GRASSHOPPERS — GURNEY AND BROOKS 7 



Figures l,a,d,e; 2 (all except/); 9J,g,h-2; and 15 were made by- 

 Arthur D. Cushman, Entomology Research Division, U. S. Depart- 

 ment of Agriculture. All other drawings and the maps were made by 

 the senior author. 



Systematic Treatment 



Key to species and subspecies of the mexicanus group of Melanoplus 



(Based on males) 



1. A distinct mesosternal swelling or "hump" present (fig. l,d,f,g) 2 



Without a mesosternal "hump," or with a weakly developed one (fig. l,e) . 7 



2. Dorsal valve of aedeagus (fig. Z,k) of a general circular shape, appearing thin 



and parchment-like, and with a triangular projection (x of fig. S,k) on the 

 dorsal rim; subgenital plate usually without twin apices well developed 

 (fig. ll,a-l,2,4,5), occasionally with them distinct (fig. ll,a-3). (Distri- 

 bution: figs. 12, 13) bruneri Scudder 



Dorsal valve variously formed (fig. 3,a-h) but not with a generally circular 

 shape as in fig. 3,fc; subgenital plate normally with well-developed twin 

 apices (fig. 9,/,/i-2), best seen in posterior view (fig. 10,«-x) 3 



3. Dorsal valve of aedeagus strongly recurved laterally and posteriorly (fig. 3, a) , 



the hornlike structure heavily sclerotized (pi. 2,d). (Distribution: fig. 14). 



spretus (Walsh) 

 Dorsal valve (fig. 3,6-/) variously shaped, but not as in opposite category . 4 



4. Dorsal valve of aedeagus with a lateral projection (p) from its ventrobasal 



region (fig. 3,&-l, lateral view; fig. 3,6-2, latero ventral view). (Distribution: 



figs. 4, 6) mexicanus (Saussure) 



Dorsal valve without a lateral projection from its ventrobasal region . . 5 



5. Dorsal valve of aedeagus (fig. 3,c) typically produced into a blunt hook or 



knob at lateroanterior angle (y) , especially by a carina (x) which separates 

 main lateral surface from a concave, heavily sclerotized ventroanterior 

 marginal area (z). (Distribution: fig. 6). 



bilituratus vulturnus, new subspecies 



Dorsal valve (fig. Z,d-f) without a hook or knob at lateroanterior angle, and 



without a carina on main lateral surface, though the ventroanterior margin 



usually recurves as a lip (z of fig. Z,d) 6 



6. Dorsal valve of aedeagus appearing inflated, typically with a concave anterior 



margin (x of fig. Z,d) and with a sinuate margin (z) of the recurved anterior 

 flap (y), the latter wide. (Distribution: fig. 6). 



bilituratus defectus Scudder 



Dorsal valve with little appearance of inflation, without a concave anterior 



margin, and with a relatively straight margin of the recurved anterior flap, 



the latter of variable width, often narrow (fig. 3,e). (Distribution: figs. 



5, 6) bilituratus bilituratus (Walker) 



7. Cercus (fig.7,A) narrow; subgenital plate usually with twin apices (fig. 9,ft-2), 



though variable and occasionally poorly developed (fig. 10,z) ; aede- 

 agus with apex produced dorsally beyond the base of dorsal valve (figs. 

 2,fc; 3,i); dorsal valve extending primarily dorsoanteriorly. (Distribution: 

 fig. 14) devastator Scudder 



