Orthocladius frigidus (Zetterstedt, 1838)

Bruno Rossaro & Carlotta Casalegno, 2001, Description of the pupal exuviae of some species belonging to Orthocladius s. str. van der Wulp, 1874 (Diptera: Chironomidae: Orthocladiinae), with a new key to species of West Palaearctic region, Zootaxa 7, pp. 1-20 : 5

Orthocladius frigidus (Zetterstedt, 1838)

DESCRIPTION. Thienemann (1944: 597), Soponis (1977) and Langton & Cranston (1991, Fig. 1 g, 4g) gave descriptions of this species. Well marked anterior and lateral dark band on abdominal segments. Posterior segments darker. Thorax wrinkled, not rough. Thoracic horn very long and slender, about ten times long as large, with the basal part chitinised and the distal part transparent, easily damaged in collected specimens. Pedes spurii B present on segment II, but not well developed. Points of T II reduced to a well developed posterior field, median field absent or present. Posterior field of points stronger than anterior and median fields on T III­VI, where only a narrow anterior and lateral field is generally free of points. Points on apical fields strong on T III­V. In some specimens points are very extended on T II ­III. Points present on S II­III­VI­VII­VIII, particularly extended on SVII. Pedes spurii A on S IV­VI. Anal lobes convex externally, narrow in the distal part, without taeniate extensions of cuticle at tips. Three lateral setae on segments II­VII, four­five on segment VIII. Anal macrosetae 195­220 m long, anal lobes 320­440 m long and 375­ 500 m wide.

REMARKS. There are specimens with more extended points, especially on T II­III. These specimens appear quite similar to O. vaillanti , but lack the fringe of setae on anal lobes.

MATERIAL EXAMINED: ITALY: PIEMONTE: Acqualba stream, 5/1976, 1 male pupa. LOMBARDIA: Varese lake, Gallavesa stream, 12/11/1977, 1 male pupa; Lambro river, 10/2/1977, 1 Pex; 16/11/1977, 1 Pex; 22/12/1995, 1 Pex; Oglio river, 4/1978, 1 male/Pex/Lex; 25/3/1978, 1 Pex; 16/8/1978, 1 Pex; 24/8/1978, 1 male pupa /Lex; Passo dello Stelvio, 14/8/1977, 1 Pex. TRENTINO: Ortles glacier, 14/8/1977, 1 Pex; Coredo lake, 7/7/1996, 1 male pupa; spring near Sella pass, Dolomiti, 6/8/1988, 1 Pex. EMILIA ROMAGNA: Bidente stream, 27/3/1979, 1 Pex; a creek near Cisa pass, 6/3/1981, 1 female /Pex. MARCHE: Aso stream, 17/4/1980, 1 Pex. ABRUZZO: Parco Nazionale Abruzzo (PNA), 20/5/1978, 1 male pupa; Vera spring, 24/3/1988, 1 female /Pex/Lex.

Figures

FIGURE 1. Ventral view (sternite) on the left, dorsal view (tergite) on the right. 1.1: O. marchettii: tergite III with anterior, median, posterior and apical point fields; 1.2: O. pedestris: tergite III with anterior, median, posterior and apical point fields