Couplet 107

107a:  Mentum strongly sclerotized, expanded, covering labium and maxillae; head not deflexible; antenna covered by fore legs in broad sternopleural pocket; ventrites 1 and 2 excavate for hind leg; mid tibia with marginal spines; length 4-9 mm

Nosodendridae   p. 424

107b:  Mentum normal, head usually retractable into pronotum to anterior margin of eyes (1 exception); antenna received in internal pronotal cavity beneath head, external anterior pronotal cavity or partly in sternopleural grooves and partly under legs against hypomeron; excavation for hind leg, if present, limited to ventrite 1; margin of mid tibia not spinose; length 1-2mm