Annelida - Oligochaeta - Lumbricidae - Earthworm (Lumbricus terrestris). Clitellum. Oligochaeta highly specialized reproduction biology includes both asexual - schizogenesis - and sexual modes. Sexual reproduction is hermaphroditic. Mating is by genital contact at clitellum areas and enables mutual exchange of eggs and sperm. Eggs are fertilized in clitellum-secreted cocoons