ICHNEUMONID FINAL INSTAR LARVAE — SHORT 417 



It has been already noted that the Acaenitini have characters 

 similar to those of the two groups of the Pimplinae, the Ephialtini 

 and similar tribes, and the Pimplini. 



In the genus Arotes the epistoma and pleurostoma are moderately 

 sclerotized and broad; the hypostoma is moderately sclerotized but 

 very slender; the hypostomal spur is broad and very lightly sclerotized ; 

 the stipital sclerite is short, broad and very lightly sclerotized; the 

 labial sclerite is roughly triangular in shape, but the ventral part is 

 much broader than the lateral parts as in the Pimplini ; the maxillary 

 palps each bear one large, round sensillum and a group of smaller 

 sensilla; each labial palp bears one large round sensillum and one 

 small sensillum; the labral sclerite is absent and there are two prom- 

 inent groups of sensilla on the labrum; the mandibles resemble those 

 of the Pimplini in having a large blade and no teeth; the antennae 

 were not visible on the specimen; the spiracular atrium is oval, and 

 the closing apparatus, which is relatively long and with thin walls, 

 is situated adjacent to the atrium; the skin has very small setae but 

 no spines. 



Coleocentrus excitator (Poda) is figured by Baumann (1933). The 

 antenna of this species appears to be disc-shaped. The epistoma 

 appears to be incomplete, but the figure given is too small to make 

 this point clear. 



Subfamily Adelognathiiiae 



FiGUKE 11a 



Members of this subfamily are gregarious external parasites on 

 sawfly larvae. Adelognathus and related genera have been placed 

 as a tribe of Tryphoninae by some authors. In the present study it 

 was found necessary to consider this group as a subfamily since the 

 form of the mandible, the absence of an epistoma and a labral sclerite, 

 the presence of a prelabial sclerite and of a clearly papilliform an- 

 tenna '^ and the absence of spines on the skin all separate Adelognathus 

 from other genera of the Tryphoninae. I have been unable to dis- 

 cover whether Adelognathus possesses the stalked egg that is charac- 

 teristic of the Tryphoninae. The ovaries of an adult were examined 

 and the eggs present did not appear to be stalked. 



Adelognathus britannicus Perkins (GCV), A. pallipes (Gravenhorst) 

 (GOV) and Adelognathus sp. (GCV) were examined. 



The dorsal part of the cranium is sufficiently sclerotized to appear 

 dark; the epistoma is unsclerotized except for small projections above 



"• A papilliform anteima is present in Hybophanes scabriculus (Gravenhorst) and Phptodietus pulcherrimus 

 (Cresson) (Simmonds, 1947) of the Tryphoninae. The antenna was not visible in the specimen of P. 

 pulcherrunus examined in the present study. In the remainder of the Tryphoninae the antenna is not 

 papilliform, although a relatively large, rounded sensillum may be present in the middle of the disc-shaped 

 antenna as in Idiogramma. 



