Sexual Pelvic Bone Dimorphism in the West African Fruit Bat, Epomops franqueti

Abstract

Patterns of sexual pelvic bone dimorphism in mammals are well documented. However, limited osteo-morphometrical examinations exist of the nature of dimorphism in the bony pelvis of the bat. This study, therefore, investigated the patterns of size and shape dimorphism in the pelvic bone of the West African fruit bat, Epomops franqueti, using landmark-based osteo-morphometric and non-metric techniques. The interpubic space was closed in the male but open in the female on palpation. Grossly, a synostosis was observed between the medial ends of the pubic bone in the male instead of a symphysis, joined by interpubic ligament, in the female. The shape of the pelvic outlet was ring-like in the male but triangular in the female. The lengths of the ilium, pubis, ossa coxarum as well as the diagonal and transverse diameters of the pelvic inlet were each significantly larger (p<0.05) in the male than in the female. The interacetabular space and the transverse diameter of the pelvic outlet were significantly shorter (p<0.001) in the male than those of the female. The observation of sexual dimorphism in the length of the ilium and the synostosis at the medial ends of the pubic bone of the male in Epomops franqueti differentiates this fruit bat from the Eidolon helvum and the Epomops buettikoferi, respectively.

Keywords: Sexual dimorphism, Morphology, Pelvis, Bat, Epomops franqueti