About Vermicella annulata (Gray, 1841)
Vermicella annulata, commonly known as the bandy-bandy, is a smooth-scaled, glossy snake with a distinctive pattern of sharply contrasting black and white rings that continue all the way around its body. This unique banding pattern clearly distinguishes bandy-bandys from other Australian land snakes; the pattern gives the species both its common name and its scientific name, which comes from annul-, the diminutive form of the Latin word anus meaning "ring".
The bandy-bandy has a relatively short tail with fewer than 35 subcaudals and a blunt tip, a feature that sets it apart from other elapids. Its dorsal scales are arranged in 15 rows at midbody. The average total length, including the tail, is 50 to 60 cm (20 to 24 in), but size varies greatly between sexes.
Bandy-bandys occupy a wide variety of habitats, ranging from desert regions to wet rainforest. For V. annulata specifically, its distribution spans across the east coast of Australia, while other Vermicella species are found in far northern Australia and the arid regions of western and central Australia. V. annulata occurs mainly in suburbs with woodland habitats, such as Mt Cotton, Mt Crosby, Kholo, Brisbane, and Lockyer Valley. It is most common in areas of remnant habitat structure, such as the foothills of Mt Glorious and Brisbane Forest Park. It has also been recorded at Cannonvale in the Whitsundays region of North Queensland, in the Coffs Harbour region in late 2019, and north of Murwillumbah in the Far North Coast region of New South Wales in late 2021. In Southeast Queensland, it is found across a wide range of habitats and vegetation types, from coastal forest and woodland, to scrubland, mulga, and outback desert. It is also found in central New South Wales (Dubbo/Parkes), Lower North Coast New South Wales (Pacific Palms/Hunter Valley), White Rock and Spring Mountain Conservation Park near Ipswich, Queensland, and the south-eastern part of South Australia.
The bandy-bandy is oviparous, meaning it produces offspring inside eggs that hatch after laying. Females produce offspring seasonally, laying eggs in late summer (February – March) after undergoing vitellogenesis in October. Both live-bearing and oviparous Australian elapid snakes follow a similar seasonal reproductive cycle. Live-bearing elapids undergo ovulation in October – December and give birth in February – April after a 14-week gestation period. Oviparous elapids undergo ovulation at the same time (October – December), and their eggs are laid shortly after ovulation without a long gestation period. Newly hatched young emerge at the same time that live-bearing snakes give birth (February – March). However, there is evidence that oviparous elapids may be able to produce a second clutch of eggs in late summer, with newly hatched offspring emerging around April.
For V. annulata, the average clutch size is 7.7 offspring, and a single clutch can hold up to 13 offspring. Sexual dimorphism is visible in bandy-bandys, with females being much larger in size than males. In one study, female V. annulata had a mean snout-vent length of 54.4 cm, compared to 39.2 cm for males. In many reptiles, clutch size depends on the size of the mother. The advantages linked to higher fecundity can create selective pressure for female snakes to grow larger, but the relationship between increased clutch size and maternal size, and the intensity of this selection, varies between species. For the bandy-bandy, larger female size is thought to be caused by selective pressure on fecundity.
Male-male combat is a well-documented, common trait in many animals as a form of sexual selection, which creates selective pressure for males to grow larger. In an analysis of snakes, male size relative to female size was larger in snake species where male-male combat occurs. However, male-male combat is absent in bandy-bandys, so males are relatively small.
