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We used mitochondrial (COI) and nuclear (Histone H3) genome markers to test the hypothesis that the diversity of Treptopale (Annelida: Chrysopetalidae) in northern Australia comprises more than the two currently known species recently described based on morphology. The molecular phylogeny reveals nine clades. The Treptopale homalos species complex comprises: T. homalos sensu stricto, the only clade occurring all around northern Australia (from Heron Island to Ningaloo Reef); Clade 8 found only at Ningaloo Reef; Clade 2 found only on the Great Barrier Reef and described here as new. Treptopale magdae sp. nov. can be distinguished morphologically by the smaller number of internal ribs of the lateral, main and medial paleael notochaetae. The diverse Treptopale paromolos species complex comprises six clades: Clade 3, Treptopale paromolos sensu stricto and Clade 5 are only found on Australia's NW coast; Clades 4, 6 and 9 are found only in NE Australia. Molecular phylogenetic relationships, especially ...

DNA barcoding potentially offers scientists who are not expert taxonomists a powerful tool to support the accuracy of field studies involving taxa that are diverse and difficult to identify. The taxonomy of rays has received reasonable attention in Australia, although the fauna in remote locations such as Ningaloo Reef, Western Australia is poorly studied and the identification of some species in the field is problematic. Here, we report an application of DNA-barcoding to the identification of 16 species (from 10 genera) of tropical rays as part of an ecological study. Analysis of the dataset combined across all samples grouped sequences into clearly defined operational taxonomic units, with two conspicuous exceptions: the Neotrygon kuhlii species complex and the Aetobatus species complex. In the field, the group that presented the most difficulties for identification was the spotted whiptail rays, referred to as the ‘uarnak’ complex. Two sets of problems limited the successful application of DNA barcoding: (1) the presence of cryptic species, species complexes with unresolved taxonomic status and intra-specific geographical variation, and (2) insufficient numbers of entries in online databases that have been verified taxonomically, and the presence of lodged sequences in databases with inconsistent names. Nevertheless, we demonstrate the potential of the DNA barcoding approach to confirm field identifications and to highlight species complexes where taxonomic uncertainty might confound ecological data.