Leuctra biellensis Festa, 1942

Vincon, Gilles, Boumans, Louis & Gattolliat, Jean-Luc, 2018, Reinstatement of Leuctrabiellensis Festa, 1942 (Plecoptera, Leuctridae), Alpine Entomology 2, pp. 35-43 : 36-39

Leuctra biellensis Festa, 1942 Figs 1, 3 a–g, 4

Leuctra biellensis , Consiglio 1962

Leuctra nigra Oliv., Fochetti and Tierno de Figueroa 2008: 259, fig. 160 a–f.

Locus typicus : Alpe Finestre, Val Chiobbia, Piemonte (altitude 1700 m).

Material examined.

Neotype (GBIFCH00235761): Italy, Pennine Alps: Biellese mountains, Oropa, torrents and brooks, 1200-1900 m, 06.1978-07.1978, Coll. C. Ravizza, 1♂ (Museo Civico di Storia Naturale "Giacomo Doria", Genova, Italy).

Topotypes (GBIFCH00235762): same data as neotype: 175♂, 153♀.

ITALY: Pennine Alps: Civiasco, (NO), 700 m, 25.04.1992, 16♂, 2♀; Valsesia, Morce brook, 500 m, 25.04.1975, 5♂, 1♀ (Rav); Biellese mountains, brooks, Elvo trib., 1100 m, 18.05.1981, 7♂, 1♀(Rav); Biellese mountains, Donato, Vione tor., 950 m, 21.05.1979, 16 larves (1 male nymph) (Rav); Andrate, Graglia, slow brook, Mombarone mount, 5.06.1978, ♂, ♀ (Rav). Aosta Valley, Dora Baltea trib.,> Trovinasse, Colla della Lace, 1900 m, 11.07.2003, 1♂;> Trovinasse, Colla della Lace, 1700 m, 24.05.2003, 4♂, 6♀; Dora Baltea trib., Pont-St-Martin,> Carema, 500 m, 1.06.1991, 2♂, 4♀; Dora Baltea trib.,> Nomaglio, road from Andrate to Biella, 600 m, 1.06.1991, 13♂, 9♀; 31.03.2000, 1♂, 1♀; E. Varallo, Civiasco, Sesia trib., b., 850 m, 2.06.1991, 2♂, 1♀; N. Varallo,> Cervarolo, 1500 m, 2.06.1991, 4♂, 1♀; <Cervarolo,> Piane del Alpe, b., 1200 m, 2.06.1991, 9♂, 6♀; W. Grevellona, Val Strona,> Campello Monti, 1500 m, 13.08.2005, 1♀; Val Strona,> Massiola, <Rosarolo, b., 750 m, 26.04.1999, 12♂, 3♀; Val Strona,> Omegna, b., 500 m, 24.05.2003, 2♂, 1♀; SW. Domodossola, Valle Anzasca, Macugnaga, Staffa, b., 1300 m, 2.06.1991, 16♂, 16♀; Valle Anzasca, Macugnaga, Prequartera, 800 m, 1.06.1991, 3♂, 3♀ (Vin). Cottian Alps: Ceres, Almesio, 750 m, 11.06.2001, 4♂, 3♀; Lemie, Val d’Ovarda, A. Milone, 1650 m, 20.06.2001, 1♂, 4♀; Locana, val Piantonetto, S. Giacomo, 1130 m, 26.06.2001, 1♀; Villafranca Piemonte, TO, Cappella della Missione, 260 m, 24.03.2002, 2♂; (Del); Graian Alps: Frassinato brook, Soana trib., 1000 m, 18.06.1992, 1♀ (Rav); Val Soana, 700 - 850 m, 11♂, 6♀ (Rav); Lis Pass,> Girardi, Stura di Lanza trib., b., 1100 m, 7.05.2000, 5♂, 2♀; 27.08.2005, 2♀; Val di Viu, Stura di Lanza trib.,> Viu, Piazette, b., 1200 m, 1.04.2000, 3♂; Val di Viu, Stura di Lanza trib., <Viu, brook, 600 m, 22.04.2008, 3♂, 6♀; NE. Lanzo Torinese,> Corio, Pian d’Audi, Rio Malone trib., 865 m, 23.10.2000, 1♀; Aosta Valley,> Quincinetto,> Scalaro, 1500 m, 1.05.2009, 1♀;> Quincinetto, Rio della Folla, 1250 m, 11.07.2012, 1♀;> Quincinetto, road to Lecchia sup. and road to Scalaro (iron bridge), 1100 m, 1.05.2009, 1♂; Aosta Valley,> Champorcher, Valle della Legne, Ayasse trib., 1200 m, 6.05.2000, 1♂ (Vin). Rhaetian Alps: Po Valley, Rocchellaif, Po, 550 m, 1.05.1982, 4♂, 1♀ (Rav). Liguria: Calizzano brook, 900 m, 28.04.1976, 3♂ (Rav); (SV) Calizzano, Melogno Pass, Frassino trib. 800-1000 m, 27♂, 4♀ (Rav); Montenotte, Erro spring, 700-950 m, 4.05.1974, 48♂, 40♀ + 65♂, 58♀ (Rav); Mont San Giorgio, brook, 750 m, 16.04.1974, 10♂, 3♀ (Rav). Lombardia, Casargo, (CO), Varonne tor., 2.06.1973, 21♂, 16♀, Bucuarelli leg (Rav); PreAlps, San Michele (VA), Olocrene spring, 800 m, 8.07.1986, 2♂, 3♀(Rav).

SWITZERLAND: Ticino, Lepontine Alps: Ceneri Mount,> Isone, before the military base, 1.04.2015, 10♂, 5♀ (Vin); Valle Lucoresagguo, Piace Seguo, 1650 m, 23.05.1988, 28♂, 16♀ (Rav). Rhaetian Alps: Graubünden, Cavagliasch, Cavaglia, 1690 m, 30.05.2007, 2♂ (P. Baumann).

Complementary description.

Male (Fig. 3 a–f): Tergite VI with two small triangular appendices pointing upwards and backwards in side view (Fig. 3b). Tergite VII with non-interrupted anterior margin and wide median bell-shaped membranous area. Tergite VIII with two strong teeth pointing upwards and backwards (Fig. 3a, b) and nearly triangular in dorsal view (Fig. 3f). Tergite IX with anterior margin interrupted on nearly one third of segment width, lateral edges sub-triangular forming a wide strip along anterior margin (Fig. 3a). Lateral lobes of paraprocts with a sclerotized sickle-shaped expansion slightly bent towards distal part of specilla (Fig. 3 c–d). Specilla straight in ventral and side views (Fig. 3 c–d). Sternite IX: ventral vesicle racket-shaped (Fig. 3e). Female (Fig. 3g): subgenital plate with two rounded lobes separated by a small triangular lamella; a triangular sclerite placed between the 2 lobes is visible by transparency under the cuticle.

Ecological preferences and distribution area.

Leuctra biellensis is a crenophilic species occurring in springs and brooklets at various altitudes (260-1900 m). The flight period is mainly in spring and early summer ( III–VII) but few adults also occur in autumn ( VIII–X). Its distribution area widely covers the western part of the Italian Alps from the Rhaetian Alps to the Maritime Alps and also extends in Liguria (Fig. 4). Its occurrence in Switzerland is restricted to the southern slope of the Alps.