REVISION OF LISTROCHELUS SAYLOR 63 



Claw with a strong to moderate tooth, position of latter variable, 

 claw never with serrations or pectinations; tarsi never densely- 

 pilose; vertex of head plane, never transversely carinate (North 

 and South America) Phyllophaga Harris 



Claw finely or coarsely serrate to pectinate, with or without a 

 larger intercalated triangular tooth; vertex usually with a well- 

 marked transverse carina, the latter reduced in some species 

 and entirely absent in some; tarsi in some few species densely 

 pilose or ciliate in male (Southwestern United States and 

 Mexico) Listrochelus Blanchard 



KEY TO THE MALES OF LISTROCHELUS 



1. Head densely, coarsely, and entirely punctate behind 

 transverse carina of vertex; tarsal claws pectinate or 

 serrate along a single margin (figs. 2, /, i) without a 

 larger intercalated tooth (serrations of margin frequently 



hardly noticeable); not densely hairy above 2 



Head rarely punctate behind transverse carina and then 

 only at sides, with at least a large portion of vertex 

 impunctate, more commonly the entire surface posterior 

 to carina impunctate; claw variably serrate or pectinate 

 along a single or double margin; if with characters as in 

 preceding couplet, then with dense short hair dorsally 

 (pilosipes) 3 



2 (1). Claw with serrations obvious to nearly absent (fig. 2, j); 



antenna unicolorous rufotestaceous, club usually shorter 

 than, or subequal to, funicle (genitalia, fig. 3, a-c) — timida (Horn) 

 Claw definitely pectinate; antennal club testaceous, lighter 

 in color and slightly longer than funicle (genitalia, 

 fig. 3, d-f) snowi, new species 



3 (1). Claw definitely pectinate (fig. 2, /) 4 



Claw serrate (figs. 2, h, i) , seiTations rather strong to faint 23 



4 (3). Claw pectinate along two margins (fig. 2, g) 13 



Claw pectinate along one margin (fig. 2,/) 5 



5 (4). Genitaha symmetrical (fig. 12, a); transverse carina of ver- 



tex obsolete, clypeus plane; dorsal surface glabrous or 

 nearly so; sixth abdominal segment plane {cavata and 



related species) 6 



Genitalia asymmetrical (figs. 5, c, h); transverse carina 

 strong, or if weak then clypeus strongly tumid at base; 

 densely hairy above, or if glabrous then sixth abdominal 

 segment either with a deep fovea or large and flattened 

 and with scabrose, setigerous punctures 9 



6 (5). Genitalia in en face view with apices bluntly rounded or 



bluntly pointed, apices never reflexed (fig. \2, d, g) 7 



Genitalia in en face view with apices narrow and pointed 

 and strongly to moderately reflexed toward sides (fig. 

 12,0 -" 8 



7 (6). Genitalia with tips pointed but bluntly so, not at all re- 



flexed toward sides (fig. 12, d-f) (Mexico and New 



Mexico) cavata (Bates) 



Genitalia tips bluntly rounded, neither pointed nor re- 

 flexed (fig. 12, g-i) (Colorado and Mexico) micros (Bates) 



