Orthocladius oblidens (Walker, 1856)

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 : 8-9

Orthocladius oblidens (Walker, 1856)

O. oblidens (Walker, 1856)

O. lenzi Kieffer, 1924 ( Langton & Cranston 1991)

Orthocladius sp A Pinder, 1978 ( Langton, 1991: 184; Langton & Cranston 1991)

Orthocladius Pe 2 Langton, 1984: 150 ( Langton & Cranston 1991)

nec Chironomus oblidens Walker, 1856 , sensu Langton, 1984: 154 ( Langton & Cranston 1991) O. pinderi Rossaro & Prato, 1991 Syn. n.

DESCRIPTION. See Langton & Cranston (1991, Fig. 1 h, 2f, 4h) and Rossaro & Prato (1991, Fig. 20, 21, 22, sub O. pinderi ). Thoracic horn 335­470 m long. Hook row on TII not very extended (135­200 m wide). Pedes spurii B well developed. TII only with small points present on the posterior field. Points on TIII­VI with posterior points about the same size or larger than median points. TIII with the anterior and lateral part of tergite devoid of points. The posterior point band of TIII­IV extending further laterally than the apical band. T IV­VI leaving an antero­median bare area with points extending to the antero­lateral corner, diminishing in size; the median points somewhat larger than the more lateral, showing as a more or less circular area within the point patch. Frequently setae on S II­III branched. Pedes spurii A present on S IV­VII. Only very weak points present on T VII and on SVI at caudal margin. Lateral setae very short and weak. Robust taeniate extensions at the tip of anal lobes present. Apical setae of anal lobes not hooked at tips and short (95­150 m long), less than half the lobe length (350­450 m), anal lobes 315­375 m wide.

COMMENTS. The adult male was described and figured by Pinder (1978, p. 72, Fig. 113 A) and labelled Orthocladius sp. a. The pupal exuviae was described by Langton (1984: 150) and labelled Orthocladius Pe 2. Pinder (1978) stated that it resembled the species figured and determined by Brundin (1947) as O. oblidens (Walker, 1853) . The examination of Walker's holotype ( Pinder 1978) suggested that it was different from the species figured by Brundin (1947), so O. oblidens (Walker) sensu Brundin was designated by Pinder (1978) as a different species (= Orthocladius sp. a), but it was not given a name. Rossaro & Prato (1991) reared pupae and obtained pupal exuviae identical to the ones described by Langton (1984, 1991) and adult males identical to the ones figured by Brundin (1947) and Pinder (1978). This lead Rossaro & Prato (1991) to give a name to Orthocladius sp. a Pinder, O. pinderi . Langton & Cranston (1991) emphasised that the differences in male hypopygia between O. oblidens and Orthocladius sp a Pinder were untenable; the latter was stated as a junior synonym of the former; the synomymy between O. pinderi and O. oblidens is here confirmed as a consequence.

MATERIAL EXAMINED: ITALY: PIEMONTE: Po river, Pontestura, 13/12//1983, 1 Pex; Trino Vercellese, 10/11/1967, 1 Pex. LOMBARDIA: Po river, Pieve Porto Morone, 3/5/1980, 1 Pex; 29/5/1980, 1 Pex; Bardello stream, 15/5/1979, 1 Pex; Endine lake, st. G4, 25 /2/1981, 1 Pex; Serio river, Ricengo, 24/5/1999, 1 Pex; 28/6/1999, 1 Pex; 27/9/ 1999, 1 Pex; 23/1/2000, 1 Pex; 18/2/2000, 1 Pex; 23/3/2000, 1 Pex; 15/4/2000, 1 Pex; Lambro river, Asso, 16/11/1977, 1 Pex; a pond near Cesano Maderno, Milano, 3/2001, 1 Pex; Ticino river, Castelletto di Cuggiono, 26/3/2001, 1 Pex. EMILIA ROMAGNA: Aveto lake 1/5/1986, 1 Pex; Po river, Corso, 12/1975, 1 Pex; 5/1977, 1 Pex; 21/11/1978, 1 Pex; 2/7/1979, 1 Pex; Isola.Serafini, 18/12/1980, 1 male /Pex/Lex; Adda river, Porto d'Adda, 13/12/1983, 1 Pex. Tributary of Taro river, Bedonia, 15/5/2001, 1 Pex. MARCHE: Potenza river, st, 2, S.Severino, 8/4/1986, 1 Pex. LAZIO: Velino river, Antrodoco 11/3/1990, 1 Pex; 17/3/1990, 1 Pex; 17/3/1990, 1 Pex. ABRUZZO: Aterno river, Coppito, 9/3/1992, 1 Pex; a spring loc. Ovindoli, Fucino, 6/5/1989, 1 Pex; Vetoio spring, 19/3/1992, 1 Pex; 13/ 5/1992, 1 Pex; 27/5/1992, 1 Pex; Zittola stream, 26/5/1992, 1 Pex.

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