Analysis of intraspecific colour variation in the fossorial Coastal Legless Lizard, Microacontias litoralis (Scincidae: Acontiinae)

Abstract

An analysis of intraspecific variation in the fossorial skink Microacontias litoralis revealed that orange‐coloured and melanistic individuals co‐occur at several localities. Body colour was found to be independent of sex and body size. Both orange‐coloured and melanistic in situ embryos were present in pregnant females, showing that colour polymorphism is not the result of ontogenetic changes induced by environmental conditions, but rather has a genetic basis. The presence of orange‐coloured embryos in melanistic females and vice‐versa shows that breeding in these two colour morphs is not isolated. The functional significance of colour polymorphism in M. litoralis remains unclear, but intraspecific communication or background colour matching as possible selective advantages of melanism are ruled out. Microacontias litoralis is endemic to the west coast of South Africa where there is in general a high incidence of melanistic lizard species and populations associated with zones of upwelling of cold water in the Atlantic Ocean. That the melanistic morph may represent past or present selection for thermal melanism can not be ruled out and further investigation is required.