196 U. S. NATIONAL MUSEUM BULLETIN 216 



than the Polysphinctini. The ovipositor is like that of no other 

 ichneumonid. In its shortness and its long tapered point it is like 

 the Polysphinctini, but its surface is mat rather than polished and 

 the submedian swelling present in the Polysphinctini is lacking in 

 Clistopyga. The female subgenital plate is large and scoop-shaped, 

 and thus is like no other genus of its subfamily. A minor character, 

 but one of interest, is that in some species of Clistopyga the apex of 

 the hind tarsus is paler than the preapical part, a color pattern that 

 often occurs in the genera Zaglyptus and Tromatobia. This color 

 character shows up sometimes also in the primitive Polysphinctini. 



The adult morphology gives conflicting evidence, and for more indi- 

 cations of its true relationships, we turn to the early stages and biol- 

 ogy. Here too the evidence is conflicting, but though the genus has 

 been reported as parasitic on a diverse assemblage of hosts, it seems 

 very probable that the true hosts are spiders or their egg sacs, and 

 that records of other hosts are due to overlooking parasitized spiders or 

 their eggs among the other material from which rearings were made. 



Nielsen has published the most circumstantial account of the biol- 

 ogy of Clistopyga (1929, Entomologiske Meddelelser, vol. 16, pp. 

 366-368). He reared Clistopyga incitator in Germany as a gregarious 

 parasite in an egg sac of Sergestria senoculata. The larval and pupal 

 morphology, as he figures them, are very similar to those of Troma- 

 tobia and Zaglyptus, and different from those of the Polysphinctini. 

 With these data and a consideration of additional evidence, which 

 is admittedly fragmentary and inconclusive, it appears that Clistopyga 

 is parasitic in the egg sacs of those spiders whose egg sacs are placed 

 in various kinds of crevices, and that the genus is rather closely 

 related to Tromatobia and Zaglyptus, in the Pimplini. 



Key to the Nearctic species of Clistopyga 



1. Frontal orbit white or partly white; temple weakly convex, in profile as long 



as eye 2 



Frontal orbit not white but usually a white orbital mark at top of eye; temple 

 moderately convex, in profile 0.6 to 0.7 as long as eye 4 



2. Submetapleural carina complete; range: eastern North America. 



7. recurva (Say) 



Submetapleural carina present only on front third of metapleurum; range: 



western North America 3 



3. Hind tibia without a subbasal brown band; white orbital mark on frons 



interrupted just above antennal socket; propodeum exceptionally short ana 



flat 5. nigrifrons Cushman 



Hind tibia with a subbasal brown band; white orbital mark on frons not 

 interrupted; propodeum moderately long, rather strongly convex. 



6. manni Cushman 



4. Abdomen largely fulvous; hind tibia fulvous with an apical and subbasal 



infuscation; mesopleurum and metapleurum rather strongly mat. 



4. alutaria, new species 



