1. Circumnotal ridge continuous, not interrupted behind eyes (Fig. 7). Posterior margin of paraocular area straight, ending at middle of eye. Prosternal ridge with acute tubercle at anterior end (Fig. 112). Parameres lacking distinct apical teeth, at most with slightly swollen tips (e.g. Fig. 123). South America....................................................................................... jasius species group

— Circumnotal ridge (Fig. 8) effaced behind each eye. Posterior margin of paraocular area curved, ending at posterior angle of eye. Prosternal ridge simple, not tuberculate anteriorly. Parameres with apical teeth (may be reduced) (e.g. Fig. 169-170, 217). Distribution variable................. 2

2(1). Apical processes of parameres (Fig. 169-170) projecting laterally, not visible from side, tip of paramere not appearing at all hooked in profile (although hook-like processes often visible from above); parameres elongate, usually lacking prominent basal angle. Male and female with trituberculate cephalic carina. Mesoamerican (Fig. 172)...................... pluto species group

— Apical processes of parameres (Fig. 217) elevated dorsally, tip (viewed from side) appearing acutely hooked, usually projecting above dorsal surface; parameres (viewed from side) strongly triangular, base extending well below lower margin of phallobase as heel-like protuberance. Male cephalic process variable; female bearing trituberculate cephalic carina. South America (one Mesoamerican species).............................................................................................................. 3

3(2). Cephalic horn of large male more-or-less laminate, strongly raised, with apical tubercles or processes, never a trituberculate carina or raised ridge (e.g. Fig. 213, 218, 220, 227). Male head horn (and female carina) set close to eyes so that length of frons along midline usually no more than length of clypeus, often only one-half or less (cf. Fig. 171). Elytral interstriae usually flat or weakly convex, rarely narrowly raised midlongitudinally (C. ignecinctus, Fig. 232). South America, one species Mesoamerican (Fig. 237-238)........................ dardanus species group

— Male and female with trituberculate cephalic carina, position relative to eyes variable (Fig. 287, 289). Elytral interstriae narrowly raised midlongitudinally. Eastern slopes of Andes from Bolivia to Colombia........................................................................................... ohausi species group