Inference of phylogenetic relationships within Fabriciidae (Sabellida, Annelida) using molecular and morphological data.

Cladistic relationships among fabriciids have to date been explored in the context of adult morphology, but resolution has been declining as more species are described. In this study, we incorporated data on the reproductive system, including features related to the male sperm and sperm storage by females, to supplement existing data on adult morphology (for a total of 50 characters). Three nuclear DNA markers (18S rDNA approximately 1800 bp, the D1 region of 28S rDNA approximately 320 bp, and histone H3 approximately 330 bp) were sequenced from 21 species of fabriciids. We assessed the phylogeny of Fabriciidae based on an integrative analysis of these morphological and molecular characters. Our results show that, in addition to three previously recovered apomorphies for Fabriciidae (absence of ventral lips, modification of abdominal uncini to an elongate manubrium, and presence of branchial hearts), six more apomorphies associated with the reproductive system can be used to support this clade-spermiogenesis only in the thorax, spermiogenesis in large clusters with a central cytophore, single dorsal sperm duct, sperm nuclear projection, thickening of the sperm nuclear membrane and the sperm extra-axonemal sheath. The results require the erection of two new genera and two new species, which are described. © The Willi Hennig Society 2010.