Elseya dentata (GRAY, 1863)
Can you confirm these amateur observations of Elseya dentata?
|Higher Taxa||Chelidae, Chelodininae, Pleurodira, Testudines (turtles)|
|Common Names||Northern Australian Snapping Turtle|
|Synonym||Chelymys dentata GRAY 1863: 98|
Chelymys elseyi GRAY 1864:132 (nomen nudum)
Chelymys elseya GRAY 1870: 76 (nomen nudum)
Elseya dentata — GRAY 1867
Elseya intermedia GRAY 1872: 23
Elseya dentata — BOULENGER 1889
Elseya dentata — COGGER 2000: 194
Elseya flaviventralis GEORGES et al. 2000: 7 (nomen nudum)
Elseya dentata — GEORGES & THOMSON 2010
Elseya (Elseya) dentata — THOMSON et al. 2015
Elseya (Elseya) dentata — TTWG 2017: 194
|Distribution||N Australia (from the Kimberley district of Western Australia eastward through the Northern Territory to the Roper River of eastern Northern Territory)|
Type locality: Beagle’ s Valley, upper Victoria River, N. T. (15 ̊ 34' S, 130 ̊ 54' E)
intermedia: Type locality: upper part of Victoria River, NT, Australia.
|Types||Lectotype: BMNH 1922.214.171.124 (designated by THOMSON et al. 2015); Syntypes: BMNH 19126.96.36.199 (probable holotype), BMNH 19188.8.131.52|
Holotype: BMNH 19184.108.40.206 [intermedia]
|Diagnosis||Diagnosis (genus): The members of the genus Elseya can be diagnosed by the following combination of external characters—head and neck, when extended, much shorter than the carapace; gular scutes entirely separated by the intergular scute; prominent alveolar ridge on the triturating surfaces of the jaw sheaths (secondarily reduced in Elseya schultzei, E. novaeguineae and E. rhodini); a horny casque (head shield) on top of the head of adults, entire, fragmented or deeply fenestrated; temporal region covered with prominent scales; front feet with five claws, rear with four claws. The anterior bridge strut of Elseya is angled sharply (approx. 45°) away from the rib/gomophosis of pleural one, a character shared with Emydura but excluding Elusor, Pseudemydura, Rheodytes, Myuchelys and Flaviemys. The anterior and posterior sides of the anterior bridge suture in Elseya are widely spaced both proximally and distally, with or without a medial constriction, whereas in Emydura only the proximal end of the suture is expanded followed by immediate constriction to a diameter confluent with the peripheral part of the bridge suture [from THOMSON et al. 2015].|
Diagnosis (dentata): Elseya dentata is a large species of freshwater turtle of the Family Chelidae that is readily identified by the following combination of characters: The head is very broad and deep, with a very wide mandibular symphysis and a distinct median alveolar ridge on the upper jaw. The horny plate on top of the head does not extend laterally and there are two small white barbels under the chin. The neck is large and muscular with scattered enlarged conical tubercles over a covering of smaller flat tubercles. The mature carapace is robust, thick and smoothly rounded anteriorly, generally oval in shape and with some posterior expansion. Additionally, there is slight upturning at the lateral marginals but the posterior of the carapace is largely un-serrated. In general shape, the posterior margin of the carapace is acutely tapered, not at all rounded in shape. The plastron is always long and relatively narrow, being widest at the bridge and gently tapering both anteriorly and posteriorly, although the anterior plastral lobe does tend to slightly widen with age. The intergular shield completely separates the gulars, and is longer than wide, and much narrower than the adjacent gular shields. Hatchlings differ somewhat in that they have a noticeably serrated posterior margin to the carapace and fairly prominent central ridging (both characters which are lost with age), and some lateral upturning to the carapace as well. In immature specimens, the carapace is pale to light brown, but with age it changes to very dark brown in colouration. Mature individuals have the dorsal colour of the head and neck a uniform dark greyish-brown, and no facial striping, however laterally these areas are much paler - and may even have a piebald or blotched pattern, to being almost totally white in some older specimens. The iris is brownish, with a very light inner ring and is distinctly flecked with darker brown, and usually the tympanic region is whitish also. The ventral colouration is distinctly variegated or piebald in pattern in both sexes, unlike other members of the dentata-complex which are either very pale or very dark and usually unpatterned. Elseya dentata attains a maximum carapace length of around 340mm, but this size would be exceptional, as most mature specimens are only about 280-300mm [from WELLS 2007].
Diagnosis (dentata): Large short-necked chelid turtle. Juveniles have moderately spinose shells, reducing in prominence with age; many large adults with entire margin to the shell. Dark streaks or mottling of the otherwise cream plastron; carapace dark brown, almost black. Head shield entire, not as extensive or as fenestrated as the head shields of members of subgenus Pelocomastes. The alveolar ridge is moderate and does not increase the width of the triturating surface of the upper jaw in adults. Can be distinguished from all members of subgenus Pelocomastes by the medial constriction of the anterior bridge strut suture [from THOMSON et al. 2015].
Diagnosis (jukesi): see WELLS 2002.
|Comment||Type Species: Chelymys dentata GRAY 1863 is the type species of the genus Elseya GRAY 1867.|
Fossil species: E. (Pelocomastes) nadibajagu Thomson and Mackness, 1999 (Pliocene) and Elseya (Pelocomastes) uberrima (de Vis, 1897) (reviewed by Thomson, 2000) (Pleistocene) are fossil species of the genus Elseya.
WELLS 2007 and a few other authors also consider E. jukesii WELLS 2002 and Elseya stirlingi Wells and Wellington, 1985 as valid. Fritz & Havas (2007:162) and Georges & Thomson (2010) do not accept the description of jukesi as acceptable as it was published privately.
Habitat: freshwater (rivers, swamps)
|Etymology||Named after the dentate margin of the shell of younger animals.|
The specific epithet of 'jukesi' honours Australian naturalist Brian Jukes, a past resident of the area where this species lives. [from wELLS 2007].