400 PROCEEDINGS OF THE NATIONAL MUSEUM vol. no 



tribe. But the hypostoma is long and the labial sclerite is roughly 

 triangular in shape, although the ventral part of the sclerite is broad 

 as in the Pimplini. In all tribes of the Pimplinae, with the exception 

 of the Labenini and Xoridini, the hypostomal spur meets the stipital 

 sclerite on or near the point of meeting of this and the labial sclerite. 

 In the Pimplini this results in the sclerites around the mandibles 

 having a ringlike appearance. Apart from this one character the 

 groups in the Pimplinae are distinct. 



Since the Pimplini (with the possible exception of Itoplectis) are 

 endoparasites which emerge from the pupa of the Lepidopterous host, 

 and the remaining tribes of the Pimplinae (with the possible exception 

 of some Acaenitini) are ectoparasites, differences in larval structure 

 might be expected. The Pimplini, with their large, toothless man- 

 dibles and well-developed epistomal and pleurostomal sclerites resemble 

 to some degree other ichneumonid larvae with similar habits (see 

 pp. 502,505,506). 



Beirne (1941) in his classification of larval Ichneumonidae has 

 placed the Polysphinctini, Rhyssini, Ephialtini, and Xoridini with the 

 Cryptinae. This has not been followed in the present study for, 

 although the Pimplini differ in many aspects from the Ephialtini and 

 similar tribes, the position of the hypostomal spur gives a common 

 character for the subfamily. Where this character is not shown 

 clearly, as in the Labenini and Xoridini, the remaining characters 

 indicate the relationships of the tribe. In the Labenini the form of 

 the mandible closely resembles that of the Ephialtini. In the Xoridini 

 the general form of the head sclerites, particularly the labial sclerite, 

 resembles that of most Pimplinae, rather than any other Ichneumonid 

 group. The form of the mandible of the Xoridini differs from that of 

 all other ichneumonids. 



It is significant that the Acaenitini and Theroniini show characters 

 resembling those of both the Pimplini and the Ephialtini and similar 

 tribes. 



Larval Key 



1. Setae on body longer than blade of mandible Polysphinctini 



Setae on body not longer than blade of mandible 2 



2. Labial sclerite sharply pointed ventrally 3 



Labial sclerite not sharply pointed ventrally 4 



3. Ventral point of labial sclerite continuous with sclerite Rhyssini 



Ventral point of labial sclerite appearing as distinct plate at end of sclerite. 



Neoxoridini 



4. Each lateral part of labral sclerite expanded into quadrate-shaped area. 



Labenini 

 Each lateral part of labral sclerite not expanded into quadrate-shaped area . 5 



