DNA barcoding reveals hidden nemertean diversity from the Marine Protected Area Namuncurá-Burdwood Bank, Southwestern Atlantic

Abstract

The implementation of molecular data for the analysis of nemertean diversity has unraveled the taxonomic status of several species and many higher taxa within the group. Nowadays, a large proportion of novel putative species are being discovered and it is necessary to add molecular data to the morphological description to obtain a correct identifcation. In this study, we used mitochondrial cytochrome oxidase I gene (COI) as molecular marker to investigate the diversity of nemerteans from a marine Sub-Antarctic environment. We used Automatic Barcode Gap Discovery (ABGD), Poisson Tree Processes (PTP) and Bayesian implementation of the PTP model (bPTP) as well as reciprocal monophyly on neighbor-joining (NJ) and maximum likelihood (ML) trees for species delimitation. ABGD showed a clear barcoding gap (6 to 10%) and the presence of 15 diferent putative nemertean species in the dataset of 54 COI sequences from the marine protected area “Namuncurá–Burdwood Bank” (MPA-BB), expanding the known biodiversity for the Sub-Antarctic region. Ten monostiliferan and five heteronemertean species were found. Our results also confirm the presence of two Parborlasia corrugatus cryptic species in the Antarctic and Sub-Antarctic region. This work highlights the importance of the MPA-BB as a biodiversity hotspot and provide molecular data for the Phylum Nemertea in the Southwestern Atlantic Ocean.