Ecdysis and other aspects of metamorphosis in rove beetles with exarate or obtect pupae (Coleoptera: Staphylinidae)

Abstract

Based on actual observations of ecdysis or examination of exuviae of early- and (or) last-instar larvae of species in the Staphylininae (sensu latu), Paederinae, Steninae, Tachyporinae, Oxytelinae, Omaliinae, and Aleocharinae, it is shown that ecdysis from one larval instar to the next and larval–pupal ecdysis occur in about the same manner in all of these subfamilies. Newly emerged pupae of all Staphylinidae are exarate; pupae of the subfamily Staphylininae then become obtect. These findings refute a previous claim that larval–pupal ecdysis occurs differently in the Staphylininae and Paederinae than in other Staphylinidae. Larvae of Staphylininae and Paederinae have divided abdominal terga and sterna; this might facilitate ecdysis, but not as previously thought. The emerging larva or pupa remains connected to the old larval cuticle by the everted lining of the old larval foregut until near the end of ecdysis; this could be a necessary feature of ecdysis in Staphylinidae. Pupal chaetotaxy could affect how active the pupa is when disturbed.