Пилоспинная белла

Description[]

The female is considerably larger than the male, with a carapace 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.

References

1. ^ Gray, J.E. 1867. Description of a new Australian tortoise. Annals and Magazine of Natural History. 3(20):43-45
2. ^
3. ^ Ryan, Michelle, General Editor. (2000). Wildlife of Tropical North Queensland: Cooktown to Mackay. Queensland Museum. ISBN 0-7242-9349-3.
4. ^ Ehmann, Harold (1992). Encyclopedia of Australian Animals: Reptiles. Angus&Robertson. ISBN 0-207-17379-6 (Reptiles)
5. 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.
6. Thomson, S. & Georges, A. (2009) Myuchelys gen. nov. —a new genus for Elseya latisternum and related forms of Australian freshwater turtle (Testudines: Pleurodira: Chelidae) Zootaxa 2053: 32–42.
7. Georges, A. & Thomson, S. 2010. Diversity of Australasian freshwater turtles, with an annotated synonymy and keys to species. Zootaxa 2496: 1–37.
8. Freeman, Alastair and John H. Cann. “Myuchelys latisternum (Gray 1867) – Sawshelled Turtle, Saw-Shell Turtle.” (2014).
9. ^

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 n o indication of large congregates of nesting sites, but instead scene in ones or twos at dispersed localities along the watercourse. Nest have been seen in soil as far as 100m 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 X 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 x 22.5 mm.

Taxonomic history

The species M. latisternum was originally placed in the genus Elseya by Gray, 1867 but Elseya was redefined by Boulenger, 1889 to include species defined by the presence of an alveolar ridge. Hence, Myuchelys latisternum and Myuchelys novaeguineae were moved to the genus Emydura. In 1967, the two species were placed back in the genus Elseya by Goode, where they remained until recently.

During the time, the species Myuchelys bellii was basically lost to knowledge, having been misidentified as a South American species when described by Gray, 1844, and was in the genus Phrynops until this oversight was corrected by Cann, 1998. The species Myuchelys georgesi and Myuchelys purvisi were initially placed in the genus Elseya, but were identified as belonging to a unique clade along with Myuchelys latisternum and Myuchelys bellii using electrophoresis.

The first attempt to separate this group into its own genus was the genus Euchelymys (Gray, 1871), but this name was subsequently synonymised with Elseya by Boulenger (1889) and the name was made permanently unavailable when Lindholm (1929) set Euchelymys sulcifera (= Emydura macquarii) as the type species, effectively making the name Euchelymys a junior synonym of Emydura.

Another option investigated was the fossil form Pelocomastes, de Vis 1897; the species in this genus may have represented an extinct member of the latisternum group, but this was determined to be incorrect and the name Pelocomastes is now considered a junior synonym of Elseya.

The genus name Wollumbinia was erected by Wells, 2007, however, this paper was declared to be in breach of the ICZN code defining a valid publication, ICZN Articles 8 and 9 and Recommendation 8D. As such this name is not considered valid. The genus encompassing these species was named Myuchelys by Thomson and Georges, 2009. Currently, this arrangement is considered the accepted name for the latisternum group by the IUCN, multiple taxonomic checklists and by numerous workers in diverse disciplines. In the ensuing time the name Myuchelys has established usage as defined by the ICZN code, with many research papers using it and almost none using alternatives. It is therefore unlikely to be replaced and would require a decision of the ICZN now to do so.

In 2013, Le et al. found that one species, purvisi, was still paraphyletic and proposed a new monophyletic genus to handle this; purvisi was therefore moved to the genus Flaviemys. In 2017, the IUCN TTWG following the recommendation of Spinks et al. (2015) placed Flaviemys as a synonymy of Myuchelys.

References

1. ^
2. ^
3. ^ Gray, J. E. 1844. Catalogue of the Tortoises, Crocodiles and Amphibaenians in the Collection of the British Museum. London. Edward Newman. 80pp.
4. Cann, J. 1998a. Georges short-neck turtle. Monitor 9(1):18-23.
5. ^ Gray, J.E. 1867. Description of a new Australian tortoise. Annals and Magazine of Natural History. 3(20):43-45
6. ^ Boulenger, G.A. (1889) Catalogue of the Chelonians, Rhynchocephalians, and Crocodiles in the British Museum (Natural History). British Museum, London.
7. Goode, J. (1967) Freshwater Tortoises of Australia and New Guinea (in the Family Chelidae). Lansdowne Press, Melbourne.
8. Cann, J. (1998) Australian Freshwater Turtles. Beaumont Publishing, Singapore.
9. Gray, J.E. (1871) On Euchelymys, a new genus and two new species of Australian freshwater tortoises. Annals and Magazine
   of Natural History (London), Series 4, 8, 117–118.
10. Lindholm, W.A. (1929) Revidiertes Verzeichnis der Gattungen der rezenten Schildkröten nebst Notizen zur Nomenklatur einger Arten. Zoologischer Anzeiger, 81, 275–295.
11. de Vis, C.W. 1897. The extinct freshwater turtles of Queensland. Annals of the Queensland Museum. 3: 3-7.
12. ^
13. ^
14. ^
15. Fielder D, Vernes K, Alacs E, Georges A (2012) Mitochondrial variation among Australian freshwater turtles (genus Myuchelys), with special reference to the Endangered M. bellii. Endang Species Res 17:63-71
16. Georges A, Spencer RJ, Welsh M, Shaffer HB, Walsh R, Zhang X (2011) Application of the precautionary principle to taxa of uncertain status: the case of the Bellinger River turtle. Endang Species Res 14:127-134
17. Le, M., Reid, B., N., McCord, W., P., Naro-Maciel, E., Raxworthy, C., J., Amato, G., Georges A., 2013. Resolving the phylogenetic history of the short-necked turtles, genera Elseya and Myuchelys (Testudines: Chelidae) from Australia and New Guinea. Molecular Phylogenetics and Evolution. 68 (2013) 251–258.

Description

The female is considerably larger than the male, with a carapace 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.

References[]

1. ^ Gray, J.E. 1867. Description of a new Australian tortoise. Annals and Magazine of Natural History. 3(20):43-45
2. ^
3. ^ Ryan, Michelle, General Editor. (2000). Wildlife of Tropical North Queensland: Cooktown to Mackay. Queensland Museum. ISBN 0-7242-9349-3.
4. ^ Ehmann, Harold (1992). Encyclopedia of Australian Animals: Reptiles. Angus&Robertson. ISBN 0-207-17379-6 (Reptiles)
5. 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.
6. Thomson, S. & Georges, A. (2009) Myuchelys gen. nov. —a new genus for Elseya latisternum and related forms of Australian freshwater turtle (Testudines: Pleurodira: Chelidae) Zootaxa 2053: 32–42.
7. Georges, A. & Thomson, S. 2010. Diversity of Australasian freshwater turtles, with an annotated synonymy and keys to species. Zootaxa 2496: 1–37.
8. Freeman, Alastair and John H. Cann. “Myuchelys latisternum (Gray 1867) – Sawshelled Turtle, Saw-Shell Turtle.” (2014).
9. ^

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 n o indication of large congregates of nesting sites, but instead scene in ones or twos at dispersed localities along the watercourse. Nest have been seen in soil as far as 100m 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 X 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 x 22.5 mm.