514 U. S. NATIONAL MUSEUM BULLETIN 216 paet 3 



Chenbergus Navas, 1930, Bol. Soc. Ent. Espana, vol. 13, p. 43. New name for 

 Brachycentrus. 



Front wing 3.5 to 7.2 mm. long; clypeus small, short, its basal 

 0.6 ± very weakly convex, the apical 0.4 ± flat or very weakly con- 

 cave, tiie apical margin broadly truncate, with a small median tooth ; 

 sternaulus absent or faint; pleural carina present or absent; basal 

 carina of propodeum near midlength of propodeum, angled forward 

 toward midline to make a broad, inverted V; apical carina of propo- 

 deum present but rather weak in H. annulicornis, absent in all other 

 species; areolet very small, often open; nervulus distad of basal vein 

 by about 0.3 its length; nervellus broken below the middle; first 

 abdominal segment very short and stout, without a subbasal lateral 

 tooth, the median dorsal carinae very weak except in H. annulicornis; 

 spiracle of fu'st tergite a little in front of the middle; ovipositor 0.50 

 to 0.78 as long as front wing, the tip of upper valve enclosed by lower 

 valves not at all or only along its lower edge, the teeth on ovipositor tip 

 moderately distant. 



Helcostizus is a small genus. The distribution is Holarctic, There 

 are five Nearctic species, of which one occurs also in Eurasia as a 

 distinct subspecies. Specimens are rare in collections. The treat- 

 ment below suffers from lack of material, and must be considered 

 tentative. The species are parasitic on coleopterous borers in small 

 branches. 



Key to the Nearctic species of Helcostizus 



1. Propodeum with both basal and apical transverse carinae present, the apical 



carina either complete or interrupted medially; median longitudinal carinae 

 of first tergite moderately sharp on basal 0.6 ± and traceable to apex of the 

 tergite; basal tooth of ovipositor tip vertical . . 1. annulicornis (Walsh) 

 Propodeum with only the basal transverse carina (but this carina further 

 apicad than its usual position); median longitudinal carinae of first tergite 

 very blunt, usually not traceable beyond midlength of the tergite; basal 

 tooth of ovipositor tij? slanted at a 45° angle 2 



2. Hind tibia white, with an apical and a subbasal fuscous band ; propodeum about 



1.1 as long as wide 2. tibialis, new species 



Hind tibia medium brown to black, often with a basal whitish band; propodeum 

 about 0.75 to 0.95 as long as wide 3 



3. Upper half of mesopleurum polished or subpolished; ovipositor about 0.78 as 



long as front wing 3. subrectus, new species 



Upper half of mesopleurum rather strongly mat except that speculum (upper 

 hind part of mesopleurum) is polished 4 



4. Ninth tergite of female elongate, in dorsal view about 1.4 as long as wide; 



ovipositor about 0.74 as long as front wing. Male unknown. 



4. oxyura, new species 



Ninth tergite of female of normal length, in dorsal view about 0.9 as long as 



wide; ovipositor about 0.57 as long as front wing . 5. albator (Thunberg) 



