Z PROCEEDINGS OF THE NATIONAL MUSEUM vol. 72 



LIMITS OF GROUP 



As to the insects treated we may remark that the Heteroptera 

 can logically be grouped into a limited number of comprehensive 

 assemblages. These are often called superf amilies, but in our opinion 

 family rank in most cases is sufficient. Adverting to Pentatomidae 

 in particular we believe that since the principal subdivisions of this 

 group differ from each other for the most part by relative characters 

 or merely by different combinations of similar characters, they are 

 preferably treated as subfamilies. 



We have found only one character that holds throughout the vast 

 assemblage of Pentatomids, namely, the presence on the sternites 

 near the spiracles, of sensory hairs which are not closer to the median 

 line on the first and second visible sternites than on the others. 

 (Figs. 3, 23, 24.) These hairs are normally 2 in number on each side 

 while in most of the other families possessing them they are normally 

 3 in number.^ In Pentatomidae the spiracles are almost always on 

 the ventral surface and equally or almost equally distant from the 

 sensory hairs on all sternites, the only known exceptions occurring 

 in the genus G orinbelaena in which there are some species that have 

 the spiracles of the posterior segments situated in the margins of 

 the sternites. In all Pentatomidae known to us, with the exception 

 of the Urolabidinae and the genus Amnestus, there is a group of 

 four or more short, usually stout, and curved spines or bristles, 

 frequently set in a notch, at varying distances from the apex, on 

 the anteroventral surface of the fore tibia. These bristles we have 

 not found in any other family we have examined. The number of 

 antennal and tarsal segments are not constant enough to be avail- 

 able for recognition of the group Pentatomidae in the broad sense. 



The assemblage of Pentatomidae treated in this paper are distin- 

 guished from the remainder of the family by the fore wings being 

 about tAvice as long as the abdomen and having thinned areas 

 (almost fractures) adapting them for folding. These characters 

 may not have phylogenetic significance, but they serve for recogni- 

 tion of two interesting and little understood subfamilies of New 

 World heteroptera, and of one from the Old World with which they 

 might be confused. These insects, for the most part, are relatively 

 broad in proportion to their length (figs. 1-3), a character which, 

 with the complete covering of the abdomen by the scutellum and the 

 usually inflated shape of the latter (figs, 13-17), gives them a semi- 

 globose appearance. This is especially true of the nymphs of Cano- 

 pinae and Megaridinae, while those of the Coptosomatinae (some of 



* For fuller discussion and illustration of the " trichobothria " see Tullgren, A., Ent, 

 Tidskr., vol. 39, 1918, pp. 113-133, 11 figs., and Malloch, J. R., BuU, Brooklyn Ent, Soc, 

 vol, 16, 1921, pp. 54-56, 16 figs. 



