Mouthpart Ecomorphology and Predatory Behaviour in Selected Rove Beetles of the “Staphylinine Group” (Coleoptera: Staphylinidae: Staphylininae, Paederinae)

SIMPLE SUMMARY: An understanding of the evolution and diversity of organisms is vital not only in its own right, but also with regard to the way that ecosystems function and can be protected. We explore the mouthpart morphology, the feeding behaviour, and the predatory performance of several species within the hyperdiverse family of rove beetles (Staphylinidae, subfamilies Paederinae and Staphylininae) and the connections between these aspects by using scanning electron microscopy of dissected mouthparts and front legs and highspeed videography of prey-capture behaviour. Our behavioural and morphological findings indicate that the investigated representatives of the Paederinae are specialized on elusive prey such as springtails (Collembola), whereas the observed Staphylininae display characteristics more associated with generalist predation. The detected shape differences of the mandibles between the representatives of the two analysed subfamilies are correlated with predatory performance on specific types of prey. We also found correlations between body size and the preferred prey type. We describe several methods of prey capture: beetles use their front legs to attack their prey, to lift it off the ground, or to cage it. Such strategies differ among species and situations. Overall, this exploratory study provides valuable insights into the links between the morphology, behaviour, and predatory performance of rove beetles. ABSTRACT: The representatives of the megadiverse rove beetle subfamilies Paederinae and Staphylininae (Coleoptera: Staphylinidae) are considered generalist predators, although their exact prey-capture behaviour and performance and possible links to mouthpart morphology have rarely been described. Here, we examine these relationships for selected species by SEM analyses of mouthparts and front legs and highspeed videography of prey-capture behaviour. We describe the observed behaviours and structural properties and quantify relationships between prey type, mouthpart morphology, and predatory performance based on morphometric measurements of both the shape and lever properties of the mandible. We show that the Staphylininae considered have morphological and behavioural properties generally associated with generalist predation and that the Paederinae considered display characteristics that are highly specialized on elusive prey such as Collembola. We found correlations between mandible shape and leverage, and body size and prey type. We report distinct prey-capture behaviours: the beetles use front legs and/or mandibles to attack prey, drag prey, or cage it between their legs. These strategies differ among species and situations. Overall, this exploratory study provides insights into the morphology and types of prey capture that must have played a major role in the evolution of these beetles.