbarensis Storr, 1980

Maryan, Brad, Oliver, Paul M., Fitch, Alison J. & O’Connell, Morgan, 2014, Molecular and morphological assessment of Varanus pilbarensis (Squamata: Varanidae), with a description of a new species from the southern Pilbara, Western Australia, Zootaxa 3768 (2), pp. 139-158 : 145-149

Varanus pilbarensis Storr, 1980

Northern Pilbara Rock Goanna ( Figs. 4 , 5 , 6 )

Material examined. Holotype: WAM R39782, male, Chichester Range, Cockeraga River (22º03'S 118º48'E), Western Australia, Australia, J.C. Wombey, 7 April 1971. Paratypes: All from Western Australia. WAM R10811 (male)—Abydos (21º25'S 118º55'E); WAM R13082* (unsexed)—Woodstock Station (21º37'S 118º57'E); WAM R14901 ** (male)—Dales Gorge, Hamersley Range (22º30'S 118º36'E); WAM R20017 (male)—Black Hill Pool (21º19'S 117º15'E); WAM R28011–12 (males)—Woodstock Station (21º37'S 118º57'E); WAM R39158 (male)— 2 km W Nullagine (21º54'S 120º05'E); WAM R60432 (female)—Woodstock Station (21º37'S 118º57'E).

*Poor specimen not included in morphological examination.

** Represents new taxon described below.

Extended diagnosis and comparison. Differs from all Australian congeners by the following combination of characters: size moderately small (SVL up to 180 mm); slender build; tail long (between 170–211% of SVL) and thin, circular in cross section at midpoint, midbody scales 118–128; dorsal and lateral primary scales weakly keeled, enlarged keeled ventrolateral scales on each side of and posterior to vent in 4–6 rows, scales on top of head smooth; supraoculars gradually merging with larger interoculars; dorsal scales elongate, ovate; nostrils high and oriented dorsolaterally, dorsal and lateral surfaces of body with distinct transverse series of large ocelli on a light reddish-brown background, and tail with prominent alternating light and dark bands.

Varanus pilbarensis differs from its sister species in the Hamersley Range (described below) in its overall paler colouration, large greyish ocelli on the dorsal and lateral surfaces of body and limbs ( v. small whitish ocelli on limbs only), strongly banded tail ( v. completely or mostly unbanded) and larger and more elongate dorsal scales ( Fig. 3 A).

Re-description of holotype ( Fig. 4 ). Small-bodied Varanus with a depressed body. Head elongate and depressed in lateral view; upper rostrum slightly protruding over lower jaw, genial groove distinct. Tail long and gradually tapering, moderately dorsoventrally depressed proximally, circular centrally, becoming more triangular distally. Eyes large with scaly upper and lower eyelids, closer to nostril than to ear opening; supraocular brow present above eyes. Snout moderately long, rounded in dorsal and lateral views; nostrils large and visible from above, oriented dorsolaterally, approximately equidistant between tip of snout and anterior edge of eye. Ear openings much higher than wide, oriented distally at 45º to the corner of jaw. Head scales small, smooth, supraoculars gradually merging with the larger interoculars; canthus rostralis weak (not entirely absent as stated by Storr 1980), demarcated by low ridge of larger scales anterior to eye and contacting nostril; rostral and mental scales higher than wide, twice the size of adjacent scales.

Limbs well-developed and moderately slender, ventral surface of digits with enlarged paired circular lamellae, scales on manus and pes otherwise consisting of conical tubercles; claws short and thick, with strongly recurved tips. Dorsal primary scales small, relatively uniform and ovate with small central keel, bordered by row of small granules; ventral scales larger and much longer than wide; caudal scales undifferentiated on dorsal and ventral surfaces, at base of tail similar in size to dorsal scales on torso, grading to larger with moderate keels in central section of tail and narrow with sharp keels towards tip; cloacal region with paired set of 4–6 curved ventrolateral rows of long, narrow pointed scales, increasing in height, size and spinosity distally.

In preservative, ground colour light brown, with reddish tinge on head and limbs, and tending greyer on flanks. Patterning on head includes light brown spotting and similarly coloured bars on labials. Dorsal surfaces and base of tail with dark brown spots (prominent on tail) coalescing to form narrow, wavy transverse lines. Limbs with light grey ocelli, larger and more prominent on hindlimbs. Dark brown transverse bands present from mid to distal point of tail. Ventral surface white with faint light grey bands.

