A new species of
Uncispio Green, 1982 is described from a boulder clay habitat in the southern Irish Sea.
Uncispio reesi n. sp. can be separated from
Uncispio hartmanae Green, 1982 by the size and shape of the occipital antenna, the arrangement of the posterior parapodial lobes, the number of anal lobes and the position and shape of thickened anterior neuropodial chaetae. The other two species of Uncispionidae,
Uncispio hartmanae and
Uncopherusa bifida, are re-examined and their descriptions expanded. The family status of Uncispionidae is discussed with respect to the other families in Spionida. [Proceedings of the 10th International Polychaete Conference (20-26 June 2010, Lecce, Italy) ]