The vietnamensis species group

Diagnostic characteristics. Large sized, antennae extending beyond shoulders of elytra, ligula strongly dilated at apex, 12-setose, elytra slightly and obliquely truncate at apex, inner apical angle small but distinctly denticulate, outer apical angle broad, striae deep, intervals convex; middle tibia not dilated medially in male; fore and middle tarsi much thicker than hind ones; apical tibial spurs short and sword-like.

Only one species is contained in this group: Hexachaetus vietnamensis n. sp. from Vietnam.