BR. I I. NT NAT HIST., I.V 2001 



The two British Symnwrus species can be separated as follows. The knob of the 

 haltercs is black and the legs yellow in both species: 



Males 



Thorax yellowish except for three fused shining dark brown stripes on 

 mesoscutum, the middle stripe extending to the fore margin. Abdomen with tergites 

 black, sternites 1-4 yellow, rest and genitalia brown. Head dark brown; antenna with 

 scape and pedicel yellow but ilagellum all black. Wing length 6.0-6.1 mm 



nobilis Lackschewitz 



Thorax more uniformly yellowish brown with two vague broad brown lateral 

 stripes near wing base and median stripe absent. Abdomen with yellow basal bands 

 on tergites 2-7, sternites all yellow. Antenna with basal part of flagellum also yellow. 

 Wing length 6. 2-7. 3mm. annulatus (Meigen) 



Females 



Thorax entirely shining black on mesoscutum, pleura and mediotergite brownish 

 yellow. Abdomen entirely shining dark brown and ovipositor brown. Antenna as 

 male, scape and pedicel more brownish yellow. Wing length 7.1mm (1 Swiss 

 specimen). nobilis Lackschewitz 



Thorax as male, but usually with shining median stripe to fore margin (reddish 

 brown or sometimes darker; occasionally stripes fused with only humeral area pale) 

 and with dark marking on lower part of laterotergite and mediotergite. Abdomen 

 dark brown to segment 7, but ovipositor paler, more yellowish. Antenna as male, 

 with flagellum yellow to flagellomeres 5-6 (or less in darker specimens). Wing length 

 5.1-6.3 mm. annulatus (Meigen) 



British material of S. nobilis: 



SCOTLAND: Inverness-shire, Glen Coiltie, around piles of fallen branches by 

 River Coiltie in mixed deciduous woodland, 3 males: 21.vii., 23.vii and 24.vii.1997 

 (Chandler, 1 male in NMS). 



Keroplatidae 



Orfelia bicolor (Macquart) (Figs 6-8) 



This species was recorded as British by Chandler (1992a), who figured the 

 ovipositor, based on a single female from Magor Marsh. Gwent in Wales. One male 

 has now been found in Britain, from which the genitalia are figured (Figs 6-8). This 

 was obtained from a forested site, which is more typical of the habitats in which 

 O. bicolor has been recorded in Europe. 



As in the case of the female, it does not fit either of the alternatives in couplet 1 of 

 the key to the genus by Hutson et al. (1980), since the thorax is dark dorsallv while 

 the pleura, a narrow humeral area and the apical margin of the seutellum are 

 yellowish; the mediotergite is darker yellowish. The abdominal tergites 2-4 and 6 are 

 yellow on the apical half (or more on tergite 2), tergite 5 is dark and the genitalia are 

 brown. The gonostylus is single in common only with nemoralis (Meigen) and pallida 

 (Staeger) among British Orfelia species, but differs from them in its simple narrow 

 and apically flattened form. Wing length of this specimen 3.2 mm. 



British male material of O. bicolor: 



ENGLAND: Bucks, Burnham Beeches, Malaise trap. 20.vii-2.viii.1995. 1 male (J.W. 



Ismay; in author's collection). 



