Historic species records of the families Onuphidae and Eunicidae, from the Falkland Islands region, are reviewed and updated, new records added from intertidal and nearshore localities on and around the Falkland Islands, and a new species of Hyalinoecia described. Eight genera are reported from around the region including eight taxa of Onuphidae and two of Eunicidae, although most are only known from deep offshore waters. Kinbergonuphis dorsalis is re-described from type material, Kinbergonuphis sp. from the Falkland Islands is described and discrepancies between the two descriptions are examined. Hyalinoecia falklandica sp. nov. is described and the history of the genus and its misidentification in the region is discussed. The new species is distinguished from all other species in the genus through a combination of simple, unidentate falcigers on chaetigers 1 and 2, ventral cirri present to chaetigers 3 or 4, and branchiae present from chaetigers 26 or 27 to the end of the body. The historic record of Marphysa aenea from the Falkland Islands is also shown to be a misidentification and the actual, as-yet-undetermined species present is described. Problems surrounding a correct identification of Marphysa species, other species that do not quite fit current descriptions, and additional Eunicoidea taxa that might be expected to occur in the region are also discussed.

Deep-sea ecosystems are generally oligotrophic because they lack photosynthesizing producers. On deep-sea slopes near land, however, various terrestrial plant remains flow to and are deposited on near-shore deep bottoms. From a depth of 300 m off the Pacific coast of Owase, central Japan, we collected an onuphid polychaete, Anchinothria cirrobranchiata (Annelida: Onuphidae), which lives in a dorsoventrally flattened portable tube. The polychaete tubes were made of sand, as well as leaves and twigs of terrestrial evergreen trees. The leaves glued on the portable tubes were chartaceous, blackish and tough; they belonged mainly to two genera of Fagaceae, Castanopsis and Quercus, which are dominant components of coastal evergreen oak forests. In aquaria, the polychaetes fed on the leaves on their tubes, as well as autochthonous sedimented leaves, suggesting utilization of terrigenous plant litter as food. As to the evolution of Anchinothria, a molecular phylogenetic analysis suggests that Anchinothria is monophyletic with other Hyalinoeciinae (Nothria, Leptoecia, Hyalinoecia).

Mooreonuphis bidentata, a new species of onuphid polychaete, is newly described from the Mexican Caribbean. It was found in dead coral rocks at depths of 2.2 m and can be distinguished from its congeners by having simple filaments branchiae from chaetigers 19–24, as well as bi- and tridentate pseudocompound falcigers and large median simple tridentate hooded hooks in the first four chaetigers. Including M. bidentata sp. nov., the genus Mooreonuphis includes 19 species, which have been exclusively collected on the American coasts, mainly in tropical and temperate waters. From the Caribbean Sea, six species have been recorded. Of these, M. bidentata sp. nov, M. cirrata, M. dangrigae and M. intermedia are the only species having their locus typicus in this tropical region. A taxonomic key is presented for all the species of Mooreonuphis recorded from both sides of the American seas.

A new species of Australonuphis Paxton, 1979 from the Ecuadorian coast, eastern Pacific, is described. The new species is characterized by seven modified parapodia, cirriform ventral cirri on the anterior 16 to 19 chaetigers, subacicular hooks beginning from chaetigers 43 to 57, and cirriform interramal processes on chaetigers 7–10 to 16–18 transformed back in a rounded lobe. This species belongs to the species group with unidentate pseudocompound hooks. Other species of this group are A. beltrani de León-González & Góngora-Garza, 1993, A. hartmanae (Friedrich, 1956), A. parateres Paxton, 1979 and A. teres (Ehlers, 1868).