SEM illustrations of structural features of mandibles of Geocharidius species. A–B G. zullinii: dorsal aspect of left and right mandibles, respectively C–D G. jalapensis: dorsal aspect of left and right mandibles, respectively E–F G. zullinii:–ventral aspect of left and right mandibles, respectively G–H G. jalapensis: ventral aspect of left and right mandibles, respectively (right mandible with Λ-shaped crack apically from retinacular ridge). Legend: art – anterior retinacular tooth; bemr – molar ridge, basal extension; it – incisor tooth; mr – molar ridge; mt – molar tooth; pog – posterior occlusal grove; prt – posterior retinacular tooth; rr – retinacular ridge; tr – terebral ridge; tt – terebral tooth; vg – ventral groove; vm – microtrichia. Scale = 0.05mm.