PTEROMALIDAE OF N.W. EUROPE 805 



of boucheanus, since Ratzeburg's description suggests that the two are in fact 

 identical. 



The taxonomy of the European species of Dibrachys is not yet completely cleared 

 up. At least five species occur in Britain, and I have seen about as many additional 

 species from the Continent. The morphological characters separating some of the 

 presumed species are rather small, whilst on the other hand the biology of some is 

 not known so that evidence is not forthcoming from this aspect. Some species 

 have been recorded from only one or two hosts, while on the other hand cavus 

 (Walker) in the sense of recent authors (e.g., Peck, 1963) has an enormous list of 

 hosts. Perhaps cavus is in fact very polyphagous, but I would not rule out the 

 possibility that it (in the current sense) may include two or more sibling species. 

 Only an extensive assessment of morphological characters combined with careful 

 biological observations can settle this question. Until recently no key to the 

 European species of Dibrachys existed ; that of Boucek (1965^) has, however, 

 clarified their relationships. My own key was produced independently, but to 

 some extent employs characters also used by Boucek. 



Key to most European Species 



(Males and Females) 



1 Vertex curving very strongly in the longitudinal axis, the occipital carina very 



close to the foramen magnum. Left mandible with 3 teeth, right mandible 

 with 4. 



Body squat. Gaster of female only 1-1-1-4 times as long as broad, not or 

 only slightly longer than the thorax, only bluntly pointed apically. (Sgen. 

 Allodibrachys Boucek) .......... 2 



- Vertex curving less strongly in the longitudinal axis, the occipital carina at most 



slightly nearer to the foramen magnum than to the posterior ocelli. Both 

 mandibles with 4 teeth. 



Body sometimes more slender. Gaster of female 1-6-2-6 times as long as 

 broad, usually longer than the thorax, often acute apically. (Dibrachys 

 Forster, s. str.) ........... 3 



2 (1) Genae, in frontal view of head, almost straight, forming a distinct angle with the 



oral edge of the head. POL about i-8 OOL. Marginal vein of fore wing 

 2-2*1 times as long as the stigmal vein. Larger species, length 2-2-5 mm. 



hians Boucek (p. 808) 

 Genae in frontal view evenly curved, not forming a distinct angle where they 

 meet the oral edge of the head. POL approximately twice OOL. Marginal 

 vein 1-75-1-9 times as long as the stigmal vein. Smaller species, length 

 16-2 mm. 

 Clypeus, Text-fig. 658 ....... affinis Masi (p. 808) 



3 (1) Face below antennal toruli fiat, finely wrinkled transversely. Fore wing strongly 



and extensively infumate discally. Large species, 2-9-3-8 mm. 



maculipennis Szelenyi (p. 814) 

 Face below antennal toruli convex, reticulate. Fore wing usually hyaline or 

 with a small infumate discal cloud, rarely with a large one. Species some- 

 times relatively smaller .......... 4 



4 (3) Anterior margin of clypeus (Text-fig. 660) more deeply emarginate, with a long 



and deep median impression above the emargination. Breadth of oral fossa 

 2-8-3 times the malar space. Antennal flagellum of female stout ; second 



