Varanus hamersleyensis, Maryan, Brad, Oliver, Paul M., Fitch, Alison J. & O’Connell, Morgan, 2014

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 : 150-155

Varanus hamersleyensis sp. nov.

Southern Pilbara Rock Goanna ( Figs. 8 , 9 , 10 )

Material examined. Holotype: WAM R145733, male, Hamersley Range, Weeli Wolli Creek (22º52'40"S 119º14'24"E), Western Australia, Australia, R. Teale & G. Harold, 28 April 2003. Fixed in 10% formalin, stored in 70% ethanol, liver sample stored in –80ºC ultrafreezer at WAM. Paratypes: All from Western Australia. WAM R125456 (male)— 30 km E Newman (23º19'S 120º02'E); WAM R125766 (female)—Circular Pool, Dales Gorge (22º38'36"S 118º33'47"E); WAM R129628 (male)— 120 km NW Newman (22º55'S 119º01'E); WAM R 140734 (female)—Rocklea Station (22º56'55"S 117º16'0 7"E); WAM R164579 (male)— 8.5 km NE Mount Rica (21º57'0 8"S 116º29'18"E).

Diagnosis and comparison. Differs from all Australian congeners by the following combination of characters: size moderately small (SVL up to 160 mm); slender build; tail long (between 168–207% of SVL) and thin, circular in cross section at midpoint, midbody scales 120–122; dorsal and lateral 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 subdued irregular dark brown to black spots or vermiculations on a dark reddish-brown background, small ocelli on the dorsal surface of the hindlimbs only, and tail without prominent dark bands.

Varanus hamersleyensis sp. nov. differs from its sister species V. pilbarensis in its overall darker colouration, presence of small whitish ocelli usually on the dorsal surface of the limbs only ( v. large greyish ocelli on the dorsal and lateral surfaces of body and limbs), largely unbanded tail ( v. strongly banded tail) and smaller and less elongate dorsal scales ( Fig. 3 B).

Description of holotype ( Fig. 8 ). Small-bodied Varanus with 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, wider than high, 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 and unornamented; supraocular scales smaller than those on the rostrum, frontal and parietal regions; canthus rostralis weak; rostral scale twice as large as adjacent scales, almost rounded, slightly narrower anteriorly; mental scale higher than wide and almost rectangular.

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 darkly pigmented, relatively short, very thick, laterally compressed and with sharp, recurved tips.

Dorsal primary scales small, non-overlapping, relatively uniform and ovate, approximately twice as long as wide and with a small central keel; bordered by row of small granules; ventral scales non-overlapping and more rectangular, approximately 50% longer and 100% wider than dorsal scales, grading smaller on the throat and vent; 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 lateroventral rows of long, narrow pointed scales, increasing in height, size and spinosity distally.

In preservative, ground colour of dorsum dark brown, slightly lighter on head and neck. Patterning on head includes black spots on some individual scales and dark brown labial bars, dorsal surfaces of torso with mixture of irregular black spots on individual scales or spots coalesce to form narrow, wavy transverse lines. Light brown tail with irregular dark brown to black spots. Forelimbs light brown, hindlimbs darker brown with small whitish ocelli becoming more prominent distally. Ventral surfaces greyish.

Variation. Summary mensural and meristic data for the type series of V. hamersleyensis sp. nov. is presented in Tables 1 and 3 . In preservative, the ground colouration is always brown ( Fig. 10 ). All specimens have irregular dark spots on some individual scales or vermiculations across the dorsum, although these vary in degree and intensity; on one individual (WAM R125766) the entire dorsum has very fine spots with barely any indication of alignment, while at the other extreme (WAM R 140734) the dense spots align to form regular wavy lines. Most individuals have some dark spotting on the tail, although one individual (WAM R164579) has almost none. The venter sometimes features relatively bold greyish bands that become more narrow and wavy on neck and throat.

Two juvenile specimens (WAM R69695: SVL 61.6 mm; WAM R125100: 70 mm) are more brightly patterned than adults with much larger spots on dorsum, more contrasting and strongly defined ventral surface bands and obviously ringed tails.

