New information on the evolution of mating behaviour in Sepsidae (Diptera) and the cost of male copulations in Saltella sphondylii

Here we describe the hitherto unknown details of the highly unusual mating behaviour of Saltella sphondylii-a widely cited model for male longevity costs caused by multiple copulations. When compared to the known mating behaviour of 28 sepsid species, we find five unique behavioural elements based on frame-by-frame analyses of video-recordings. These new behaviours are documented with video clips. We suggest that the male longevity costs could be due to copulation bouts that involve multiple insertions of a comparatively membranous phallus into the female. We compare the phallus of the Saltella sphondylii to those from three other species (Themira putris, Parapaleosepsis plebeia, Sepsis punctum).