Taxa in Extant Turtles

Subclass Anapsida
Order Testudines - Turtles (phylogeny1, phylogeny2)

Suborder Cryptodira

* Family Chelydridae (Snapping Turtles)

Superfamily Testudinoidea

* Family Emydidae (Pond Turtles/Box and Water Turtles)
* Family Testudinidae (Tortoises)
* Family Geoemydidae (Bataguridae) (Asian River Turtles, Leaf and Roofed Turtles, Asian Box Turtles)

Superfamily Trionychoidea

* Family Carettochelyidae (Pignose Turtles)
* Family Trionychidae (Softshell Turtles)

Superfamily Kinosternoidea

* Family Dermatemydidae (River Turtles)
* Family Kinosternidae (Mud and Musk Turtles)

Superfamily Chelonioidea

* Family Cheloniidae (Sea Turtles)
* Family Dermochelyidae (Leatherback Turtles)

Suborder Pleurodira (phylogeny, but see also phylogeny2)

* Family Chelidae (Austro-American Sideneck Turtles)

Superfam. Pelomedusoidea

* Family Pelomedusidae (Afro-American Sideneck Turtles)
* Family Podocnemididae (Madagascan Big-headed and American Sideneck River Turtles)

Family Chelydridae (Snapping Turtles)

Order Testudines
Suborder Cryptodira
Superfamily Testudinoidea

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Family Chelydridae (Snapping Turtles)

The family Chelydridae contains only three species in three monotypic genera.

Chelydra serpentina.

Appearance: Chelydrids are large freshwater turtles with massive heads. Their head is indeed so big that it cannot be retracted fully within the shell. The same is true for their limbs. The carapaces of chelydrids are flattened, triridged, and nearly rectangular in outline, and the plastrons are reduced. The three species have unusually long tails, almost equaling the length of their carapaces.

Size: Macrochelys (formerly Macroclemys) is one of the heaviest freshwater turtles worldwide (max. carapax length 80 cm, max. weight 80 kg).

Distribution: North America (Chelydrinae), China and Indochina (Platysterninae).

Relationships: Platysternon has been considered as a member of the Testudinidae or as a separate family, Platysternidae.

Habitat: Chelydra serpentina inhabits both freshwater and brackish water. Macrochelys lives in rivers, lakes and swamps

Food: Mostly carnivorous (preys include fish, molluscs, worms and other aquatic invertebrates); Chelydra serpentina is an omnivorous species.

Behaviour: Mostly nocturnal foragers. Macrochelys lures fish into its open mouth with a fleshy projection of the tongue that mimics a wormlike prey.

Family Emydidae (Pond Turtles/Box and Water Turtles)

Order Testudines
Suborder Cryptodira
Superfamily Testudinoidea

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Family Emydidae (Pond Turtles/Box and Water Turtles)

Painted Turtle
(Chrysemys picta)

Appearance and morphology: Emydines have oval to oblong and moderately domed carapaces; the plastron is large and occasionally hinged (namely in Emys, Emydoidea, and Terrapene), i.e. they can close their shells to some extent. 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 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. Sexual dimorphism is common and particularly striking in Pseudemys and Graptemys (after Zug et al. 2001).

Size: 8 cm (Clemmys muhlenbergii) to 40 cm (Pseudemys concinna) carapace length. Carapace length of most emydids is less than 20 cm (except for Pseudemys, female Graptemys and Trachemys: in Graptemys adult males are often one-half the size of adult females).

Distribution: Europe to Ural mountains in Russia and adjacent regions; North America southward to northeastern Brazil.

Habitat: Emydines are mainly freshwater or semiaquatic turtles inhabiting marshes, large rivers, and lakes. A few genera are terrestrial (Terrapene except T. coahuila) or even inhabit brackish marshes and coastal marine habitats (Malaclemys terrapin).

Reproduction: Eggs are deposited in spring; hatching occurs later in the summer, usually with a 60 to 80 day incubation period. Hatchlings of some species such as Chrysemys picta, overwinter in the nest in the northern part of their distribution. Clutches contain 2 to 10 eggs on average although Pseudemys and Trachemys may have larger clutches.

Food: Adult emydines are usually omnivorous, but Emydoidea and Deirochelys are primarily carnivorous. Juveniles of almost all species also eat animal prey. Large Pseudemys are strictly herbivorous.

