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

Abstract

Thomson et al. (1997) proposed that the extant Elseya from the Nicholson-Gregory drainages in northwestern Queensland was conspecific with the holotype of Elseya lavarackorum, which comprised a fossil carapace and associated plastron excavated from the late Pleistocene Terrace Site at Riversleigh. Analysis of additional fossil material, and examination of a suite of 16 scute characters (eight for each of the carapace and plastron) by Joseph-Ouni et al. (2020) concluded that the two species were distinct and represented separate Elseya lineages and proposed the new name Elseya oneiros for the extant lineage. Recently, the Turtle Taxonomy Working Group (TTWG) in their 9th edition Checklist of Turtles of the World (TTWG 2021) questioned the status of E. oneiros and placed it in the synonymy of E. lavarackorum, making the claim, amongst others, that the skeletal characters of Thomson et al. (1997) were not addressed. Here we fully address the claims made and evaluate those skeletal characters. We also assess an additional nine thoracic skeletal characters of the pertinent Elseya species, including E. dentata sensu stricto. The results again do not support the conclusions of Thomson et al. (1997) of the holotype of Elseya lavarackorum being conspecific with the extant Elseya from the Nicholson-Gregory Rivers, reaffirms the proposal offered by Joseph-Ouni et al. (2020) for the placement of E. lavarackorum in the subgenus Elseya, and the status of E. oneiros in the Nicholson-Gregory drainages as a distinct species.