pepsinae: tribe macromerini 145 



The New World species have more structural uniformity. There are 

 many species in the Neotropic region and a large portion of the 

 Nearctic species are intrusions from that area. It has not been 

 possible to separate our species into sharply defined groups, but the 

 following resemblances might be pointed out: A. flavicoxae, inermis, 

 variolarum, and adjunctus agree in the polished female pygidium, 

 lack of bluish iridescence, fulvous femora and tibiae, and unspecialized 

 mandible and clypeal margin of the male. A. mellipes and mexicanus 

 agree in the mat female p3^gidium, lack of bluish iridescence, bent 

 mandible of the male, and thickened apical margin of the male clj'peus. 

 A. mollis, caerulescens, architectus, and nigrellus agree in the polished 

 female pygidium, presence of bluish iridescence, and the unspecialized 

 mandible and clypeal margin of the male. 



Probably all species of the genus nest in mud cells and the charac- 

 teristic mental bristles and large cl3T)eus of the female are presumed 

 to aid in carrying mud pellets for nest construction. Absence of 

 teeth on the outside of the hind tibia seems to be another structural 

 character correlated %vith these nesting habits, but the functional 

 reason is not entirely clear. Possibly the tibial teeth when present, 

 aid in digging or in pushing into and out of nest tunnels in the ground 

 and, if so, would not be needed in species making nests of mud cells. 



Keys to the Nearctic species of Auplopus 



MALES 



(Males of variolarum, inermis, mollis, and mellipes meridianus are 



unknown.) 



1. Pronotum margined with white on its hind edge and naost of its front edge; 



first tergite and coxae fulvous 4. adjunctus (Banks) 



Pronotum not margined with white; first tergite and often the coxae black or 

 blackish 2 



2. Clypeus with part of its apical edge much thickened (see from below) ; mandi- 



ble much more strongly curved at the middle than elsewhere 3 



Clypeus with its apical edge thin; mandible evenly curved throughout . . 5 



3. Apical edge of clypeus with a large rounded notch on each side of the middle; 



face black, with a v/hite vertical line adjacent to the eye; seventh tergite 



without a conspicuous white spot 6. mexicanus (Cresson) 



Apical edge of clypeus without notches; face white, with or without a small 

 median dark area; seventh tergite with a conspicuous white spot, sub- 

 species OF MELLIPES 4 



4. Middle and hind femora and tibiae fulvous . . . 5a. mellipes mellipes (Say) 

 Middle and hind femora and tibiae black. 



5c. mellipes variitarsatus (Dalla Torre) 



5. Coxae entirely fulvous; thorax black, without iridescence. 



1. flavicoxae (Banks) 



Coxae blackish or largely so ; thorax blackish, with a distinct bluish or greenish 



iridescence 6 



