ICHNEUMON-FLIES, PART 2: EPHIALTINAE 15 



the United States. There is a marked reduction in abundance in the 

 region of the southern limits of the Upper Austral zone, especially in 

 eastern North America, and there are very few records from the 

 Austroriparian faimal area. A few species are found in the Lower 

 Sonoran faunal area. In the Neotropics the genus is represented by 

 several species that form a distinctive subgenus confined to that region, 

 except for a single species found in the western portion of the Nearctic 

 region from California to southern British Columbia. 



In this account 26 species plus 4 subspecies are recognized. Exclud- 

 ing alboricta (Cresson), which elsewhere in this publication (p. 162) 

 Townes places in Acropimpla, all the species listed by Townes in 1944 

 are retained in Scambus. One species, lithocolletidis (Ashmead), has 

 not been identified beyond verifying its generic position from the rather 

 poorly preserved type specimen. It seems to belong in the nominate 

 subgenus. Changes in the Townes arrangement include the removal 

 of nigrifrons (Viereck) from synonymy with hispae (Harris) and its 

 recognition as a valid species, the transfer of innominatus (Viereck) 

 from the synonymy of hispae to that of transgressus (Holmgren), the 

 synonymizing of bicoloripes (Ashmead) with brevicornis (Gravenhorst) , 

 and the subordination of euurae (Ashmead) to the rank of a subspecies 

 of vesicarius (Ratzeburg) . Additions include the recognition of nucum 

 (Ratzeburg) and the nominate subspecies of vesicarius (Ratzeburg) 

 from North America, the descriptions of 13 new species and 2 new sub- 

 species from the Nearctic region, and the division of the genus into 5 

 subgenera. 



2. Genus Scambus 



Figures 285,b; 286,a 



Small to medium-sized, slender to rather stout species, the Nearctic 

 species with front wing 2.0 to 8.0 mm. long; head usually moderately 

 thin, but occasionally rather strongly thickened; occipital carina com- 

 plete, but often very weak, dipped on the midline above; eye indi- 

 stinctly to very weakly emarginate opposite antennal socket ; cheek at 

 most not more than 0.5 times breadth of base of mandible; antenna 

 about 0.66 times as long as front wing; prepectal carina present; 

 mesoscutum usually with distinct hairs but occasionally almost bare; 

 areolet present, receiving second recurrent distinctly before outer 

 corner; nervellus inclivous to perpendicular, broken definitely below 

 middle or rarely at middle; legs slender to rather stout; front femur of 

 male simple or excised beneath; front tibia of male varying from al- 

 most straight to rather strongly bent; all tarsal claws of female with a 

 large basal lobe; propodeum convex and usually with short, rather 

 weak, dorsomedial carinae at base, but sometimes with dorsomedial 

 carinae rather strong and extending almost to apex; dorsal carinae of 



