18 U. S. NATIONAL MUSEUM BULLETIN 216 



Ovipositor rather strongly to rather weakly compressed, with at least the 

 basalmost ridges on apex of lower valve distinctly oblique, and with most 

 ridges more or less developed dorsally into forward directed teeth; subgenital 

 plate with a large or moderately large, median, basal, membranous excision; 

 apical segment of tarsi not strongly swollen; claws not especially large or 

 stout; propodeum moderately long to rather short, with median carinae, 



when present, short to moderately long 4 



4. Ovipositor rather strongly compressed, with basalmost ridges on apex of lower 

 valve forming an angle of about 40° with its longitudinal axis; propodeum 

 rather long, with distinct, long, dorsomedial carinae; subgenital plate with a 

 moderately large, median, basal, membranous excision; sheath 0.4 to 0.7 



times as long as abdomen Ateleophadnus (p. 27) 



Ovipositor rather weakly compressed, with basalmost ridges on apex of lower 

 valve (except in S. protentus) forming an angle of about 30° with its longi- 

 tudinal axis; propodeum rather short, usually with rather short dorsomedial 

 carinae; subgenital plate with a large, median basal, membranous excision; 

 sheath (except in S. imparis) at least 0.66 times as long as abdomen. 



Scambus (p. 36) 



Subgenus Endromopoda 



Figure 285,b 



Scambus (Endromopoda) Hell6n, 1939, Not. Ent., vol. 19, p. 56. Type: Scambus 

 (Endromopoda) melanopyga (Gravenhorst) ; original designation. 



Submetapleural carina present; propodeum long, with long, rather 

 narrowly separated, parallel or subparallel, dorsomedial carinae; 

 abdominal sternites in female unusually large and broad, with the 

 basal and apical pairs larger than the others, and all except the basal 

 pair with large, aciculate punctures; subgenital plate in female with 

 basal membranous excision small, and often very shallow; sheath 

 about 0.4 times as long as abdomen; ovipositor very strongly com- 

 pressed, with ridges on apex of lower valve at right angles to its 

 longitudinal axis and dorsally not developed into forward directed 

 teeth (fig. 310, c); apical segment of tarsus unusually long (in mid 

 tarsus of male subequal to segment one), and in female strongly 

 swollen and with claws very large and stout; first abdominal tergite 

 in male at least 1.5 times (and usually 2.0 times) as long as wide. 



Most members of this subgenus parasitize insects living within the 

 stems of reeds and grasses. The short, rigid, strongly compressed 

 ovipositor, characteristic of the group, appears well suited to pene- 

 tration between the fibrovascular bundles of monocotyledonous stems. 



The subgenus is represented in both the Palearctic and Nearctic 

 regions and includes one species (detritus) that is Holarctic. 



Key to the Nearctic species of the subgenus Endromopoda 



1. Metapleurum entirely reddish, or with a large reddish spot; abdomen more or 

 less rufopiceous, or with distinct reddish markings; male front femur without 

 an excision beneath; female front trochanter yellowish. 



1. rubescens, new species 



