Phylogeny and Cryptic Diversity of Diopatra (Onuphidae, Annelida) in the East Atlantic

Diopatra Audouin & Milne-Edwards, 1833 is a species rich genus that is common in tropical and subtropical regions. The genus is readily identified by its striking, spiral branchiae, but species identification has historically been challenging due to a high variation in diagnostic characters used. This study aims to reconstruct the phylogeny of Diopatra with molecular markers and assess the species diversity of West African Diopatra with the species delimitation programs bPTP and BPP. Specimens were collected from Morocco to Angola, and the markers COI, 16S and 28S were sequenced from 76 specimens. The constructed phylogeny retrieved Diopatra as monophyletic, as well as five well supported clades within the genus. All clades were defined by morphological characters, some of which have previously not been considered to have high phylogenetic or taxonomical value. Species delimitation analyses recovered 17 new species, several of which were not readily identified morphologically. One species complex comprising between one and 12 species was left unresolved due to incongruence between the species delimitation methods and challenging morphology. Our results indicate that the diversity of Diopatra is significantly underestimated, where this regional study near to doubled the number ofknown species from the East Atlantic.