DNA barcodes and species identifications in Ross Sea and Southern Ocean fishes

The Southern Ocean occupies about 10 % of the world's oceans but has low species richness with only similar to 1.5 % of the marine fishes. Within the Southern Ocean, the Ross Sea region is one of the least exploited sea areas in the world, but is subject to commercial fishing. The fauna are not well known, and preliminary IPY molecular studies have indicated that species diversity has been underestimated in this region. DNA barcodes of fishes from the Ross Sea region were compared with barcodes of fishes from the Atlantic and Indian Ocean sectors of the Southern Ocean. Barcoding resolved 87.5 % of 112 species that typically exhibited high inter-specific divergences. Intra-specific divergence was usually low with shared haplotypes among regions. The Zoarcid Ophthalmolycus amberensis showed shallow divergences (0.1 %) within the Ross Sea and Australian Antarctic Territory but high inter-region divergence (2 %), indicative of cryptic species. Other potential cryptic species with high intra-specific divergences were found in Notolepis coatsi and Gymnoscopelus bolini. In contrast, several taxa showed low inter-specific divergences and shared haplotypes among morphological species. COI provided limited phylogenetic resolution of the genera Pogonophryne and Bathydraco. Trematomus loennbergii and T. lepidorhinus shared COI haplotypes, as previously noted in other regions, as did Cryodraco antarcticus and C. atkinsoni. There was a marked lack of congruence between morphological descriptions and COI divergences among the Ross Sea liparids with shallow or zero divergences among recently described species. Barcodes for the Ross Sea fishes highlighted several initial misidentifications that were corrected when specimens were re-examined.