364 U. S. NATIONAL MUSEUM BULLETIN 216 



My inclination is to follow Hellen and place the genus in the tribe 

 Delomeristini or in the Theroniini of Townes. Generic relationships 

 will be more clear when the larvae and biology of the species are 

 better known. 



This genus comprises species that are very similar in general ap- 

 pearance. The North American species can be placed in two more 

 or less natural groups which I call the novita group and the japonica 

 group. The shape of the apical portion of the ovipositor is the single 

 character used to distinguish the two. It may be that the members 

 of the japonica group are parasitic only on sawflies and those of the 

 novita group parasitic on Lepidoptera or other insects in certain 

 ecological niches. 



Although the black color and habitus of the species of this genus are 

 typical of the Ephialtini, the sculpture of the abdomen and the 

 presence of an areola and petiolar area on the propodeum will quickly 

 identify them. The abdomen of Delomerista species is usually finely 

 granular, shagreened or coriaceous with very fine shallow scattered 

 punctures, and sometimes more or less polished. Species of ephialtine 

 genera have the abdomen more polished with comparatively large, 

 coarse punctures. The Delomerista females can be further distin- 

 guished by the pale malar space and mandibles. They can also be 

 separated from all ephialtine species, except those of Perithous, by 

 the complete lack of a large basal tooth on the claws. 



The compressed ovipositor is also found in some other ephialtine 

 species, but in the Nearctic region only a few species of Scambus have 

 it as compressed as in Delomerista. 



The males of the genus, except those of texana (Cresson), are not 

 included in the specific descriptions. They have been placed only 

 in species groups. Genitalic dissections failed to show characters for 

 further separation. 



It is entirely possible that there are additional species in the ma- 

 terial studied, but until more specimens and further biological facts 

 are available the variations can only be noted. 



Keys to the Nearctic species of Delomerista 

 males 



1. Clypeus convex; abdominal tergites finely granular in sculpture. 



1. texana (Cresson) 

 Clypeus not convex; abdominal tergites beyond the third segment coria- 

 ceous 2 



2. Hind tibia fully as long as femur and trochanters combined. Novita group 

 Hind tibia not as long as femur and trochanters combined. Japonica group 



