Couplet 28

28a:  Prosternum in front of fore coxae longer than intecoxal process; body length < 5 mm; mandible with dorsal setose cavity, covered by clypeus when closed; with or without dorsolbasal tubercle that fits into side of clypeus; dorsally flattened; elytra covered with fine, moderately dense, suberect to erect setae (Psammoecini)

Silvanidae   p. 431

28b:  Prosternum usually shorter than or subequal in length to intercoxal process; if longer, then body length < 7 mm; mandible lacking dorsal setose cavity, and dorsolbasal tubercle; body form and setation variable