Phylogenetic relationships within Nereididae (Annelida : Phyllodocida)

Abstract

Nereididae Johnston, 1865, part of the large clade Phyllodocida, is one of the best-known annelid groups. Presently, there are some 500 nominal species grouped into 42 genera, although there is little consensus among different authors as to how they should be classified. The relationships of nereidids were assessed in a morphology-based parsimony analysis of 41 terminal taxa, with members of Chrysopetalidae and Hesionidae used as outgroups. Type species for the majority of currently recognised nereidid genera were used as terminal taxa, and character information was based on examination of type and non-type specimens, together with literature descriptions. High degrees of homoplasy were found for several features that are traditionally applied to delineate subgroups of Nereididae, including the presence of paragnaths and the distribution of different kinds of chaetae. Six major groups were recovered: Namanereidinae, including Namalycastis and Namanereis, characterised by spherical shape of palpostyles and ventrally displaced notoaciculae; one clade corresponding in part to previous authors concepts of Nereidinae, including Nereis, Eunereis, Hediste and Platynereis (the relationships of several well known nereidids, such as Neanthes and Perinereis, commonly referred to Nereidinae, could not be unambiguously resolved); one unnamed and not previously recognised clade (A), including Australonereis, Laeonereis, Dendronereides and Olganereis, characterised by the presence of papillae on the maxillary ring; a second unnamed clade (B), including Leptonereis, Sinonereis, Tylonereis and Tylorrhynchus, characterised by enlarged notopodial ligulae; a well supported Gymnonereidinae, restricted to Ceratocephale, Gymnonereis, Tambalagamia and Micronereides; and a third unnamed clade (C), including Ceratonereis, Solomononereis, Unanereis, Cheilonereis and Websterinereis, characterised by unilobated neuropodial postchaetal lobes. Among these groups we found good support for the Namanereidinae, the Gymnonereidinae and for the whole of Nereididae. The subfamilies Dendronereidinae and Notophycinae (based on Micronereis, senior synonym of Notophycus) are regarded here as monotypic.