The saw-shelled turtle (''Myuchelys latisternum'') is a species of

turtle Turtles are an order of reptiles known as Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked tu ...

in the

Chelidae Chelidae is one of three living families of the turtle suborder Pleurodira, and are commonly called Austro-South American side-neck turtles. The family is distributed in Australia, New Guinea, parts of Indonesia, and throughout most of South Amer ...

family

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

, ranging along rivers and streams and connected swamps and lagoons from coastal

Cape York Peninsula Cape York Peninsula is a large peninsula located in Far North Queensland, Australia. It is the largest unspoiled wilderness in northern Australia.Mittermeier, R.E. et al. (2002). Wilderness: Earth’s last wild places. Mexico City: Agrupación ...

to northern

New South Wales ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...

, with populations also noted as far south as Newcastle - (Williams River Catchment site of the former Tilligra Dam). They are thought to have been introduced to Lake Eacham in the

Atherton Tablelands The Atherton Tableland is a fertile plateau which is part of the Great Dividing Range in Queensland, Australia. The principal river flowing across the plateau is the Barron River. It was dammed to form an irrigation reservoir named Lake Tinar ...

. Other common English names are: serrated snapping turtle or common sawshell turtle.Ryan, Michelle, General Editor. (2000). ''Wildlife of Tropical North Queensland: Cooktown to Mackay''. Queensland Museum. .Ehmann, Harold (1992). ''Encyclopedia of Australian Animals: Reptiles''. Angus&Robertson. (Reptiles)

Description

The female is considerably larger than the male, with a

carapace A carapace is a Dorsum (biology), dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tor ...

up to 28 cm long compared to the males which rarely get longer than about 18 cm. The carapace is roughly oval and broad at the rear. They are not usually aggressive, but can bite fiercely. They can also emit a strong smell. The shell has marginal serrations which are the reason for its common name. It retains some of these serrations throughout its life. "The head shield extends down the side of the head to just above the tympanum, and the top of the neck has prominent pointed tubercules (many of these with an apical sensory pit)." The carapace is mainly brown to dark brown, commonly with some dark blotches. The plastron (underside) is yellowish. The head is large with a projecting snout and a horny plate on the top. The neck can fold sideways. The feet are webbed and also clawed. Hatchlings have serrated hind legs which become smooth as they mature.

Nomenclatural history

''Myuchelys latisternum'' (Gray, 1867) (common sawshell turtle) * 1867 ''Elseya latisternum'' Gray, 1867, holotype, BMNH 1947.3.4.13, from North Australia. * 1871 ''Euchelymys spinosa'' Gray, 1871, holotype, BMNH 1946.1.22.77, from North Australia. Synonymy follows that of Gray (1872a) and Boulenger (1889).Gray, J.E. 1871. On ''Euchelymys'' a new genus and two new species of Australian freshwater tortoises. ''Annals and Magazine of Natural History''. (4)8:117-118. * 2009 ''Myuchelys latisternum'' — Thomson & Georges, 2009Thomson, S. & Georges, A. (2009) ''Myuchelys'' gen. nov. —a new genus for ''Elseya latisternum'' and related forms of Australian freshwater turtle (

Testudines Turtles are an order (biology), order of reptiles known as Testudines, characterized by a special turtle shell, shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) an ...

Pleurodira The Pleurodira are one of the two living suborders of turtles, the other being the Cryptodira. The division between these two suborders represents a very deep evolutionary divide between two very different types of turtles. The physical differen ...

: Chelidae) ''Zootaxa'' 2053: 32–42. First use of combination. The combination ''Wollumbinia latisternum'' (Gray, 1867)

Wells Wells most commonly refers to: * Wells, Somerset, a cathedral city in Somerset, England * Well, an excavation or structure created in the ground * Wells (name) Wells may also refer to: Places Canada *Wells, British Columbia England * Wells ...

, 2007, was declared unpublished and hence unavailable for use by Fritz & Havaš 2007.Georges, A. & Thomson, S. 2010. Diversity of Australasian freshwater turtles, with an annotated synonymy and keys to species. ''Zootaxa'' 2496: 1–37.

Reproduction and nesting

''Myuchelys latisternum'' reaches sexual maturity at an SCL of 125–135 mm in males and 182–189 mm in females. Courtship behaviors continue throughout the year but mating is observed during mid January. There is no indication of large congregates of nesting sites, but instead, they are seen in ones or twos at dispersed localities along the watercourse. Nest have been seen in soil as far as 100 m from the water. The females nest from September to December. They can have three to four clutches in one season of 9 to 20 eggs which hatch before winter in about 60 days, with the incubation period shortened in southern regions. The eggs are variably described as either "hard-shelled (34 × 22 mm)", or as small and "flexible-shelled". Hatchlings from central Queensland measured 30 x 29 mm SCL x carapace width, while hatchlings from northern New South Wales averaged 32.5 × 22.5 mm.

Feeding habits

The saw-shelled turtle is an opportunistic omnivore with a carnivorous preference. It feeds on fish, tadpoles, frogs, bivalves, crustaceans, snails, carrion, and aquatic and terrestrial insects. It is also one of the few native Australian animals successful in preying on the introduced and very poisonous

cane toad The cane toad (''Rhinella marina''), also known as the giant neotropical toad or marine toad, is a large, terrestrial true toad native to South and mainland Central America, but which has been introduced to various islands throughout Oceania ...

(''Rhinella marina'') which is lethal to many freshwater turtles. Toads too large to swallow whole are first shredded with their front claws. They also eat vegetation including fruits, leaves, filamentous algae, and water weed.

Behaviour

Like many other aquatic turtles, the saw-shelled turtle is able to obtain oxygen from water through skin, cloaca, and buccopharyngeal cavity, thus extending its ability to stay under water for prolonged periods.

Habitat and ecology

''Myuchelys latisternum'' is most often located in headwaters or tributaries of larger rivers in creeks, waterholes, dams, and lakes. However they are a highly adaptable species and have been seen in a variety of landscapes such as savannah woodlands, tropical rainforest, farmland, and semi-urban environments. Can be observed on logs and rocks adjacent to their habitat for basking, it is unknown if this is for thermoregulatory purposes or not.

References

External links

Images of saw-shelled turtlesGondwanan Turtle Site
{{Taxonbar, from=Q2716602 Myuchelys Turtles of Australia Endemic fauna of Australia Reptiles described in 1867 Taxa named by John Edward Gray