First record of the genus Kuwaita (Annelida: Lumbrineridae) in Europe with the description of a new species and new ultramorphological data for the genus.

A new species of the genus Kuwaita Mohammad, 1973, collected intertidally from a northern Spain estuary (Bay of Biscay), is described. Kuwaita hanneloreae sp. nov. constitutes the first evidence of this genus in European waters and is characterised by: prostomium with three small antennae protruding from nuchal fold, lack of eyes; simple multidentate hooded hooks with long hood in anterior chaetigers, and short hood in posterior ones with well defined proximal and distal teeth with several teeth between them; posterior chaetigers with very small nephridial papillae; branchiae reduced to little knobs in posterior parapodia; maxillary apparatus with five pairs of maxillae, MIII bidentate with distal tooth bigger than proximal one. We present brief notes on its ecology and remarks on the presence and ultrastructure of a notopodial sense organ newly recorded for the genus. Furthermore, an updated key of the genus Kuwaita is included.