Relative sexual size dimorphism in Centrobolus fulgidus (Lawrence) compared to 18 congenerics

Abstract

The present research was aimed to study relative sexual size dimorphism of Centrobolus fulgidus (Lawrence) compared to 18 congenerics. Millipedes illustrate reversed sexual size dimorphism (SSD) as females are larger than males; and corroborate Rensch’s rule as this dimorphism increases with body size. SSD was calculated in 18 species of the genus Centrobolus and illustrated as a regression. The approximate relative position of C. fulgidus was shown from measurements taken at Richards Bay Minerals (February 1996) and St. Lucia Estuary (December 1996) in South Africa. The size of C. fulgidus was 56.2 X 5.4 mm: 63.5 X 5.2 mm (males: females; n=11) and logged (x = 3.398; y = 3.301). The mean volume ratio for C. fulgidus was 1.2505. The evidence suggests the proximate cause for SSD in C. ruber is sexual bimaturism while the ultimate cause in Centrobolus is intersexual competition.