Ecomorphological radiation of Himalayan Northeastern Indian Steninae beetles (Coleoptera, Staphylinidae)

• Applicant: Professor Dr. Oliver Betz
• Subject Area: Systematics and Morphology (Zoology) ; Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 540798085

This project, which lies within the framework of an international German-Indian Collaboration studying the biodiversity of Steninae (Coleoptera, Staphylinidae) across two elevational gradients in Northeast India (Arunachal Pradesh), will investigate aspects of the ecomorphological radiation of this megadiverse clade of rove beetles. Comprising more than 3000 described species, the genus Stenus currently forms the most speciose animal genus on earth. The adults are epigeic, optically oriented predators of springtails and other small arthropods. The most intriguing autapomorphy defining the genus Stenus is a rod-like protrudable elongated labium, with the “paraglossae” at its tip being modified into adhesive pads. This prey-capture apparatus can be protruded towards potential prey in a catapult-like fashion. In the genus Dianous, probably forming a subgenus within Stenus, the labium is not elongated and does not possess a protrudable adhesive prey-capture apparatus. Major objectives to be addressed in this bilateral research project relate to (1) diversity, distributional and niche patterns (habitat, elevation, temperature) along two elevational gradients, (2) morphological and experimental analyses of the function and performance of the mouthparts, the tarsal attachment systems and the potential sensory trade-off between the visual and antennal systems, (3) phylogeny-informed macroevolutionary downstream analyses of relevant morphological, behavioural and ecological traits and their evolutionary radiation and (4) potential assembly rules (e.g. because of environmental filtering or interspecific competition) at the community level. These assembly rules will be determined on the basis of the distribution of ecomorphological traits and the phylogenetic relationships among community members in comparison with random communities based on null models. The project involves a four-month stay in the Indian state of Arunachal Pradesh for the standardized collection of beetles across elevational gradients of two Himalayan foothill mountain ranges and the experimental investigation of both their predatory and tarsal attachment performance in the laboratory at Rajiv Gandhi University. Based on a molecular phylogeny, these data will then be correlated with morphometric measurements to determine the causal relationship between morphology, performance, and ecology. Concatenation of the data matrices of this project with the ecomorphological data generated by the proposer from two distinct mountain regions in Thailand plus that of Central European fauna will allow generalized conclusions to be drawn on the assumption that niche divergence might have been convergently repeated in independently settled (disjunct) zoogeographic regions and resulted in similar ecomorphs and community assemblages. This will support the hypothesis that the evolution of Steninae can be understood from the perspectives of reticulate adaptive and iterative convergent radiation.

• DFG Programme: Research Grants