Taxonomic notes: Feldman & Parham (2002) also suggested to synonymize Emydoidea with Emys and to restrict Clemmys to Clemmys marmorata (which we have done in this database, see individual entries for details and references, and tree below for details). Seidel (2002) also suggested a number of changes within this family, especially by raising a number of Trachemys subspecies to species level. Subfamilial classifcation follows Gaffney & Meylan (1988).

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.

Family Trionychidae - Softshell Turtles

Order Testudines
Suborder Cryptodira
Superfamily Trionychoidea

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Family Trionychidae - Softshell Turtles

Content: 2 subfamilies: Cyclanorbinae, Trionychinae, ca. 30 species

Apalone spinifera aspera

Appearance and morphology: Softshells are flattened, pancake-shaped turtles that have reduced bony carapaces and plastrons. The carapace and plastron are naked, lacking epidermal scutes, but are covered with a thick, leathery skin. 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 (?); the flattened carapace lacks peripheral bones (except in Lissemys), and the nuchal lacks 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 has a thelial process (after Zug et al. 2001).

Characteristic differences between the subfamilies:

Cyclanorbinae have a latticelike plastral skeleton with bilaterally fused hyoplastral and hypoplastral bones. Externally the plastron has well-developed femoral flaps. Trionychinae also have a latticelike plastral skeleton but with separate hyoplastral and hypoplastral bones on each side. The plastron lacks femoral flaps.

Size: Cyclanorbinae: 37 cm (Lissemys) to 60 cm (Cyclanorbis elegans) carapace length. Trionychinae: 20 cm (Pelodiscus sinensis) to more than 1 m (Trionyx triunguis, Pelochelys, Chitra); most other genera reach 40 to 60 cm carapace length.

Distribution: Sub-Saharan and northeastern central Africa, South Asia (Cyclanorbinae); Eastern North America, South Asia to Japan and southward to New Guinea, north-central sub-Saharan Africa into Southwest Asia (Trionychinae).

Habitat: All cyclanorbines are probably aquatic bottom-dwellers like trionychines and both live in rivers and lakes. Dogania subplana occurs in small mountain streams

Behavior: Softshells actively forage and also lie partially hidden in the bottom sand or silt, waiting for passing prey. Their long necks and snorkellike snouts permit them to stick their noses to the water surface to breathe. At least trionychines may also depend on cutaneous respiration. Trionychines are actively foraging for prey and they are excellent swimmers.

Reproduction: Lissemys punctata deposits 2 to 14 eggs. Clutch size may vary geographically and at least some females produce multiple clutches per year. Incubation ranges from 30 to 40 days to more than 300 days in some cyclanorbines. Temperate and subtemperate trionychines are predominantly spring breeders and tropical species lay eggs in the early dry season. apalone deposits 4 to 30 eggs per clutch while Pelodiscus sinensis lays 9 to 15 eggs. The large Trionyx triunguis can deposit over 100 eggs but usually produces about 50. Incubation is generally 56 to 70 days, although in Aspideretes gangeticus it lasts 250 to 290 days. The lower record is hold by Pelodiscus sinensis with an incubation period of 28 days.

Food: Cyclanorbinae: invertebrates, small vertebrates, occasionally plants. Trionychinae are predominantly carnivorous although the may eat plant material if animal prey is not available.

Taxonomic note: Wermuth & Mertens (1977) listed 11 species of the genus Trionyx. Ernst & Barbour (1989) split this group in many separate genera. According to Engstrom et al. (2004) Nilssonia is nested within Aspideretes but the former has priority over the latter, i.e. all Aspideretes should be renamed Nilssonia.

Family Dermatemydidae (Mesoamerican River Turtles)

Order Testudines (Turtles)
Suborder Cryptodira (Hidden-necked Turtles)
Superfamily Kinosternoidea

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Family Dermatemydidae (Mesoamerican River Turtles)

This family consists of only one species, Dermatemys mawii.

Dermatemys mawii

Appearance: Oblong, slightly domed carapace, large plastron, moderately small head.

Distribution: Southern Mexico to northern Honduras.

Habitat: Aquatic, in large rivers, lakes, and temporary pools. Occassionally enters brackish water.

