Couplet 18

18a:  Abdomen with 7 ventrites, the first divided by hind coxa; head strongly constricted behind eyes; fore tibia with 1 or 2 apical spurs; trochantin exposed; mid coxa conical and projecting; length 5-9 mm

Diphyllostomatidae   p. 411

18b:  Abdomen with 5-6 ventrites, the first not divided; head not strongly constricted behind eyes; fore tibia lacking apical spurs; trochantin not visible; mid coxa not projecting; length 8-60 mm