Biodiversity and Phylogeny of North Atlantic Euphrosinidae (Annelida)

Abstract

Euphrosinidae (Amphinomida) is a clade of generally small, short but stout annelids characterized by long, calcareous chaetae that may be distally forked or ringent. Little is known about the diversity of Euphrosinidae from the North Atlantic and the phylogeny of the group has received little attention. Here, we examined 59 specimens of Euphrosinidae (primarily from the IceAGE I and II cruises) and sequenced fragments of the mitochondrial 16S rDNA and nuclear 28S rDNA genes to improve understanding of euphrosinid diversity in the North Atlantic and gain insights into euphrosinid phylogeny. Maximum likelihood analysis of 28S + 16S recovered Euphrosine as a ‘basal’ paraphyletic grade; a clade containing E. armadillo (plus other unidentified specimens) was sister to Euphrosinopsis + Euphrosinella while a clade containing E. aurantiaca and E. foliosa (plus three unidentified species) was recovered sister to all other sampled Euphrosinidae species. Species delimitation analyses based on 16S sequences identified between 14 and 11 species of Euphrosinidae with as many as ten distinct species from the North Atlantic. The IceAGE material investigated includes one new species of Euphrosinopsis and at least one new species of Euphrosinella. Unfortunately, because most of this material was preserved in ethanol, we were unable to characterize key features needed for adequate species descriptions. Additionally, PCR contaminants from presumed gut contents suggest that some euphrosinids eat other annelids, namely Cirratulidae and Syllidae.