1.
.
.
Legs with femora bicolored, light brown with darker brown apex
(Fig. 1).
.
       
1'.
. 		Legs with femora unicolorous, dark brown to black.

.2
       

side

Fig. 1. Right ventral view of L. capreolus, female showing light brown femora with darker apices.

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2(1). Labrum subtriangular with narrowly rounded apex in both sexes (Figs. 2-3). Male mandibles multidentate, always longer than head and prothorax combined.

Lucanus elaphus (Fabr.)
 

2'.

 Labrum pentagonal or subrectangular, apex truncate in both sexes (Figs. 4-7).  Male mandibles never longer than head and prothorax combined, multidentate or not.

3
     
67
 ...............
57
Fig. 2. Head of male L. elaphus (dorsal view) with arrow showing labrum (labrum inset to show shape).   Fig. 3. Head of female L. elaphus (dorsal view) with arrow showing labrum (labrum inset to show shape).
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3(2).
 Male mandibles usually multidentate.  Labrum subquadrate in both sexes, length nearly subequal to width (Figs. 4-5).  Central and eastern North America.
 
3'. Male mandible with 0-1 internal teeth.  Labrum narrow, length less than 1/2 width (Figs. 6-7).  Western North America (AZ, CO, NM, UT, and neighboring parts of México).

Lucanus mazama (LeConte)
 
Fig. 4. Head of male L. placidus (dorsal view) with arrow showing labrum (labrum inset to show shape).
74
  
Fig. 5. Head of female L. placidus(dorsal view) with arrow showing labrum (labrum inset to show shape).
87
   
 
Fig. 6. Head of male L. mazama (dorsal view) with arrow showing labrum (labrum inset to show shape).
77
  
Fig. 7. Head of female L. mazama (dorsal view) with arrow showing labrum (labrum inset to show shape).
99