Family Geoemydidae (including Geoemydinae and Batagurinae)

Order Testudines
Suborder Cryptodira
Superfamily Testudinoidea

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Family Geoemydidae (including Geoemydinae and Batagurinae)

(Asian River Turtles, Leaf and Roofed Turtles, Asian Box Turtles)

Keeled Box Turtle (Pyxidea mouhotii)
© Wayne van Devender

Appearance and morphology: Turtles with oval to oblong and moderately domed or flattened carapaces; the plastron is large and occasionally hinged. 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 usually articulate firmly with the costals of the carapace; the carapace has 11 pairs of sutured peripherals around its margin and a nuchal without costiform processes. The neck withdraws vertically, and this mechanism is reflected in a 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 vertebra. The pelvic girdle flexibly articulates with the plastron, and the ilium lacks a thelial process (after Zug et al. 2001).

Size: carapax from 13 cm (Geoemyda spengleri, Heosemys silvatica) to 80 cm (Orlitia borneensis).

Distribution: Southern Europe to Japan in Asia, East Asia, Central America and northern South America.

Habitat: mostly aquatic or semiaquatic. Although most species live in freshwater habitats, and a few even in mountain streams (e.g. Cyclemys dentata, Cuora trifasciata) or estuaries (Batagur baska, Callagur borneoensis). Callagur borneoensis is a batagurine that nests on sea beaches along with nesting sea turtles. Geoemyda spengleri , Heosemys silvatica, and Pyxidea mouhotii are terrestrial. However, even within a single genus habitat preferences can vary markedly. For example, Rhinoclemmys has totally terrestrial species (R. annulata) and highly aquatic species (R. annulata)

Reproduction: Most species produce fewer than 10 eggs per clutch, although several appear to ahve multiple clutches during a single season. Geoclemys hamiltoni has 18-30 eggs, Batagur baska on average 20 eggs, Callagur borneoensis 15-25 eggs per clutch. Incubation periods are unknown for most species but appears to be commonly around 3 to 5 months.

Food: Most species are herbivorous (Kachuga smithi), or omnivorous, but some are carnivorous (e.g. Malayemys, Mauremys).

Taxonomic notes: Gaffney & Meylan (1988) state that the Bataguridae would be paraphyletic without the inclusion of the Testudinidae. The generic subdivision into Batagurinae and Geoemydinae follows OBST (2003). Melanochelys, Heosemys are sometimes considered as subgenera of Geoemyda. Annamemys has been synonymized with Mauremys. Cistoclemmys is treated here as a synonym of Cuora. Pyxidea has been synonymized with Cuora by SPINKS e al. (2004) who also included Chinemys in Mauremys and Hieremys in Heosemys. Another change suggested by SPINKS et al. (2004) is the revalidation of Pangshura for several species of Kachuga. Note that according to these authors the subfamilial classification of the Geoemydidae needs to be revised significantly. See the figure below for generic relationships based on DNA sequence data.