Stephens' Banded Snake

Stephens's banded snake (Hoplocephalus stephensii) is a species of highly venomous tree snake in the family Elapidae. The species is endemic to Australia.

Taxonomy

Gerard Krefft described Hoplocephalus stephensii as a species new to science in 1869. The specific name stephensii, is in honour of Australian academic William John Stephens.

Description

H. stephensii grows up to 1 meter (39 inches) in total length (including tail), with some specimens having been recorded as having a total length upwards of 120 cm (47 in). The Stephens' banded snake is the largest species within the genus Hoplocephalus, weighing up to 250 g (8.8 oz) as an adult. On average, females of this species are larger than males. This slight sexual dimorphism is an adaptation that likely improves the reproductive capabilities of females.

The anterior scalation of Stephens's banded snake consists of 21 rows of midbody dorsal scales, and 220 to 250 ventral scales. Posteriorly, its singular subcaudal scales can range between 50 and 70 scales from the anal plate to the tip of the tail. This species has a singular (undivided) anal plate that covers its cloacal opening. The ventral scales of the genus Hoplocephalus differ from other elapids as they have lateral notches along the caudal border of each of these scales. This adaptation aids with gripping onto branches whilst climbing. Additionally, the occipital scales on the head of this snake are elongated.

The body of the Stephens's banded snake is adorned with alternating grey or black and dirty-white bands of colouration on the dorsal side of the snake. These snakes may have over 40 of each colour band from the back of the head to the tip of the tail. Whilst the flat and quadrangular belly of the snake is mostly dirty-white with occasional splotches of grey towards the head and tail end of the snake. The top of this species' head is typically dark brown in colouration, and it has pale blotches or bars of patterning along the lips.

The morphological composition of a slender body and broadened arrow-shaped head also allows for more agile locomotion in an arboreal habitat whilst also having the capability of predating on a large range of species within the ecosystem. This unique body plan essentially reduces metabolic costs, allowing the snake to retain energy for longer periods of time.

Distribution and habitat

The Stephens's banded snake is endemic to the east coast of Australia. The distribution of this snake spans from its northern most range in the Kroombit tops of south-eastern Queensland down to the Gosford Area of New South Wales. Within this coastal range, the species is typically restricted to high-rainfall remnant forest regions, secluded from human intervention. The Stephens's banded snake can be found up to an altitude of 950 m (3,120 ft) above sea level within its geographical range. Studies on the habitat preferences of this species have found that it prefers to reside around 20 m (66 ft) high in canopy trees.