Onesia. 



157 



3. O. biseta Villen. in litt. Kram. 



1917. Kram. Abhandl. Nat. Gesell. Gorlitz 28, 292. — 1924. Stein, Arch. 

 f. Naturgesch. 90, 6, 266, 2. — CallipJiora scpulchralis 1896. Pand. (nec Meig.) 

 Eev. Entom. XV, 209, 2. ^ 1902. Villen. Wien. Ent. Zeitg. XXI, 26, Fig. 2 

 et 4. ^ 1911. Kram. 1. c. 27, 43, Tab. III, Fig. 13. 



Male. Tilis species is in all respects similar to aculeata, differing 

 only in the genitalia. Palpi yellow to black. Upper forceps cleft to 

 middle, the branches close-lying, curved a little ventrally; the arms 

 of lower forceps are broad and with a 

 little dilatation at base, they are curved 

 and somewhat obliquely cut at apex; 

 on the inner side they have a depression 

 at base and on the outer side a furrow; 

 they are somewhat converging at apex. 

 Front tibiæ with two posterior bristles 

 or often with only one. 



Female. The female I cannot distin- 

 guish from aculeata, unless specimens 

 with two bristles on front tibiæ. 



Length 5,5 — 9 mm. 



O. biseta seems to be more common 

 in Denmark than aculeata; Ordrup Mose, 

 Ermelund, Dyrehaven, Lyngby Mose, 

 Birkerød, Grib Skov, Tisvilde; on Lol- 

 land at Nysted; on Funen at Veflinge and in Jutland at Kliplev, 

 Skanderborg and Skagen and on Læsø; the dates are ^^/g — ^^s- I 

 have bred it from a pupa taken in the ground on ^/g, the imago 

 appearing next day. 



Geographical distribution : — Europe down into France ; hitherto 

 not known north of Denmark. 



Remarks: Villeneuve gives as character two posterior bristles 

 on front tibiæ; Stein says that there is often only one, and thinks 

 it possible that these specimens may be a distinct species as the 

 arms of lower forceps seem to him more slender and longer. All my 

 male specimens have only one bristle on front tibiæ except five spec- 

 imens, all from Veflinge, but whether they are specific distinct from 

 biseta I dåre not say, but I do not think it probable; one of the spec- 

 imens was also determined by Villeneuve as biseta (perhaps agilis 

 Meig. might be hidden among them). Of my females a couple shows 

 two bristles. 



Fig. 33. O. biseta, forceps in 

 profile. 



