Stripetailed monitor

Varanus caudolineatus

SUBFAMILY

Varanines

TAXONOMY

Varanus caudolineatus Boulenger, 1885, Champion Bay, Western Australia.

OTHER COMMON NAMES English: Line-tailed pygmy monitor.

PHYSICAL CHARACTERISTICS

Both sexes appear to mature at about 3.6 in (91 mm) SVL, the size of the smallest male with enlarged testes and the smallest gravid female. One specimen with an SVL of 4.4 in (111 mm), estimated to weigh 0.53 oz (15 g), contained an intact 0.1-oz (3-ml) Gehyra (20% of its mass).

DISTRIBUTION

Central and interior Western Australia.

HABITAT

The stripe-tailed monitor is semiarboreal, preferring habitats with mulga trees, which offer small hollows that provide the lizards with tight-fitting safe diurnal and nocturnal retreats.

BEHAVIOR

Movements of stripe-tailed monitors marked with a radioactive tracer were not nearly as extensive as movements observed in other species of varanids, suggesting that these pygmy monitors may be fairly sedentary.

FEEDING ECOLOGY AND DIET

These monitors descend to the ground to forage, evidenced by the fact that three of the 13 active specimens observed were on the ground when first sighted. Moreover, one stomach contained a ground-dwelling Rhynchoedura ornata gecko. Others contained tails and intact Gehyra, arboreal geckos. Gut contents of another sample consisted largely of scorpions and ground-dwelling spiders. These monitors forage on the ground searching for prey by going down into their burrows. V. caudo-lineatus (and V. gilleni) actually "harvest" the exceedingly fragile tails of geckos that are too large to subdue intact.

REPRODUCTIVE BIOLOGY

The male combat ritual for the stripe-tailed monitor is similar to that of V. gilleni and most other pygmy varanids in the Oda-tria group. It involves wrestling, longitudinal rolls while embraced with ventral surfaces adjacent, lateral twisting and flexing, and occasional biting on the flank, limbs, and tail. While embraced with both fore and hind limbs, two adversaries form an arch from their snout to their tail.

Mating behavior is similar to that in other varanids. A male will nudge and tongue-flick a female, particularly around the head and neck. Mating occurs when a male lies along the top of a female, using a hind limb and tail to expose her cloaca, enabling him to insert a hemipene. Male testes were largest during July and August, and a female with enlarged oviducts was collected in late December. Smith (1988) reports that a 1.3 oz (37 g) female V. caudolineatus laid four eggs (total mass of 0.3 oz or 9 g) on October 23, 1986. V. caudolineatus appear to oviposit over an extended period. Clutch size is usually three to four eggs.

CONSERVATION STATUS

Not threatened.

SIGNIFICANCE TO HUMANS None known. ♦

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