The vietnamensis group:

27(3). Eight rows of gibbosities (VIII:2-2-2-2-2-2-2-2), eyes absent........................................... D. minimus -. More than eight rows of gibbosities, eyes present........................................................... 28 28(27). Nine rows of gibbosities (IX:5-4-5-4-5-4-5-2-3), dorsal cuticle with fine granulation.................... D. vietnamensis -. More than nine rows of gibbosities, cuticle with polygonal tubercles............................................29 29(28). Ten rows of well visible gibbosities (X:4-4-4-4-4-4-4-2-2-3)............................................ D. gibber -. More than ten rows of gibbosities........................................................................30 30(29). Twelve rows of poorly visible gibbosities (XII:2-4-2-4-2-4-2-4-2-4-4-1)................................. D. mariae -. Sixteen rows of dorso-lateral gibbosities present (XVI: 3-4-2-6-2-6-2-6-2-6-6-2-6-2-3-3+2[LII-IV])......... D. elleneddiei