Reinstatement of Leuctra biellensis Festa, 1942 (Plecoptera, Leuctridae)

Both molecular and morphologic characters support the reinstatement ofLeuctrabiellensisFesta, 1942 as a valid species distinct fromLeuctranigra(Olivier, 1811). Genetic distances betweenL.biellensisand the different populations ofL.nigraare around 9%, while intraspecific distances amongL.nigrahaploclades are less than 1%. Morphologically, the two species can be separated in male adult specimens by the shape of the two teeth on tergite VIII, by the lateral edges of tergites and by the distal expansion of the paraprocts.Leuctrabiellensisoccurs on the southern slope of the Alps in Italy and Switzerland (Ticino and Graubünden), whileL.nigrahas a wide distribution in Central and Northern Europe. As the type material ofL.biellensiswas lost, and to avoid future confusion between the two species, we designate as neotype a male imago collected at the type locality.