The Vertebral Formula of the African Sideneck Turtle (Pelusios castaneus)

Abstract

An osteological analysis of the vertebral column of the African sideneck turtle (Pelusios castaneus), was carried out with the view of deriving its vertebral formula which could be useful in the comparative systematic anatomy of sea and freshwater turtles as well as in paleontological and archaeological investigations. A total of sixty five adult African sideneck turtles comprising twenty five females and forty males picked up at different times in various river banks in Ibadan, Nigeria, were used for the study. The average body weight of the turtles used for the study was 0.82 ±0.03kg. The curved carapace and plastron lengths of the turtles were 26-4 ±1.87cm and 19.3 ± 1.13cm, respectively. The turtle has eight cervical vertebrae of which the first seven (craniocaudally) were mobile and the last fused with the ventral surface of the carapace and articulated caudally with the first thoracic vertebra. The thoracic vertebrae were seven in number, the last thoracic vertebra articulated with the first sacral vertebra. Three sacral vertebrae were identified in the animals while 15 caudal vertebrae were constantly encountered in all the turtles. The vertebral column of the African side neck turtle consists of 33 vertebrae and its formula can be expressed as C8T7S3Cd15. This formula, the first of its kind in literature is therefore named as the African sideneck turtle vertebral formula (of Olukole) and therefore serves as baseline information on the vertebral column of the turtle.

KEY WORD: Anatomy; Carapace; Freshwater Turtle; Skeletal System; Vertebral Column.