Pseudectinosoma reductum, a new ectinosomatid harpacticoid from spring waters in Italy (Crustacea: Copepoda)

A few specimens of Pseudectinosoma reductum sp.n. were collected from a crenal biotope of the Presciano spring system (Tirino River, Aterno-Pescara Basin) in central Italy, at an altitude of 330 m a.s.l. This remarkable new species is easily distinguishable from all congeners in the unique shape of the fifth leg, which lacks any trace of armature. This character state as well as the reduced armature of legs 1-4 and the 4-segmented antennule may be considered evolutionary novelties within the genus. Ecological information is given for the species.