Rapid breakdown of allochthonous and autochthonous plant material in a eutrophic river

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. This revised version was published online in August 2006 with corrections to the Cover Date.