252 PROCEEDINGS OF THE NATIONAL MUSEUM vol. no 



remove those species with the antennae inserted rather far from the 

 base of the beak. The remaining species are spHt into two groups 

 based on iiniserially or biserially pubescent elytral intervals. 



Generally the beak and secondary sexual characters of the male 

 are the best diagnostic specific characters. Other characters include 

 the proportions of the prothorax and elytra, the sculpturing of these 

 parts, and the flatness or convexity of the elytral intervals. 



The following explains methods not included in Kissinger (1957b). 

 In giving the measurements of the scutellum the length is always listed 

 first; the same applies to measurements of the antennal club. In the 

 description of the prothorax the approximate diameter of the punctures 

 is given. This may vary somewhat on the same specimen. If the 

 variance is great the range of variation is approximated; in general it 

 is small so that the measurement given represents an average. To 

 indicate approximate robustness of the legs the relation of width to 

 length of tlie front femur is indicated. If the legs are slender the 

 number of times the front femur is longer than wide will be about 

 four, if the legs are stout it will be about three. The male of A. hrun- 

 nicornis Fall is an example of very robust legs, in which case the middle 

 femur is only 2.25 times as long as wdde. 



As an aid to identification, in the key are included the states or 

 provinces of Canada, the United States, and Mexico from which the 

 species are known. In the case of extensive distribution an attempt 

 w^as made to indicate the extremes of the range. 



Key to males of New World species of subgenus Trichapion 



1. Integument nearly concealed bj' dense white scales; elytral intervals with 



three or four rows of scales; antennae inserted at basal fourth of beak 



(Southern California, Arizona) albidulum Fall (p. 260) 



Integument not concealed by vestiture, dorsal surface of prothorax and 

 elytra with fine pubescence; elytral intervals generally with one or two rows 

 of fine scales or antennae inserted near middle of beak 2 



2. Three pairs of tibiae mucronate, anterior pair sometimes minutely so; pro- 



thoi-ax somewhat v/ider at middle than base 3 



Not more than two pairs of tibiae mucronate 9 



3. Dorsal margin of antennal scrobe oblique, angulate above antennal inser- 



tion 4 



Dorsal margin of antennal scrobe evenly descending to below eye ... 5 



4. Mucrones denticulate; second elytral interval with two or more rows of fine 



scales; in dorsal view beak not strongly expanded at antennal insertion and 

 sUghtly attenuate apically (Montana, Manitoba). 



commodum Fall (p. 380) 



Mucrones simple; second elytral interval with one row of fine scales; in dorsal 



view beak strongly expanded at antennal insertion, strongly attenuate to 



apex (Florida) confertum Smith (p. 381) 



5. Beak as long as head and prothorax combined, deflexed at apical fourth; 



mucrones 2 and 3 dentate (San Luis PotosI) . cor>'i, new species (p. 285) 

 Beak shorter than head and prothorax combined 6 



