Family Testudinidae (Tortoises)

Order Testudines
Suborder Cryptodira
Superfamily Testudinoidea

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Family Testudinidae (Tortoises)

Geochelone denticulata.

Appearance: They have high domed shells and stout, heavily scaled limbs (Malacochersus is an exception with a dorsoventrally compressed shell). The head and limbs can be fully withdrawn into the shell. The genera Testudo and Pyxis have hinged plastrons while members of the genus Kinyxis have, uniquely among tortoises, a hinged carapace that allows it to be lowered over the hindquarters.

Size: 10 - 125 cm carapax length. Gigantism has evolved independently in several island populations, with those of the Galapagos and Aldabra islands being the most famous.

Distribution: Testudinids are land turtles that occur mainly in Africa in Asia although a few species are known from the Americas and Europe.

Food: predominantly herbivorous or omnivorous

Habitat: Tortoises are mainly arid-adapted.

Behaviour: Juvenile turtles tend to be cryptic, because their shell doesn't protect them from predators yet.

Reproduction: About 12 eggs in Testudo graeca and Testudo (= Agrionemys) horsfieldii. the latter deposits its eggs in July and the young hatch only 9 months later (April). In contrast, the young of Testudo kleinmanni hatch already after 20 days.

Relationships: Sometimes the Batagurinae have been included as subfamily in the Testudinidae, although they are also dconsidered as separate family, Bataguridae, or as subfamily of the Emydidae.

Taxonomic notes: Geochelone is considered as a subgenus of Testudo by Wermuth & Mertens (1977), but as a valid genus by Ernst & Barbour (1989). The species list given bellow follows mainly Ernst & Barbour (1989).

Geochelone, Asterochelys, Chelonoidis, Megalochelys, and Testudo are used synonymously to some extent. Check species list of Geochelone and Testudo. The giant tortoises of Galapagos (Geochelone elephantopus ssp.) have been subdivided in a series of separate species. The Indian Ocean giant tortoises (genus Cylindraspis) seem to be extinct now (Arnold 1979, Bour 1980). Cylindraspis contains at least 5 species: borbonica (Réunion), triserrata, inepta (both Mauritius), vosmaeri, peltastes (both Rodrigues) (AUSTIN et al. 2002).

Subgenera of Testudo according to Wermuth & Mertens (1977): Acinixys, Agrionemys, Asterochelys, Chelonoidis, Chersina, Geochelone, Indotestudo, Manouria, Megalochelys, Psammobates, Pseudotestudo, Testudo.

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.

Family Carettochelyidae (Pignose Turtles)

Order Testudines (Turtles)
Suborder Cryptodira (hidden- or S-necks)
Superfamily Trionychoidea

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Family Carettochelyidae (Pignose Turtles)

Only one species belongs to this family, the pig-nosed turtle, Carettochelys insculpta.

Appearance: Forelimbs flipperlike, shell ovoid, high-domed, and covered by

a heavy, rugose skin. The head ends in a thick, snorkellike snout (name!).

Distribution: Southern New Guinea and northern Australia.

Habitat: aquatic: rivers, lakes

Size: 55 cm carapax length (max.)

Food: omnivorous but seems to prefer plant matter like fruit, seeds, roots, leaves etc.