ICHNEUMON-FLIES, PART 2\ EPHIALTINAE 37 



This subgenus is found in the Holarctic and Oriental regions and 

 is represented by numerous species both in North America and in 

 Eurasia. Among the Nearctic species there are five species groups as 

 indicated in the key to females and the group descriptions. 



Keys to the Nearctic species of the subgenus Scambus 



MALES 



1. Head very thick (not more than 1.65 times as broad as long) ; thorax elongate, 



subcylindrical; hind coxa unusually slender (not more than 0.66 times as 



deep as long). Ephialtoides group (p. 40) 2 



Head not especially thick (at least 1.75 times as broad as long) ; thorax moder- 

 ately stout; hind coxa not especially slender (at least 0.66 times as deep as 

 long), various groups 4 



2. Front femur with a broad, rather deep excision beneath. 



2. ephialtoides Cushman 

 Front femur without an excision beneath 3 



3. Hind tibia whitish, with a narrow subbasal and a broad apical fuscous annulus; 



middle coxa pale j^ellowish except on inner side at base. 



1. protentus, new species 



Hind tibia rather indistinctly banded, the pale median annulus usually suffused 



with brownish and broadly interrupted beneath; middle coxa brownish or 



blackish except at apex 3. longicorpus, new species 



4. Scape whitish beneath, except sometimes at the base 5 



Scape blackish beneath, except sometimes narrowly at the apex .... 12 



5. Front femur slender and without an excision beneath. 



5. vesicarius (Ratzeburg) 



Front femur moderately stout and with a single or a double excision 



beneath 6 



6. Front femur with a single excision beneath 7 



Front femur with a double excision beneath 10 



7. Front femur with a very broad, median excision beneath. 



18. decorus, new species 

 Front femur with a narrow, preapical excision beneath 8 



8. Front femur with a very shallow, preapical excision beneath; front and middle 



femora pale yellowish 16. hispae (Harris) 



Front femur with a moderately deep, preapical excision beneath; front and 

 middle femora usually mostly reddish 9 



9. Clasper narrowly rounded at apex; middle coxa reddish. 



17. nigrifrons (Viereck) 

 Clasper broadly rounded at apex; middle coxa pale yellowish. 



6. imparis, new species 



10. Excised region of front femur distinctly coriaceous; hind coxa usually black. 



15. nucum (Ratzeburg) 



Excised region of front femur without distinct, coriaceous sculpture; hind 



coxa usually reddish 11 



11. Front and middle femora reddish; front femur with a distinct, double excision 



beneath 14. tecumseh Viereck 



Front and middle femora pale yellowish; front femur with a very weak, double 

 excision beneath 13. transgressus (Holmgren) 



12. Front femur without an excision beneath 13 



Front femur with an excision beneath 14 



