Carapace of the African Sideneck turtle Olukole et al. Morphological Analysis of the Carapace of the African Sideneck Turtle (Pelusios castaneus) Olukole S.G.⃰ 1; Okusanya B.O.2; Agbato O.A. 1, Kekere A. D. 1; Oyeyemi M.O. 2; Oke B.O. 1 1Department of Veterinary Anatomy, Faculty of Veterinary Medicine, University of Iba- dan, Ibadan, Nigeria. 2 Department of Veterinary Surgery and Reproduction, Faculty of Veterinary Medicine, University of Ibadan, Ibadan, Nigeria. With 3 figures received in September, accepted for publication September 2013 Abstract marginal scutes with the infra- The morphological analysis of the marginal scute forming the bridge carapace of the African sideneck between the carapace and plastron. turtle (Pelusios castaneus) was car- The turtle had seven neural bones ried out using twenty adult turtles flanked on each side by eight pairs comprising twenty females and forty of pleurals, while eleven pairs of pe- males picked up at different times in ripheral bones surrounded the pleu- various river banks in Ibadan, Nige- rals. The basic anatomy of the shell ria with the view to providing base- of this animal is similar to those of line information that could be useful earlier reports on shell morphology in the comparative osteology of sea of the chelonians. and freshwater turtles as well as in the identification of the shell of the Keywords: Carapace, plastron, turtle in paleontological and archae- morphology, scutes, turtle. ological investigations. The average body weight of the turtles used for Introduction the study was 0.82 ± 0.03kg. The The African sideneck turtle (Pelusi- curved carapace and plastron os castaneus) is a freshwater turtle lengths of the turtles were 26.4 of the family Pelomedusidae, widely ±1.87cm and 19.3 ± 1.13cm, re- distributed in West Africa, occurring spectively. The carapace of the tur- from Guinea and Senegal to north- tles varied from dark brown to dark western Angola (Kirkpatrick, 1995). in colour, had five vertebral, four The P. castaneus is a small to me- pairs of costal and twelve pairs of J. Vet. Anat. 47 Vol 7 No 1, (2014) 47 - 56 Carapace of the African Sideneck turtle Olukole et al. dium in size, with relatively exten- functions especially in adults (Erim various river banks in Ibadan, Nige- The carapace had the following sive plastron that may have a hinge et al., 2006). ria, were used for the study. The scutes: vertebral, costal or lateral, present between the pectoral and animals were kept in artificial ponds marginal and inframarginal. In all abdominal scutes (Olukole et al., A number of research reports on the and were stabilized for 72 hours pri- the turtles studied, the vertebral 2010). The turtle shell has long at- shell morphology of chelonians had or to the investigations carried out. scutes were constantly five in num- tracted the attention of comparative been documented. The shell mor- They were fed with commercial fish ber, flat in structure and medial in anatomists, being comprised of dor- phology of the land tortoise, Testu- pellets ad libitum. Standard body position overlaying the enclosed sal and ventral moieties, termed the do graeca Linnaeus, had been doc- parameters were all determined us- vertebrae of the animals (figure 1). carapace and plastron, respectively umented (Amiranashvili, 2000; Per- ing a Draper® 115 mm vernier cali- In all the turtles studied, the second (Nagashima et al., 2012). ala, 2001; Delfino et al., 2009). Also, per and metric tape. The body and third costal scutes matched up shell morphology had been de- weight of the animals was taken with the seventh marginal scute A conservative life history pattern scribed in the Kemp’s ridley, the with the aid of a Microvar® weighing while the third and fourth costal has enabled chelonians to persist Dermochelys and the Loggerhead balance. The turtles were anaesthe- scutes matched up with the ninth for roughly 200 million years and (Wyneken, 2001) as well as in the tized using ketamine HCl at marginal scute. The first and last inhabit terrestrial, fresh water, and Tropical tortoise chelonoidis den- 25mg/kg body weight intramuscular- pairs of marginal scutes are in con- marine habitats (Frazer, 2000). This ticulate (Manzano, 2009). The plas- ly at the medial aspects of the thigh tact with the first and fifth vertebral long persistence of chelonians is tral morphology of four different muscle and then sacrificed by cervi- scutes while marginals III to X relate partly due to the possession of an subspecies of the Caspian turtle cal decapitation. The preparation of with the costal scutes medially. extremely specialised body wall otherwise known as the striped- skeletons of the animals was ob- The inframarginal scute formed the called the shell comprising discrete neck terrapin (Mauremys caspica) tained through hot water maceration bridge between the