1	Elytra with well-marked punctures (Fig. 15E, F); posterior elevation of mesoventrite flat	N. punctatus
–	Elytra with shallowly marked punctures (e.g., Fig. 15A, B); posterior elevation of mesoventrite weakly to sharply carinate	2
2	Coloration of the body rather uniformly brown (Fig. 15A–D)	N. castaneus
–	Coloration of pronotum yellow (see Fig. 16)	3
3	Coloration of the head and clypeus uniformly dark brown (Fig. 16D); posterior elevation of mesoventrite weakly carinate; ventral surface densely pubescent (Fig. 16C)	N. tricolor
–	Coloration of the head brown, with orange clypeus (Fig. 16H); posterior elevation of mesoventrite sharply carinate; ventral surface scantily pubescent (Fig. 16G)	N. hesperus