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 Author Bruno Rossaro Author Carlotta Casalegno text Zootaxa 2001 2001-08-31 7 1 20 journal article http://doi.org/10.5281/zenodo.4618447 b8a70227-3f95-4b6c-bab0-423990ebbee0 1175­5326 4618447 B8D6DBE1-9599-4328-A653-6B10532F5C48 Orthocladius marchettii Rossaro & Prato, 1991 O . marchettii Rossaro & Prato, 1991 DESCRIPTION. See Rossaro & Prato ( 1991 , Fig. 14, 15 ) . Often posterior segments V­VIII very dark and anterior segments light, but dark and light segments can be disposed in a variable pattern. In the same population, some pupal exuviae are observed with all abdominal segments light, except an anterior dark band; these specimens have no diagnostic characters to separate them from O . glabripennis . Frontal warts present, but not developed. Thoracic horn 450­480 m long with points on the whole surface, rounded and gently curved at apex. Thorax moderately rough. Pedes spurii B normally developed. Tergites with points all about the same size, on TIII posterior points more developed than the median ones (Fig. 1.1). On TIV­VI median points larger in the middle of tergite, grading in size from middle tergite outwards, particularly in TV . Posterior points on TIII­V extending laterally as far as the apical point band. Field of points on T III­VI extended antero­laterally well beyond anterior muscle marks and grading in size, antero­laterally extended points very small. Abdominal segment VIII with 4 / 5 lateral setae, the first and the last one often bifid, 3 or 4 lateral setae on segment VII , 3 on segments III­VI . Pedes spurii A present on S IV­VII . Anal lobes always without any taeniate extension of cuticle (Fig. 2.5). Anal macrosetae 250­280 m long, hooked at tips, anal lobes 400­475 m long and 510­555 m wide. 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 COMMENTS. This species has no taeniate extension of cuticle at the tips of anal lobes and resembles O . glabripennis and O . maius in this respect. The Nearctic species O . nigritus Malloch, 1915 is also described without spurs ( Soponis 1977 ) on anal lobes. O . marchetti is characterized by the dark pigmentation on abdominal segments. Nonpigmented specimens cannot apparently be separated from O . glabripennis . The species is known to occur only in Italian Apennines, but absent in Central Europe, Italian Alps and Padania lowland (Northern Italy ). The species is restricted to running waters. MATERIAL EXAMINED: ITALY : EMILIA ROMAGNA: Chiavenna stream, tributary of Po river (PC), 10 / 4 / 1979 , 1 Pex; 8 / 2 / 1980 , 1 Pex; Tributary of Taro river, Bedonia, 15 / 5 / 2001 , 1 Pex; Taro river, Compiano, 2 / 5 / 2001 , 1 Pex; Borgo Val di Taro, 2 / 5 / 2001 , 1 Pex; Bidente stream, 27 / 3 / 1979 , 1 Pex; Magra stream, 5 / 3 / 1981 , 1 Pex. ABRUZZO: Tordino stream, valle Teramo, 10 / 1 / 1990 , 1 Pex; Aterno river, 26 / 2 / 1990 , 1 Pex; 11 / 12 / 1991 , 1 Pex; 2 / 3 / 1992 , 1 Pex; 11 / 3 / 1992 , 1 Pex; Vetoio spring, 19 / 3 / 1992 , 1 Pex.