A phylogenetic and biogeographic study of Euniphysa (Eunicidae, Polychaeta)

Fourteen species have either been described in, or referred to, the genus E uniphysa. Seven of these are here re-described based on type material and t wo new species, E. quadridentata and E. filibranchia, are described. Euniph ysa oculata is found to be a subjective synonym of E. spinea, and E. unicus a is a subjective synonym of E, aculeata. Euniphysa taiwanensis and E. mega lodus are correctly assigned to the genus, but cannot be described due to l ack of material. Euniphysa misakiensis, E. tubicola and E. tubifex are tran sferred to Eunice. A key is given to the nine identifiable species retained in Euniphysa. Coding strategies for polymorphic and inapplicable character s, as well as problems associated with shared absences, are discussed. A ph ylogenetic analysis of Euniphysa based on 24 morphological characters yield ed two most parsimonious trees (CI = 0.902, RI = 0.905). The tree topology separates Euniphysa into two distinct groups. Group I includes E. filibranc hia n. sp., E. italica, E. jeffreysii, E. quadridentata n, sp. and E. spine a, it is supported by five equivocal similarities. Group II is supported by five unequivocal synapomorphies and two equivocal similarities, it include s E. aculeata, E. auriculata, E. falciseta and E. tridontesa. Based on the phylogenetic topology, Paraeuniphysa and Heterophysa are considered as juni or synonyms of Euniphysa. The recognition of a separate Family for Euniphys a is not warranted. All species of Euniphysa are fragile, shallow, warm wat er species. They have been collected mainly from sandy sediments of the Nor thern Hemisphere. The greatest diversity is from the South China Sea area; other species are found throughout the Indian Ocean, the Mediterranean Sea and the East Atlantic Ocean coasts suggesting the genus may have originated in the Tethys Sea. A few species have also been found in the Gulf of Mexic o and the West Atlantic Ocean coast again suggesting a Tethyan origin assoc iated with the westward drift of the North American continent.