Centrobolus size dimorphism breaks Rensch’s rule

Abstract

This present research aims to study the relative sexual size dimorphism of Centrobolus (Cook) in 18 congenerics. Millipedes illustrated reversed sexual size dimorphism (SSD) where females were larger than males; and broke Rensch's rule as this dimorphism increased with body size. SSD was calculated in 18 species of the genus Centrobolus and illustrated was regressions; male versus female SSD and SSD vs body size. An allometric equation for Centrobolus was (1) ?=0.00051x-0.01071. SSD ranged from 0.63-2.89 (1.55±0.63; n not less than 18) and was not negatively correlated (R=0.70485; P=0.00109; n=18 spp.) with volume ranging from 284-2683 mm3 (1097.89±638.06; 18). The rejection of the rule appears consistent among arthropods.

Keywords

• dimorphism
• millipede
• SSD
• size