A new species of Synelmis Chamberlin, 1919 (Annelida, Polychaeta, Pilargidae), Synelmis knoxi n. sp., is described from the continental shelf and slope of New Zealand. The new species differs from others of the genus in having relatively long cirriform antennae with the lateral ones arising over the mid-palps, cirriform tentacular and parapodial cirri, relatively thick amber-coloured notopodial spines starting on chaetigers 4 to 6, and 2 or 3 notoaciculae per parapodium. This new species, previously confused with S. albini (Langerhans, 1881), is the only currently known species of Synelmis from the New Zealand-Australia region. A neotype is designated for S. albini, a widely reported species of the tropics and subtropics, in order to clarify its taxonomic status.
Annelida, Polychaeta, Pilargidae, Synelmis, neotype, New Zealand, Canary Islands, new species.