carapace and bony and epidermal elements. The had also been reported (Tilman and (Sommer and Anderson, 1974). The plastron in each of the turtles. The turtle shell has been considered a Uwe, 1996). arrangement and number of scutes bony elements of the carapace ob- textbook example of a morphologi- and bony elements of the shell were served on each turtle were the nu- cal novelty (Gilbert et al., 2001). There is scarcity of research infor- then investigated. Anatomical no- chal bone, the neural bones, the Turtles are unique among living tet- mation on the shell morphology of menclature used in the study fol- pleurals, the suprapygal and pygal, rapods in that they possess a box- freshwater turtles of African origin. lowed the reports of Lapparent de the peripheral bones, and fused ver- like shell that is formed by dorsal This study provides the first detailed Broin (2001) and Wyenken (2001). tebrae. The nuchal bone relates and ventral parts (the carapace and osteological description of the cara- with the first peripheral bone lateral- plastron), which together cover most pace of the African sideneck turtle, Results ly and with the first pleural latero- of the body of the animals. The car- which could be helpful in the identi- The average body weight of the tur- caudally on both sides of the apace and plastron are of neural fication of the turtle in paleontologi- tles used for the study was 0.82 ± midseam of the plastron. Caudal to crest origin (Clark et al., 2001), de- cal and archaeological remains as 0.03 kg. The curved carapace and the nuchal bone were the neural riving from vertebral and rib ele- well as in the comparative osteology plastron lengths were 26.4 ± 1.87cm bones, seven in number. The mid- ments and lying superficial to both of sea and freshwater turtles. and 19.3 ± 1.13cm, respectively. longitudinal series of neural ele- limb girdles (Burke, 1989). The tur- The carapaces of the turtles used ments were flanked on each side by tle shell provides a significant Material and methods for the study were broadly oval cau- a lateral costal series (pleurals), measure of protection from preda- A total of 20 adult African sideneck dally but blunt cranially; varying while a peripheral set of bones sur- tion and is involved in locomotory turtles picked up at different times in from dark brown to dark in colour. round the pleurals (Figure 2). The J. Vet. Anat. 48 Vol 7 No 1, (2014) 47 - 56 Carapace of the African Sideneck turtle Olukole et al. dium in size, with relatively exten- functions especially in adults (Erim various river banks in Ibadan, Nige- The carapace had the following sive plastron that may have a hinge et al., 2006). ria, were used for the study. The scutes: vertebral, costal or lateral, present between the pectoral and animals were kept in artificial ponds marginal and inframarginal. In all abdominal scutes (Olukole et al., A number of research reports on the and were stabilized for 72 hours pri- the turtles studied, the vertebral 2010). The turtle shell has long at- shell morphology of chelonians had or to the investigations carried out. scutes were constantly five in num- tracted the attention of comparative been documented. The shell mor- They were fed with commercial fish ber, flat in structure and medial in anatomists, being comprised of dor- phology of the land tortoise, Testu- pellets ad libitum. Standard body position overlaying the enclosed sal and ventral moieties, termed the do graeca Linnaeus, had been doc- parameters were all determined us- vertebrae of the animals (figure 1). carapace and plastron, respectively umented (Amiranashvili, 2000; Per- ing a Draper® 115 mm vernier cali- In all the turtles studied, the second (Nagashima et al., 2012). ala, 2001; Delfino et al., 2009). Also, per and metric tape. The body and third costal scutes matched up shell morphology had been de- weight of the animals was taken with the seventh marginal scute A conservative life history pattern scribed in the Kemp’s ridley, the with the aid of a Microvar® weighing while the third and fourth costal has enabled chelonians to persist Dermochelys and the Loggerhead balance. The turtles were anaesthe- scutes matched up with the ninth for roughly 200 million years and (Wyneken, 2001) as well as in the tized using ketamine HCl at marginal scute. The first and last inhabit terrestrial, fresh water, and Tropical tortoise chelonoidis den- 25mg/kg body weight intramuscular- pairs of marginal scutes are in con- marine habitats (Frazer, 2000). This ticulate (Manzano, 2009). The plas- ly at the medial aspects of the thigh tact with the first and fifth vertebral long persistence of chelonians is tral morphology of four different muscle and then sacrificed by cervi- scutes while marginals III to X relate partly due to the possession of an subspecies of the Caspian turtle cal decapitation.