Wirrah did you go: A taxonomic evaluation of Acanthistius ocellatus, the Eastern Wirrah, and Acanthistius paxtoni, the Orangelined Wirrah

Younis Menkara

Honours Candidate, University of Sydney

Supervisors: Prof Simon Ho (USyd) and Dr Anthony Gill (AM, USyd)

There are over 16,000 species of fish that inhabit the Earth’s marine environments. Despite this, many more remain undescribed or even undiscovered. Integrative taxonomy provides and effective means of classifying and documenting this diversity, especially when species are morphologically cryptic. In this study, I evaluate the taxonomic statuses of Acanthistius ocellatus, the Eastern Wirrah, and Acanthistius paxtoni, the Orangelined Wirrah. The genus Acanthistius has been problematic since its inception, acting as a ‘wastebasket’ for anomalous serranids. I aim to determine if there is a cryptic species complex within A. ocellatus and understand why A. paxtoni has not been observed since its description in 1982.

I perform principal component analyses of morphological characters and conduct phylogenetic analyses of mitochondrial sequences. I find no evidence for a cryptic species complex within A. ocellatus and show that there are considerable differences in the morphology of A. ocellatus and A. paxtoni. I estimate the crown ages of the sampled species of Acanthistius and find that A. ocellatus and A. cinctus are very closely related. Based on the results of my analyses, I hypothesise that A. paxtoni is the hybrid offspring of A. ocellatus and A. cinctus.