MATE-GUARDING, MATING SUCCESS AND BODY-SIZE IN THE TROPICAL MILLIPEDENYSSODESMUS PYTHON (PETERS) (POLYDESMIDA, PLATYRHACIDAE)

Males of the neotropical millipede Nyssodesmus python guard females fo r up to several days following copulation. The majority of the adult p opulation (69%) was found in a mated (guarding) pair at any given time . The sex ratio of solitary individuals was 6:7 (females:males). Body sizes of paired and solitary individuals did not differ for either sex , suggesting that mating success does not depend strongly on body size . Females were larger than males. Body sizes of paired females and mal es were positively correlated (r = 0.22). Laboratory experiments showe d that solitary individuals are receptive to mating. We discuss these observations in light of theory about the evolution of mate-guarding b ehavior.