20 MISC. PUBLICATION 4 7 0, U. &. DEPT. OF AGRICULTURE 



Legs. — The femora are alike in the two sexes, except that sometimes 

 they are more robust in the males, and nearly all the species have a 

 large tooth, which is dentate or entire on the" outer margin, but in a 

 few the tooth is absent. In nearly all the species sexual differences 

 are found on the anterior tibia, but in a few there is scarcely any 

 difference between the two sexes. In the male the anterior tibia is 

 usually more or less arcuate, and is armed on the inner margin with 

 a single tooth, a number of small teeth, or an apical dilation. This 

 character is very useful in separating the males from allied species, 

 but some allowance must be made for a slight variation in the 

 shape of the apical dilation in some species. In the female the anter- 

 ior tibia is less arcuate and without teeth or dilations on the inner 

 margin. The middle tibia is usually straight in the female, but in 

 the male it is not so strongly arcuate as the anterior one, slightly 

 thickened at the apex in a few species, and in femorata auct. and 

 merhelii armed with a number of small teeth on the inner margin 

 similar to those of the anterior tibia. In one species, scabripennis, 

 the posterior tibia of the male is arcuate. 



Genitalia. — The male genitalia are strongly chitinous, and com- 

 posed of the lateral and median lobes. The basal piece and lateral 

 lobes are consolidated, allowing the median lobe to be extended beyond 

 the tips of the lateral lobes. The genitalia show considerable differ- 

 ences in shape and sculpture, but very little variation in the same 

 species; however, there is a slight variation in the width of the 

 dilation of the lateral lobes in some specimens of the same species. 

 The genitalia are very useful for separating species, and especially 

 in checking individual specimens that are more or less abnormal. 



KEY TO THE SPECIES OF CHRYSOBOTHRIS 



1. Elytra clothed with more or less conspicuous hairs, sometimes only 



barely indicated apically 2 



Elytra without hairs, except sometimes on lateral margins posteriorly. 23 



2. Anterior femur toothed 3 



Anterior femur not toothed 22 



3. Body above bright green, blue, or violaceous blue 4 



Body above dark bronzy brown to coppery brown, rarely dull bronzy 



green, sometimes with a greenish reflection in different lights 5 



4. Tooth on anterior femur coarsely dentate on outer margin; lateral 



margins of elytra serrate posteriorly (1) cyanella Horn, p. 30. 



Tooth on anterior femur not dentate on outer margin ; lateral margins 

 of elytra not serrate posteriorly (2) boharti Van Dyke, p. 32. 



5. Pronotum convex, without a median depression 6 



Pronotum more or less flattened, or with a distinct median depression _ 14 



6. Body narrowly elongate, subcylindrical 7 



Body broadly elongate 8 



7. Anterior tibia of male with an indistinct dilation near apex; median 



lobe of male genitalia acute at apex; last visible abdominal 

 sternite of female subtruncate or slightly rounded at apex 



(3) lixa Horn, p. 34. 



Anterior tibia of male with a distinct dilation near apex, male genitalia 



twice as long as in lixa, and with the median lobe rounded at 



apex, last visible abdominal sternite of female transversely 



sinuate at apex (4) arizonica Chamberlin, p. 36. 



8. Each elytron with four more or less distinct, smooth, longitudinal 



costae, usually extending from near apex to base 9 



Each elytron without, or with one to three more or less distinct, 



longitudinal costae, which do not extend to base 13 



9. Costae on elytra elevated posteriorly 10 



Costae on elytra not elevated posteriorly 12 