Variation. Tables 1–2 summarises the mensural and meristic data for V. pilbarensis . In preservative, dorsal patterning in most individuals is similar ( Fig. 6 ), consisting of fine dark brown spots on a lighter brown background. In some individuals (WAM R 100766, WAM R165513) the entire dorsum has widely scattered spots on individual scales, while in others (WAM R 102103, WAM R163916, WAM R 170132) the spots coalesce to form irregular transverse lines. The smallest individual (WAM R132659) is very boldly marked with dorsal spots almost forming wavy bars across dorsum. One individual (WAM R 110941) has a uniform dark brown body and lighter head with very indistinct ocelli on the dorsum and a strongly banded tail. All specimens have strongly banded tails. The large, pale grey ocelli are faint on some individuals (WAM R 100766).

V. pilbarensis V. hamersleyensis sp. nov.

Colouration in life. The following description of colouration in life is based on Figs. 5 A, B and field observations of V. pilbarensis from the Chichester and surrounding northern ranges. Dorsal ground colour of head, body and limbs light reddish-brown, slightly paler (tending towards yellowish) on head. Dorsal surfaces of head and neck distinctly spotted or flecked with dark reddish-brown, sometimes coalescing to form narrow wavy, transverse bands. Distinct reddish-brown to black vertical bars on labial and temporal regions. Upper surface of dorsum and base of tail with numerous small blackish-brown to black spots that coalesce into narrow (one scale wide) transverse bars or wavy lines. Between these spots are transverse rows of large greyish ocelli. These ocelli vary in degrees of intensity and with body size but are clearly discernible posteriorly at any stage of maturity. Limbs dorsally and laterally with irregular pale grey or whitish ocelli (often dark-edged and/or dark-centred) and, larger and brighter on hindlimbs. Ground colour of proximal section of tail light brown or greyish, often with large greyish ocelli; ground colour of distal section of tail grading from cream to white with dark reddish-brown to black rings, giving a distinct banded appearance. Ventral surfaces of throat, neck, limbs and body greyish-white, often with irregular transverse grey bands or reticulations.

Juveniles are more simply and very brightly patterned, with large black-edged pale ocelli on dorsum and limbs, distinct reddish-brown heads and black and white banded tails.

Habitat. This species is closely associated with rocky habitats ( Fig. 7 ), typically undulating granite and greenstone terrain with significant areas of basaltic ranges (tumbled boulder piles are prominent) and dissected plateau, vegetated with Triodia , sparse shrubs and eucalypts (Mckenzie et al. 2009).

Distribution. Endemic to the northern Pilbara region of Western Australia, largely to the north of the Fortescue River Basin and centred on the Chichester Range. Records extend from the Burrup Peninsula and West Intercourse Island in the northwest, east to the Ord Ranges, Yarrie Mine and Carawine Gorge. There is a single record south of the Fortescue River in the western Chichester Range near Pannawonica (Fig. 2).

Etymology. Named for the Pilbara region of Western Australia, the region to which it is restricted. Used as a noun in apposition.

Remarks. This species appears to be secure and widespread throughout the Chichester Range and other northern ranges, and occurs in popular tourist destinations such as at Millstream Chichester National Park. This species can be locally abundant in suitable rocky areas. Varanus pilbarensis is illustrated in numerous publications (e.g. Storr et al. 1983: Plate 15; Vincent & Wilson 1999: 75; Pianka et al. 2004: 430; Eidenmüller 2007: 105; Wilson & Swan 2013: 429).

Figures

FIGURE 3. Details of primary dorsal scales and granules in (A) WAM R 102103, V. pilbarensis and (B) WAM R 129628, V. hamersleyensis sp. nov .. Scale bar 1 cm.

FIGURE 4. Preserved holotype WAM R 39782 of V. pilbarensis in dorsal, ventral and lateral views.

FIGURE 5. Adult V. pilbarensis photographed in life from (A) Ord Ranges and (B) 55 km ENE Pannawonica, (images—J. Vo s).

FIGURE 6. Variation in V. pilbarensis from left to right, WAM R 100766, WAM R 102103, WAM R 163916, WAM R 170132.

FIGURE 7. Typical habitat of V. pilbarensis in the northern Pilbara: granite outcrop with numerous crevices and exfoliations, Karratha Station near Karratha. Note the basking individual in the foreground, indicated by arrow (image—B. Maryan).