Five new species and one new genus of the obscure spioniform family Uncispionidae are described together with three new species of the rare and unusual spionid genus Pygospiopsis Blake, 1983. All species are from offshore habitats with most from deep-sea continental slope depths. Among the Uncispionidae are the second and third species of the genus Uncopherusa Fauchald & Hancock, 1981, collected from off Brunei in the South China Sea and off Louisiana in the Gulf of Mexico; two new species of Uncispio Green, 1982, the third and fourth to be described, from deep water off the U.S. Atlantic coast and the Gulf of Mexico; and a new species of a new genus, Rhamphispio n. gen., from off the U.S. Atlantic coast. All species of Uncispionidae are compared and a key to the known species is presented. The genus Pygospiopsis Blake, 1983, is currently known for only two species: P. dubia (Monro, 1930) from Antarctic and sub-Antarctic waters and P. occipitalis Blake, 1996, from shelf depths off southern California. In the present study, new collections of the type-species P. dubia from the Antarctic Peninsula include post-larvae and juveniles as well as adults, thus permitting documentation of the development of some key adult morphology. Three new species of Pygospiopsis are described from deep water off the U.S. Atlantic and Pacific coasts and from the Antarctic Peninsula. A review of all species of Pygospiopsis suggests that, based on branchial distribution patterns, the closely related Pseudatherospio fauchaldi Lovell, 1994, should be referred to Pygospiopsis, bringing the total known species to six. All of these are compared and contrasted and the generic definition of Pygospiopsis updated. The status of Pygospiopsis within the Spionidae relative to the closely related genus Atherospio Mackie & Duff, 1986, is discussed.
New species and records of Uncispionidae and Pygospiopsis (Polychaeta, Spionida) from deep water off the east and west coasts of North America, the Gulf of Mexico, the Antarctic Peninsula, and Southeast Asia
