448 U. S. NATIONAL MUSEUM BULLETIN 216 



3. Genus Odontocolon 



Figure 305,b 



Odontomerus Gravenhorst, 1829, Ichneumonologia europaea, vol. 3, p. 851. Name 

 preoccupied. Type: Ichneumon dentipes Gmelin; designated by Westwood, 

 1839. 



Odontocolon Cushman, 1942, Proc. Ent. Soc. Washington, vol. 44, p. 179. New 

 name. 



Head and body not, or only moderately flattened ; apex of mandible 

 with two subequal teeth; frons without a median tubercle or horn; 

 female flagellum not specialized as in Xorides; epomia absent or rudi- 

 mentary; hind femur thickened, beneath with a strong median tooth; 

 first abdominal segment rather slender basally and enlarged apically, 

 a little bent near the middle; second tergite without oblique basal 

 grooves; first and second tergites polished, smooth or more or less 

 aciculate or punctate, sometimes more or less mat; apical part of 

 ovipositor weakly compressed, the ventral valve with about five 

 ridges, basad of which there is no roughened area, the dorsal valve 

 with a few weak, very oblique grooves (fig. 331,g). 



This is a Holarctic genus, with numerous species. There are three 

 species groups, which are better marked in the female than in the male. 

 The distinction of species is in many cases difficult. Our western 

 species related to dichrous (brevicaudus , dichrous, parvum, curtum, 

 and sierrae) are only weakly differentiated. Determination of their 

 males is often difficult and sometimes not possible on the known 

 characters. The "species" dichrous contains a number of distinguish- 

 able populations, some of which will probably prove to be distinct 

 species or namable subspecies. 



The descriptions of females below are moderately complete, but 

 those of the males sketchy. Males have about the same characters 

 as females of the same species, but with the following exceptions: 

 flagellar segments more evenly cylindric and specific differences in 

 lengths of segments less pronounced than in females; punctation of 

 mesoscutum, hind femur, and second abdominal tergite more uni- 

 formly dense, without as great differences in density between species 

 as in the females; propodeum a little longer and flatter, resulting in a 

 relatively shorter petiolar area; propodeal spines tending to be shorter 

 than in female; propodeal differences between species with the same 

 specific tendencies as in female but a little less pronounced ; differences 

 in proportions of tarsal segments with the same specific tendencies as 

 in the females but the differences less pronounced; abdomen black in 

 most males, even when the female abdomen is ferruginous. A key 

 to males has been worked out and there is a color description of each 

 under the species, but for most structural characters comparison with 



