Couplet 101

101a:  Metasternite with postcoxal lines delimiting retractile position of mid tibia; antenna hidden in subocular groove and cavity between head and pronotum; body oval

Lutrochidae   p. 420

101b:  Metasternite without postcoxal lines; subocular groove absent or very weakly developed, antenna not hidden in pronotum; body nearly parallel-sided (Figure 26-43B)