DNA barcoding supports identification of species (Nemertea: Hoplonemertea).

BACKGROUND

Nemerteans of the genus live inside of the mantle cavity of marine bivalves. The genus currently contains only six species, five of which are host-specific and usually found in a single host species, while the sixth species, , has a wide host range and has been found in 27 different bivalve species to date. The main challenge of species identification resides in the similarity of the external morphology between species (terminal sucker, gut undulations number, anus position and gonad colouration), and thus, the illustrations provided in the original descriptions do not allow reliable identification. In this article, we analyse the relationships amongthree species of :, and,adding new data for the and reporting the first for , analysing 658 base pairs of the mitochondrial cytochrome oxidase subunit I gene().Based on these analyses, we present and discuss the potential of DNA barcoding for species identification.

RESULTS

Sixty-four DNA barcoding fragments of the mitochondrial gene from three different species (, ) are analysed (24 of them newly sequenced for this study, along with four outgroup specimens) and used to delineate species. Divergences, measured as uncorrected differences, between the three species were -11.73%,- 10.62%and - 10.97%. The mean intraspecific divergence within the ingroup species showed a patent gap with respect to the interspecific ones: 0.18% for ,0.13% for and0.02% for (rangesfrom 0 to 0.91%).

CONCLUSIONS

We conclude that there is a clear correspondence between the molecular data and distinguishing morphological characters. Our results thus indicate that some morphological characters are useful for species identification and support the potential of DNA barcoding for species identification in a taxonomic group with subtle morphological external differences.