Development of the adult abdominal defensive gland in Atheta coriaria Kraatz: a key innovation for ecological and biological success (Coleoptera: Staphylinidae: Aleocharinae)

In Staphylinidae, the presence of an abdominal defensive gland in adults and larvae is hypothesized to be a novel structure supporting the monophyly of a diverse clade coined the “higher Aleocharinae.” Aleocharinae is the most diverse subfamily of rove beetles with close to 16,000 described species. Over 95% of this diversity is found within the “higher Aleocharinae,” and earlier diverging lineages lack this unique abdominal gland, leading previous workers to hypothesize that the abdominal gland has influenced “higher Aleocharinae” diversification. Indeed, glandular chemistry is diverse across taxa, and compounds have been shown to reflect life history strategies. The gland is especially pronounced in groups that are symbionts of ant and termite colonies, and may have served as a pre-adaptation to the subfamily’s propensity to repeatedly evolve this unusual ecology. Here we describe the development of the adult abdominal defensive gland in a representative “higher aleocharine.” For this study, we chose to use Atheta coriaria Kraatz as a model, a species known for its use as a biological control agent in greenhouse settings. We additionally present properties demonstrated by A. coriaria that suggests the species’ potential as a future model organism.