ICHNEUMON-FLIES — GELINAE I MESOSTENINI 399 



0.4 abruptly declivous, its apical margin truncate or weakly convex, 

 without a median point; mesoscutum moderately convex, mat, and 

 with moderately dense to sparse medium-sized punctures; notaulus 

 sharp, reaching beyond center of mesoscutum; epomia strong, the 

 upper edge of pronotum with a blunt tubercle at its upper end; pro- 

 podeum with distinct dorsal and posterodorsal faces, with more or 

 less distinct longitudinal carinae as well as the two transverse carinae, 

 its transverse carinae both strong and complete, the apical transverse 

 carina with strong sublateral crests; propodeal spiracle circular; 

 areolet very small, subquadrate, the second intercubital absent or 

 vestigial ;ramellus absent; nervulus opposite or a little basad of basal 

 vein; second discoidal cell moderately narrowed basally; mediella 

 strongly arched; nervellus broken below the middle; axillus close to 

 anal margin; first abdominal segment rather short, broad, without a 

 subbasal lateral tooth, its ventrolateral carina complete and moder- 

 ately sharp, its dorsolateral carina blunt but complete, its median 

 dorsal carinae absent or weak, if present reaching to a little beyond 

 spiracle; spiracle of fh-st tergite near its apical 0.40; second tergite 

 mat, with fine v/eak punctures that are separated by more than the 

 length of the hairs; tergite 7 without a median white spot but often 

 margined with white or almost entirely white; ovipositor sheath about 

 0.12 as long as front wing; ovipositor moderately slender, its tip 

 somewhat sagittate. 



Pachysomoides is a small genus, Neotropic in distribution except 

 that two species range northward into the Nearctic region. So far 

 as known, it is parasitic only in the nests of Polistes. 



Key to the Nearctic species of Pachysomoides 



1. Body black and white; punctures on mesoscutum sparse, separated by about 



1.5 their diameter 1. stupidus (Cresson) 



Body fulvous with inconspicuous whitish and fuscous areas; punctures on 

 mesoscutum dense, separated by about 0.4 their diameter. 



2. fulvus (Cresson) 



1. Pachysomoides stupidus (Cresson), new combination 



Figure 334,b 



Mesostenus stupidus Cresson, 1873, Proc. Acad. Nat. Sci. Philadelphia, vol. 25, 



p. 159; 9. Tj'pe: 9, Orizaba, Mexico (Philadelphia). 

 Pachysoma albopictum Szepligeti, 1916, Ann. Mus. Nat. Hungarici, vol. 14, p. 



290; 9. New synonymy. Type: 9 , Mexico (Budapest). 

 Polistiphaga zonata Cushman, 1929, Proc. U.S. Nat. Mus., vol. 74, art. 16, pp. 



4, 56; 9. Type: 9, Victoria, Tex. (Washington). 



Front wing 3.4 to 6.3 mm. long; punctures on mesoscutum weak, 

 separated by about 1.5 their diameter; punctures on mesopleurum so 

 fine and weak as to be difficult to see; basal and apical carinae of 

 propodeum farther apart than in P. juLvus. 



