Reptiles Database

Order Testudines
Suborder Cryptodira
Superfamily Trionychoidea

Family Kinosternidae - Mud and Musk Turtles


Content: 2 subfamilies: Kinosterninae, Staurotypinae

Scorpion Mud Turtle (Kinosternon scorpiodes)
© Wayne van Devender

Appearance and morphology: Kinosternids have oval to oblong and moderately domed carapaces; and moderate to large heads. The plastron is commonly hinged and has 11 or fewer ecpidermal scutes. The jaw closure mechanism articulates on a trochlear surface of the otic capsule and is enclosed in a synovial capsule. An epipterygoid is present in the skull; the internal carotid canal lies in the pterygoid, and the parietal but not the postorbital touches the squamosal. The facial nerve lacks a hyomandibular branch. The plastron lacks a mesoplastron, and the plastral buttresses do not form interdigitating articulations with the costals of the carapace; the carapace has 10 pairs of sutured peripherals around its margin and a nuchal without costiform processes. The neck withdraws vertically, and this mechanism is reflected in an anteroventrally oriented articular surface of the first thoracic vertebra; other vertebral traits are the exclusion of the 10th thoracic vertebra from the sacral complex and procoelous caudal vertebrae. The pelvic girdle flexibly articulates with the plastron, and the ilium lacks a thelial process (after Zug et al. 2001).

Staurotypines have a plastron with an entoplastral bone, and their plastron is either moderately reduced with a hinge (Staurotypus) or strongly reduced (cruciform) without a hinge (Claudius). Kinosternines have a well-developed plastron without an entoplastral bone and the plastron is usually hinged.

Size: Kinosterninae: 8 cm (Sternotherus depressus) to 27 cm (Kinosternon scorpioides) carapace length. Most adults have a maximum adult shell length of less than 18 cm. Staurotypinae: 9 cm (Claudius angustatus) to 38 cm (Staurotypus triporcatus) carapace length.

Distribution: Kinosterninae: Eastern north America southwards to the Amazon in South America. Staurotypinae: Caribbean, Gulf of Mexico, Pacific drainages of Mesoamerica.

Habitat: Kinosternines are aquatic inhabiting pools, marshes, swamps, large rivers, and lakes. Staurotypinae: Claudius angustatus lives in seasonally flooded marshes or pastures. Staurotypus species inhabit slow- or fast-flowing waters and rarely occur in ephemeral waters.

Behavior: Kinosternines are all bottom-walkers and poor swimmers. They forage and mate in water although some hibernate on land and some tropical species forage on land during wet weather. Staurotypinae: Claudius angustatus appears to be active only during the rainy season (June - February).

Reproduction: Kinosternines have small clutch sizes (1 to 4 eggs) although larger taxa may lay up to 16 eggs per clutch. Incubation takes 100 to 150 days. Staurotypinae: Claudius angustatus nests at the end of the wet season (November - February) and then deposits 1 to 5 eggs beneath vegetation. Incubation in captivity has been reported to last 100 to 200 days. Staurotypus has clutches of 3 to 10 eggs.

Food: Kinosternines are omnivorous to carnivorous; they eat mostly aquatic invertebrates, small vertebrates, and carrion. Sternotherus is a molluscivore and has adapted to this particular food by developing big heads with strong jaw muscles.Staurotypines are carnivourous, feeding on aquatic invertebrates and small vertebrates. Staurotypus triporcatus eats mostly snails.

Taxonomic note: Seidel et al. placed Sternotherus in the synonymy of Kinosternon.

List of genera:

Subfamily Kinosterninae

Subfamily Staurotypinae

References:

Ernst,C.H. & Barbour,R.W. (1989)
Turtles of the World
Smithsonian Institution Press, Washington D.C. - London

Iverson, J.B., & Iverson, S.A. 1980
A bibliography to the mud and musk turtle family Kinosternidae.
Smithson. Herpet. Inform. Serv. (48): 73 pp.

Iverson, J. B. 1991
Phylogenetic hypothesis for the evolution of modern Kinosternine turtles.
Herpetological Monographs 5: 1-27

Iverson, John B. 1998
Molecules, morphology, and mud turtle phylogenetics (Family Kinosternidae).
Chelonian Conservation and Biology 3 (1): 113-117

Schilde, M. 2001
Schlammschildkröten: Kinosternon, Sternotherus, Claudius, Staurotypus.
Natur und Tier Verlag, Münster, 136 pp.

Schilde, M. (2004)
Die Moschusschildkröte (Sternotherus odoratus).
Natur und Tier Verlag (Münster), 64 pp.

Seidel,M.E., Iverson,J.B., & Adkins,M.D. (1986)
Biochemical comparisons and phylogenetic relationships in the family Kinosternidae (Testudines)
Copeia 1986: 285-294

Zug,G.R.; Vitt, L.J. & Caldwell, J.P. (2001)
Herpetology, 2nd ed.
Academic Press San Diego, London, [...]XIV + 630 pp.