About Myuchelys latisternum (Gray, 1867)
Myuchelys latisternum shows strong sexual size dimorphism: females grow considerably larger than males. Females can reach a carapace length of up to 28 cm, while males rarely exceed around 18 cm in length. The carapace is roughly oval in shape and broad at the rear. This species is not usually aggressive, but it can bite fiercely when threatened, and it can also emit a strong odor. The shell has marginal serrations, which is the trait that gives the species its common name; individuals retain some of these serrations across their entire lifespan. The head shield extends down the side of the head to just above the tympanum, and the upper surface of the neck has prominent pointed tubercles, many of which have an apical sensory pit. The carapace is mostly brown to dark brown, and commonly marked with scattered dark blotches. The plastron, the underside of the shell, is yellowish. Individuals have a large head with a projecting snout, and a horny plate on the top of the head. The neck can fold sideways. The feet are both webbed and clawed. Hatchlings have serrated hind legs that smooth out as they mature. Myuchelys latisternum is most commonly found in headwaters or tributaries of larger rivers, including creeks, waterholes, dams, and lakes. It is a highly adaptable species, and has been recorded across a range of landscapes including savannah woodlands, tropical rainforest, farmland, and semi-urban environments. Individuals can often be seen basking on logs and rocks adjacent to their aquatic habitat; it remains unknown whether this basking behavior serves a thermoregulatory purpose. Males of this species reach sexual maturity when they have a straight carapace length (SCL) of 125–135 mm, while females reach sexual maturity at an SCL of 182–189 mm. Courtship behaviors occur year-round, but mating has only been observed in mid-January. Nesting sites are not found in large groups; instead, nesting individuals are typically seen alone or in pairs at dispersed locations along watercourses. Nests have been found in soil up to 100 meters away from the water. Females nest between September and December each year. They can produce three to four clutches per nesting season, each containing 9 to 20 eggs. Eggs hatch in approximately 60 days, before the start of winter; the incubation period is shorter in southern parts of the species' range. Descriptions of egg structure vary: some sources note eggs are hard-shelled, measuring 34 × 22 mm, while others describe eggs as small and flexible-shelled. Hatchlings from central Queensland measure 30 × 29 mm (SCL × carapace width), while hatchlings from northern New South Wales average 32.5 × 22.5 mm in the same measurements.
