Couplet 105

105a:  Suture between 2 basal ventrites distinct medially; mid tarsus with small, bisetose empodium; antenna filiform to distinctly clubbed; body strongly convex

Byrrhidae   p. 417

105b:  Suture between 2 basal ventrites weak to absent medially (Figure 26-8B); mid tarsus lacking visible empodium; antenna usually serrate, pectinate, or flabellate; body weakly flattened dorsoventrally