Staurotypus salvinii, the Pacific Coast giant musk turtle, is a member of Kinosternidae within Cryptodira. Kinosternidae contains three extant genera and several extinct taxa (Bonin et al., 2006). Long thought to be the sister-group to Trionychidae (e.g., Gaffney, 1975), the relationship of this taxon to other turtles has recently been called into question on the basis of both molecular and morphological features (e.g., Shaffer et al., 1997).
Staurotypus salvinii is a moderate-sized turtle whose carapace length may reach 25 cm (Ernst and Barbour, 1989; Bonin et al., 2006). Its skull is large for its body size, and exhibits temporal emargination and a secondary palate (Ernst and Barbour, 1989). The oval carapace exhibits three distinct keels and is not serrated, while the small plastron has a slight hinge. Staurotypus salvinii varies in color from olive gray to dark brown, with yellow or orange markings on the head. Staurotypus salvinii and the other species of Staurotypus, S. triporcatus, are unique among kinosternids in the possession of male sex chromosomes (e.g., Bull et al., 1974; Sites et al., 1979).
Staurotypus salvinii inhabits slow-moving bodies of freshwater with soft bottoms and abundant vegetation, from southern Mexico to El Salvador and Guatemala (Ernst and Barbour, 1989; Bonin et al., 2006). It is carnivorous, feeding on aquatic invertebrates, amphibians, and small fish. Females lay several clutches of six to ten eggs per year. Staurotypus salvinii is aggressive and can deliver a powerful bite (Ernst and Barbour, 1989; Bonin et al., 2006).
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