DIAPERINI NORTH OF MEXICO — TRIPLEHORN 375 



V-shaped between coxae, broadly notched in front; epipleura usually 

 abbreviated; terminal segment of hindtarsus at least 1.5 times longer 

 than basal segment which is subequal in length to, or shorter than, 

 the following two segments combined. Male aedeagus with apical 

 sclerite composed of a single piece. 



This genus is very difficult to delimit since there are so few char- 

 acters that are not subject to exceptions. There are many detailed 

 generic descriptions in the literature, but most of them are designed 

 to cover only a limited faunal area and are usually based on the Euro- 

 pean A", haemorrhoidalis (Fabricius). While it is true that most 

 of the species encountered do fit such a description, it was thought 

 best to modify the above diagnosis so as to cover all variations en- 

 countered in the present study. 



The criteria which most firmly unites members of this genus as a 

 natural group are themselves subject to exceptions. The long, loose 

 antennal club, a character shared with Diaperis and similar to those 

 of Palembus and Pentaphyllus, the relatively short basal segment of 

 the hindtarsus, the presence of horns or tubercles on the frons or 

 clypeus or on both, at least, m the males of every species (except 

 possibly N. inermis Champion), the convex prosternal process and the 

 general form of the male aedeagus, all combine to give a very distinct 

 habitus to members of this genus. 



Some previous authors have arbitrarily placed all more or less cy- 

 lindrical species into the genus, but this obscures the relationships 

 and should be avoided. Several members of the genus Platydema 

 (e.g., P. picilahrum, P. subcostatum) are more cylindrical than some 

 of the species of Neomida (e.g., A^. myllocnema, N. suilla Champion). 



Most species have the epipleura abbreviated near the last ventral 

 abdominal sternite, notable exceptions bemg N. picea (Laporte and 

 Brulle) and A^". myllocnema, in which the epipleura extend to the apices 

 of the elytra. 



Considerable variation exists in the punctation, striation, and dorsal 

 vestiture of the elytra. Most species are typically punctate-striate 

 and glabrous as in A^. bicomis and A^. haemorrhoidalis. Others are 

 punctate-striate and clothed with fine setae as in A'^. myllocnema and 

 N. picea, while still others are confusedly punctured as A^^. inermis 

 (Champion) and A^. cioides (Champion). 



The cephalic horns, present to some degree in the males of all spe- 

 cies of Neomida, difler widely in form. The frontal pair may be thin, 

 cylindrical, and straight as in A", bicomis, thick, flattened, and blunt 

 as in A^. myllocnema and A^. suilla, or long and curved as in A^. ferru- 

 ginea and A^. hojffmanseggi (Laporte and Brulle). 



The clypeus may be armed with two small tubercles as in A^. bicomis, 

 N. aeneipennis, and A^. lecontei (Bates), one median tubercle as in A^. 



