A quantitative analysis of the marked asymmetry existing between some muscle partners in the pelvic girdle of southern African species of the genus Mabuya (Reptilia: Scincidae)

The pelvic girdle musculature of eleven of the eighteen southern African Mabuya species described by Branch (1988) was examined, using differences in mass to emphasize the marked asymmetry existing between partners of certain muscle pairs. The lighter muscles expressed as indices of their heavier partners gave a mean value of 0,38 (n= 27) with a range of 0,11 to 0,75. The mean value obtained for a symmetrical control pair was 0,95 (n = 27) with a range of 0,90 to 0,99. The arrangement of the asymmetric pairs was the same for all the species, irrespective of sex. The partners of a pair differed in size and the manner in which they originated on the pelvic girdle but showed agreement as far as their insertion on the head of the femur was concerned.