132 tT. S. NATIONAL MUSEUM BULLETIN 216 



Color more or less as described under the subspecies D. messor 

 perlongus. 



The male is distinguished by the clasper, which has its apex 

 squarely truncate but with the corners rounded. The female is very 

 similar to that of D. populneus. It is distinguished from populneus 

 as noted in the key. 



This species is Holarctic. It is divisible into one European and 

 two Nearctic subspecies as keyed and described below. The two 

 Nearctic subspecies are distinguishable over most of their range, but 

 in the Canadian zone of Canada there is a broad zone of overlap and 

 intergrades, where the assignment of many of the specimens to an 

 individual subspecies is difficult and somewhat arbitrary. We have 

 seen 3 c? and 59 which are so exactly intermediate that a subspecific 

 assignment has not been possible. These are from Boulder, Colo.; 

 Aweme, Man.; Sudbury, Ont.; Covey Hill, Que.; and Indian 

 Head, Sask. 



MALES 



1. Outer side of middle coxa with a faint median swelling; punctures on outer 



side of middle coxa a little denser than elsewhere on the coxa; stigma light 

 brown, the edges dark brown; hind legs less contrastingly marked; range: 



Europe 8c. messor messor (Gravenhorst) 



Outer side of middle coxa with a distinct median swelling ; punctures on outer 

 side of middle coxa about twice as dense as elsewhere on the coxa; stigma 

 blackish brown, somewhat paler centrally; hind legs more contrastingly 

 marked 2 



2. Face with moderately coarse punctures and moderately dense hairs; under 



side of front trochanters moderately flattened and with moderately fine and 

 dense punctures, the punctures no finer and only a little denser than on the 

 apical part of the femur above; punctures on baeal third of front femur 

 below only a little denser than normal; range: Rocky Mts. to Pacific and 

 eastward in the Canadian zone . . . 8a. messor sparsus, new subspecies 

 Face with rather fine, very dense punctures and very dense hairs; under side 

 of front trochanters and of basal third of front femur strongly flattened and 

 with very fine and dense punctures; range: Atlantic to Rocky Mts. 



8b. messor perlongus (Cresson) 



FEMALES 



1. Stigma light or medium brown, the edges darker; range: Europe. 



8c. messor messor (Gravenhorst) 

 Stigma dark brown or blackish 2 



2. Punctures on lateral 0.1 of face irregularly arranged, not leaving an impunctate 



strip next to eye; subdorsal hair sockets on front face of hind femur separated 

 by about 1.2 the length of the hairs; range: Rocky Mts. to Pacific and east- 

 ward in the Canadian zone 8a. messor sparsus, new subspecies 



Punctures on lateral 0.1 of face usually in a single vertical row paralleling the 

 eye margin and leaving the rest of this area impunctate; subdorsal hair 

 sockets on front face of hind femur separated by about 0.9 the length of the 

 hairs; range: Atlantic to Rocky Mts. . . . 8b. messor perlongus (Cresson) 



