DOI: 10.3897/vz.75.e150370

Authors: Christian Kehlmaier, Uwe Fritz, Gerald Kuchling

Abstract: Abstract Using mitochondrial genomes and nine nuclear loci, we examined genetic variation in snake-necked turtles (Chelodina sensu lato), with a focus on northern Australian taxa. The mitochondrial phylogeny of the genus is confounded by multiple introgression events, rendering the subgenera Chelodina sensu stricto and Chelydera non-monophyletic. However, in the analyses of our nuclear dataset (6071 bp), the recognition of the subgenera is supported. The morphologically most distinct taxa (Chelodina expansa, C. longicollis, C. oblonga, C. parkeri, C. steindachneri) are well differentiated genetically. However, many other species are not or only weakly distinct, calling their validity into question. Our dataset includes sequences from historical museum material and the holotype of C. kuchlingi, a species currently listed as Critically Endangered by the Biodiversity Conservation Act of Western Australia. Resequencing its mitogenome using protocols optimized for formalin-preserved specimens provides evidence that the formerly reported mitochondrial distinction of C. kuchlingi was based on a sequencing artifact. Two historical specimens of C. kuchlingi are genetically indistinguishable from snake-necked turtles living today on the Ord River floodplain. In addition, C. walloyarrina, a geographically close taxon with introgressed mitochondria from another species, is not differentiated on the nuclear genomic level. We conclude that Chelodina walloyarrina (McCord & Joseph-Ouni, 2007) is a junior synonym of Chelodina kuchlingi Cann, 1997 and that the extant snake-necked turtles from the Ord River floodplain are conspecific. This implies that morphological traits used in the past to diagnose the involved taxa are less important than previously thought. The redefined species C. kuchlingi is distributed on the sandstone plateau and associated escarpments as well as on the lowland coastal plains of the Kimberley region of tropical northern Australia. It no longer qualifies as Critically Endangered and has to be downlisted, pending a new status evaluation. Our results underline the importance of a robust taxonomy for conservation decisions. Further research is warranted to examine the validity of the remaining weakly differentiated Chelodina taxa, which could not be resolved in our analyses.

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DOI: 10.3897/vz.73.e99495

Authors: Scott A. Thomson, Natália R. Friol, Arthur White, Dion Wedd, Arthur Georges

Abstract: Disagreement exists on the taxonomic identity of the extant populations of the Australian Elseya referred to in 1992 as the gulf Elseya (= Elseya sp. aff. dentata [Nicholson]). The extant form has since 1997 been considered conspecific with the late Pleistocene fossil Elseya lavarackorum (White and Archer, 1994). Recently it has been considered a new species, Elseya oneiros Joseph-Ouni et al., 2020, conspecific with another fossil found in the same site and stratum as Elseya lavarackorum. Here we re-examine the fossil material and reassess the characters used by previous authors in an attempt to decide the issue. We find that the anterior bridge suture with the carapace of the fossil Elseya lavarackorum is associated with extensive and prominent plastral elements, which has led to misinterpretation of characters associated with this structure. We furthermore show that interindividual variation in sulci patterns is so great as to render them of little taxonomic value. On the basis of (a) deviation of the anterior shape of the carapace from ovoid such that, in aged individuals, the most anterior point of the carapace occurs at marginal scutes M2 (a resultant nuchal bay occurs in such individuals); (b) the typical absence of a cervical scute; (c) no evidence of a medial constriction in the anterior bridge strut suture; and (d) absence of evidence of any other informative variation of taxonomic value; we conclude that the decision to consider the late Pleistocene (ca 23 kyr old) fossil and the extant Elseya sp. aff. dentata [Nicholson] as Elseya lavarackorum (White and Archer, 1994) as conspecific should stand.

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