Sexual dimorphism and geographic variation in the morphology of a small southern African tortoise Psammobates oculifer

Toby Keswick, Margaretha D. Hofmeyr
2015 Amphibia-Reptilia  
Supplementary Material Materials and methods We collected data from 146 dead (dry shells and alcohol-preserved [wet] specimens of the Iziko Museum, Cape Town and the Ditsong National Museum of Natural History, Tshane) and 173 live Psammobates oculifer for this study. Data for live individuals were obtained while studying the species' ecology from March 2006 to April 2007 at Benfontein farm (28°53' S; 24°51' E), near Kimberley, South Africa. We counted the number of carapacial, plastral,
more » ... , plastral, axillary and inguinal scutes, noted the position of the latter two scutes relative to adjacent plastral and marginal scutes, and recorded the number and strength (none, weak, medium or strong) of serrated marginal scutes. We also recorded the presence or absence of a plastral concavity, rated the concavity as weak or strong, and noted its position relative to abdominal scutes. Furthermore, we noted the presence and intensity (weak, moderate or strong) of a marginal groove (indentation between pleural and marginal scutes) and bridge ridge (edge alongside of shell) and the associated marginal scute numbers. We could not collect a full set of data for each individual because some museum specimens were damaged whereas time constraints during peak activity periods did not allow detailed measurements of all live individuals. In order to evaluate shell colouration, we photographed the carapace and plastron of each tortoise with a Panasonic DMC-FZ30 digital camera. In this species, darkbrown to black pigmented rays overlay a yellow to brown shell base colour and we evaluated base colour gradations and estimated the amount of dark pigmentation in 10% increments for both the carapace and plastron. When evaluating pigmentation data, we simplified data by using four categories and not 10% intervals. Category 1 (0%, 10%, and 20%; supplementary fig. S1a) included three
doi:10.1163/15685381-00002976 fatcat:zrir6qec4jdqnlt6n73w3lefqe