Baker, P.J.: Ontogenetic changes in plastral callosities of the Senegal flapshell turtle, Cyclanorbis senegalensis

The number and location of the plastral callosities are reliable characters used to distinguish adults of the Senegal flap-shelled turtle, Cyclanorbis senegalensis, from its congener the Nubian flap-shelled turtle, C. elegans. Adult C. senegalensis have seven to nine callosities present on the plastron including five preplastral callosities whereas adult C. elegans have a maximum of four callosities with no preplastral callosities. However, difficulties in identification arise when comparing specimens of different sizes and sexes. After examining a large series of live C. senegalensis, with specimens ranging from juvenile to adult, I have observed that the development of the plastral callosities is determined by both the size and sex of the individual. Females attain a greater carapace length (CL) than males; and thus males develop a full complement of nine callosities at a smaller CL than females. The number, size, and shape of the plastral callosities of C. senegalensis can be used as both a character to distinguish male from female specimens, as well as a diagnostic character to distinguish between species.