ICHNEUMON-FLIES — GELINAE I MESOSTENINI 121 



die SO as to accentuate the median tooth; thorax short and stout; 

 mesoscutum poHshed, its punctures moderately small, sharp; meso- 

 pleurum subpolished and with medium-sized, strong punctures and 

 in places some wrinkling that obscures the punctures; apical carina 

 of propodeum evenly, strongly arcuate, not strongly produced for- 

 ward medially but sometimes a little sinuate; areolet unusually large, 

 its sides only wealdy convergent forward, receiving second recurrent 

 vein before the middle; second recurrent vein making a 95° angle 

 with subdiscoideus ; first abdominal segment longer and more slender 

 than in any other Nearctic species, without a basolateral tooth, its 

 median dorsal carinae blunt, extending a little past spiracles, its dor- 

 solateral carinae strong and sharp thi'oughout; postpetiole weakly 

 mat, with some scattered and partly grouped, moderately coarse punc- 

 tures; second tergite mat, with medium sized strong punctures that 

 are separated by about 0.7 their diameter; ovipositor sheath about 

 0.60 as long as front wing. 



Adults occur only from late spring to mid-summer, which indicates 

 a single generation each year. 



This species is represented by four subspecies, which differ in color 

 as keyed and described below. It is closely related to the European 

 {Cryptus) Aritranis quadriguttata (Gravenhorst, 1829), new combina- 

 tion. A. quadriguttata differs from imitator in having the male flag- 

 ellum flattened at the tyloids and the mesopleurum wi'inkled but 

 without distinct punctures. 



1. Second and third tergites black, their apical margins usually narrowly ferrugi" 



nous; range: transcontinental in the Canadian and Hudsonian zones. 



9a. imitator nigriventris, new subspecies 

 Second and third tergites entirely ferruginous 2 



2. Seventh tergite with a median white spot, the spot often very small; apical 



0.12 ± of hind femur at least faintly infuscate, in some females the hind 

 femur largely infuscate; range; Atlantic Ocean to Rocky Mountains in 

 Canadian and Transition zones . . 9b. imitator imitator (Provancher) 

 Seventh tergite without a median white spot; apex of hind femur not infus- 

 cate 3 



3. Fifth tergite black; basal half of first abdominal segment more or less infus- 



cate, especially in males; apical part of female abdomen black; range: Al- 

 berta, British Columbia, Washington, Oregon, and Idaho. 



9c. imitator monticola, new subspecies 

 Fifth tergite ferruginous, or in male sometimes partly infuscate; basal half of 

 first abdominal segment not infuscate; apical part of female abdomen fer- 

 ruginous; range: California . . 9d. imitator ruficauda, new subspecies 



9a. Aritranis imitator nigriventris, new subspecies 



Coloration as in the subspecies imitator and monticola except that 

 abdomen is black, the narrow apical margin of second tergite, some- 

 times thyridiae, and sometimes narrow apical margin of third tergite, 

 ferruginous. 



589900—62 9 



