A new species of freshwater turtle of the genus Elseya (Testudinata: Pleurodira: Chelidae) from the Northern Territory of Australia

Abstract

The genus Elseya has had a checkered taxonomic history, but is now restricted to species characterized by an alveolar ridge on the triturating surfaces of the jaw. The Australian forms were once regarded as a single widespread species extending from the Mary River of south-eastern Queensland to the Fitzroy River of north Western Australia, but a number of Australian species have now been identified based on a combination of molecular and morphological data-Elseya dentata, E. irwini, E. lavarackorum and E. albagula. The genus is represented in New Guinea by E. branderhorsti, E. novaeguineae, E. schultzii, and E. rhodini. One additional Australian taxon first identified in 1981 and subsequently established as a distinct taxon by molecular studies, is described here. It is a large chelid turtle that can be distinguished from all other Australian members of the genus Elseya by the distinctive cream or yellow plastron, free of the dark streaking, blotches or suffusing present in other species; an extensive bridge with little or no abrupt angle between the bridge and the ventral surface of the plastron; a head shield broken into a series of small plates rather than a single unit; flat uncornified temporal scales; and a narrower, less robust skull. Osteologically, it can be distinguished from Elseya dentata by the contact of the vomer and the pterygoids. The carapace is typically a light to medium brown in color whereas the carapace of Elseya dentata is typically dark brown to almost black in color. Distribution is the Mary, South Alligator, East Alligator, Goyder and Mann River drainages of the north east of the Northern Territory, Australia. It does not appear to be in sympatry with any other member of Elseya. It is, however, in sympatry with three species of Chelodina, at least two species of Emydura, Myuchelys latisternum and Carettochelys insculpta.

Turtles of the World: Annotated Checklist and Atlas of Taxonomy, Synonymy, Distribution, and Conservation Status (8th Ed.)

“…Elseya flaviventralis: Allopatric populations of the Elseya dentata group from the Arnhem Land region of Northern Australia were first suggested to be unique by Legler (1981) based on morphology. Subsequent allozyme electrophoretic analyses by Adams (1992, 1996) and morphological work by several authors (reviewed in Thomson and Georges 2016) supported the distinction of these populations at the species level, and Thomson and Georges (2016) formally described this species as Elseya (Elseya) flaviventralis, which we accept.…”

Further evidence in support of the recognition of the Freshwater Turtle Elseya oneiros (Testudines: Chelidae) from the Nicholson and Gregory Rivers of Northern Queensland

“…Since then, considerable progress has been made in the understanding of morphological characters and interspecies relationships of Australian chelids, especially within the genus Elseya (Thomson et al 2015, Thomson andGeorges 2016). In 2020, Joseph-Ouni et al proposed an alternative interpretation to that of conspecificity between the living species of Elseya in the Nicholson-Gregory drainages and the Riversleigh fossil turtle, utilizing a suite of 16 scutation characters (eight for each of the carapace and plastron) to assess differences between the fossil and extant populations.…”

Mitogenomics of historical type specimens of Australasian turtles: clarification of taxonomic confusion and old mitochondrial introgression

“…Compared to other continents, the Australasian turtle fauna is poorly known and significant progress has been made only recently 10–21 . Taxonomic assessment of Australasian chelids is impeded by two issues.…”