Dining on diplopods: remarkable feeding behaviour in chlamydephorid slugs (Mollusca: Gastropoda)

Abstract

The diet of southern African carnivorous slugs of the endemic family Chlamydephoridae is discussed. At least three species, Chlamydephorus bruggeni, C. burnupi and C. sexangulus, are predators of pill-millipedes Sphaerotherium sp. The feeding behaviour of C. sexangulus is described in detail and illustrated. It is suggested that the prey, once captured, is killed or immobilized by the introduction of a toxin through the intersegmental membrane joining the millipede's skeletal plates. The source for such a toxin may be the anterior pedal mucous gland. Predation on sphaerotheriid millipedes may be a behavioural apomorphy associated with a clade within the Chlamydephoridae, including taxa with longitudinal body keels and distinctive radula morphology, but it is evidently not confined to this clade. Whether the diet of such millipede-eating slugs is limited to millipedes is unknown, but it is probable that at least some chlamydephorids feed on more conventional prey such as snails and earthworms.