Colouration in life. The following description of colouration in life is based on Figs. 9 A, B and a photograph from Mount Channar near Paraburdoo ( Ehmann 1992). Dorsal ground colour of head, torso and limbs dark reddishbrown, often tending slightly paler on head. Head and neck with irregular subdued small blackish-brown to black spots, snout forward of nostrils often dark brown, sides of head with yellowish tinge. Labial scales with blackishbrown vertical bars. Dorsal surface of torso with numerous small blackish-brown to black spots, often coalescing into narrow (one scale wide) transverse bars or wavy lines and forming a fine black reticulum. Forelimbs reddish brown with dark flecks, hindlimbs noticeably darker brown with small whitish ocelli. Digits on both limbs with indistinct thin pale yellowish bands. Ground colour of the tail light brown, extensively overlain with darker-brown to black spots along its length. Ventral surface of the throat, neck, limbs and body greyish-white.

Habitat and ecology. Varanus hamersleyensis sp. nov. is strictly saxicolous and closely associated with rocky habitats such as banded ironstone rock faces and gorges ( Fig. 11 ). It shelters in overhangs, crevices, cavities and occasionally under exfoliated rock slabs. Typical vegetation on these faces varies, but often includes Eucalyptus and Triodia (Spinifex) . Field observations indicate a preference for flat, horizontal sheet ironstone with an eastwest aspect to allow optimum basking in the morning. It is extremely swift and agile; ascending vertical rock faces with ease, and quickly takes shelter in deep crevices when disturbed.

As with V. pilbarensis ( Ehmann 1992; B. Maryan pers. obs.), this species has been observed active after sunset on warm, humid nights. Field observations indicated that activity periods vary seasonally, peaking during the hotter and humid months from October–April and declining when conditions are dry from May–September. The sex ratio among the type series of V. hamersleyensis sp. nov., including the misidentified paratype of V. pilbarensis (WAM R14901) is skewed (5 adult males and 2 adult females), a bias which seems to be consistent with museum series of other opportunistically collected varanids ( Greer 1989) and may reflect different activity periods of the sexes. During surveys in the eastern Hamersley Range, most individuals captured were also males (B. Maryan and M. O’Connell, unpublished data).

Distribution. Known only from the Hamersley Range, a heavily dissected region of banded ironstone occupying the southern part of the Pilbara craton of Western Australia. Records span the Hamersley Range for over 300 km from east of Newman (WAM R125100, WAM R125456) west to Mount Rica (WAM R164579) and south to Rocklea Station (WAM R 140734) (Fig. 2).

Etymology. Named for the Hamersley Range of Western Australia, the region to which it is restricted. This is the most prominent mountainous area in Western Australia (including Mount Meharry, 1245 m, and the highest peak in the state) and home to a suite of endemic taxa. Used as a noun in apposition.

Remarks. This species appears to be secure and widespread throughout the Hamersley Range, and occurs in popular tourist destinations such as at Karijini National Park (one of the largest National Parks in Western Australia).

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 8. Preserved holotype WAM R 145733 of V. hamersleyensis sp. nov. in dorsal, ventral and lateral views.

FIGURE 9. Adult V. hamersleyensis sp. nov. photographed in life from (A) Marillana and (B) Ophthalmia Range (images—B. Maryan).

FIGURE 10. Variation in V. hamersleyensis sp. nov. from left to right, WAM R 125456, WAM R 125766, WAM R 140734, WAM R 164579.

FIGURE 11. Typical habitat of V. hamersleyensis sp. nov. in the Hamersley Range: a banded ironstone rock face with horizontal crevices, Mount Robinson. Note the individual in the centre, indicated by arrow (image—B. Maryan).

Tables

TABLE 3. Individual measurements (mm) and meristic counts for the type series of V. hamersleyensis sp. nov.. NA = not available.

WAM #	Sex	SVL	TL	HNL	FLL	HLL	HD	HW	BL MSR	VS	PSL
R125456	male	122.3	NA	46.7	36.4	45.5	7.5	15	75.6 120	70	22
R125766	female	121.2	217	48.7	39.4	49	6	13.2	72.5 120	66	22
R129628	male	160	270	64	44.4	64	9.4	19.8	95.9 122	70	21
R140734	female	120	NA	47.3	33.7	39.4	6.5	13.4	72.9 122	72	21
R145733	male	155.8	295	64.5	43.7	58.4	9.7	17.7	91.3 122	74	23
R164579	male	124.8	226	48.9	39.5	50.5	7.9	13.4	75.8 120	65	22