D. Veal and E. Freese have collected these in Western Iowa.

Ed sent this: couplet 3 of key in Nebraska scarabs by Paulsen and Ratcliffe (2008):
3a) Head usually bicolored. Pronotum entirely dark or with trapezoidal macula with constriction near anterior margin. Elytra uniformly dark or with variablr pattern and nearly always with dark spot over apical umbone......................................innuba
3b) Head usually reddish brown and darkening to vertex, not distinctly bicolored. Pronotal macula usually complete to basal margin; if not, then broadly rectangular and lacking constriction anteriorly. Elytra not uniformly dark and with variable pattern but only rarely with dark spot over apical umbone.......................undulata