First insight into phylogeny of Hyalinoeciinae (Onuphidae) inferred from one mitochondrial and four nuclear markers

Hyalinoeciinae represent one of the two monophyletic subfamilies of onuphid polychaetes comprising six genera and ca. 80 species. They have a world-wide distribution from shallow subtidal areas to abyssal plains with greater species diversity in deep waters. Hyalinoeciins share a number of morphological and ontogenetic synapomorphies such as the position of subacicular hooks in parapodia, arrangement of nurse cells in oocytes or specific pattern of chaetal replacement in larval development. Although they can reach extremely high densities and are commonly found in trawl and sledge catches, none of the six genera has been the subject of comprehensive revisionary work and their species compositions and monophyletic status remain questionable. All members of Hyalinoeciinae demonstrate signs of progenesis in lacking a number of morphological characters normally present in adults of other onuphid genera. The body size and degree of character loss/underdevelopment varies in different genera and species, however it is not clear whether this variation is depth-related or not. A complete nuclear 18S rDNA (~1800 bp), ITS1 (~500 bp), ITS2 (~350 bp), a fragment of the nuclear 28S rDNA (~650 bp) and a fragment of the mitochondrial 16S rDNA (~500 bp) were amplified for nine species of Hyalinoeciinae representing four genera in order to assess their monophyly and investigate intrageneric relationships within the subfamily. Preliminary results show that Hyalinoecia and Nothria are monophyletic with strong node support while Neonuphis and Leptoecia form a joint monophyletic clade. Leptoecia+Neonuphis were sister to Hyalinoeca also sharing a number of morphological synapomorphies such as organic tubes and the absence of peristomial cirri.