Behavior: Mostly nocturnal; foraging occurs at night. Adapted to its aquatic lifestyle, only rarely surfacing. Captive individuals continually take water in through the mouth and expel it from the nostrils (Ernst and Barbour 1989).

Size: up to 65 cm (max. carapace length)

Food: Vegetarian; aquatic plants, fruit and seeds that fall into the water.

Reproduction: oviparous (2-20 eggs per clutch); courtship and mating from May to September, egg depostition from October to December; females nest along rivers. Occassionally nests are submerged but eggs often survive by developmental arrest. Incubation is 8 to 10 months; hatching occurs in June and July with the beginning of the rainy season.

Conservation: The Mesoamerican River turtle is easily captured and serves as a local food item. Now endangered.

Family Kinosternidae - Mud and Musk Turtles

Order Testudines
Suborder Cryptodira
Superfamily Trionychoidea

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Family Kinosternidae - Mud and Musk Turtles

Content: 2 subfamilies: Kinosterninae, Staurotypinae

Scorpion Mud Turtle (Kinosternon scorpiodes)

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.

Family Cheloniidae

Order Testudines
Suborder Cryptodira
Superfamily Chelonioidea
Family Cheloniidae

List of genera:

Subfamily Carettinae

* Caretta
* Lepidochelys

Subfamily Cheloniinae

* Chelonia
* Eretmochelys
* Natator

The subfamilies listed here are not accepted by Zug et al. (2001)

Family Dermochelyidae - Leatherback Seaturtles

Order Testudines
Suborder Cryptodira
Superfamily Chelonioidea

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Family Dermochelyidae - Leatherback Seaturtles

A single species, the Leatherback (Dermochelys coriacea), is the only living member of the family.

Appearance and morphology: The dermochelyds are marine turtles with broad, ridged shells that lack epidermal scutes. The dermal bones of the carapace and plastron are largely replaced by a mosaic of small platelets set in a leathery skin. The limbs are paddle-shaped and without claws: the anterior ones are very large, and the posterior ones of the adults are broadly connected to the tail by a web.

This exraordinary creature can be confused with nothing else. It is distinguished from all other sea turtles by the scaleless black skin of its back and by the seven narrow ridges, formed by enlarged platelets of the dermal mosaic, that extend down the length of its back. Five similar keels occur on the ventral surface. There is a strongly marked cusp on each side of the upper jaw.

Physiological adaptations: The adults wander into temperate and subarctic waters. Their occurence in such cold water was once thought to be accidental, but recent evidence of temperature regulation and body temperatures higher than ambient indicates that they are inertial endotherms (muscle activity generates body heat). The high oil content of the shell would also act as insulation, like blubber on whales.

Size: This largest living turtle may reach a carapace length of 1.7 m and a weight of 680 kg or more, but such giants are rare. The large specimens encountered from time to time along the coasts today probably weigh around 360 kg, about the size of a large Loggerhead.

Distribution: The pelagic Leatherback is widely distributed, though usually scarce, in all tropical seas.

Habitat: Ocean waters.

Behavior: Leatherbacks are remarkably strong and rapid swimmers. They are highly migratory, potentially crossing and recrossing the entire ocean basins.

Reproduction: The nesting of Leatherbacks is confined to tropical beaches. They have a multiyear reproductive cycle, i.e. females return to their nesting beaches biennially or triennially, laying multiple clutches within one nesting season. Clutch sizes range from 40 to 160 eggs (average about 80).

Food: Dermochelys coriacea feeds on crustaceans, mollusks, and small fishes, as well as on marine plants. Jellyfish also appear to be an important food in some areas.

Family Chelidae

Order Testudines
Suborder Pleurodira

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Family Chelidae

Morphology: Chelids are characterized by unusually extensive emargination of the cheekbones so that only a parietal-squamosal bar remains. Quadratojugals and mesoplastra are absent, distinguishing chelids from pelomedusids. Key osteological features: cervical scute present; neurals reduced, 7 or fewer, absent in some; 9 plastral bones, mesoplastra absent; no quadratojugal or temporal arch; prefrontals not in contact; palatals separated by vomer; lower jaw usually slender and weak; neck incompletely retractile; 5th & 6th cervicals amphicoelous, none saddle-shaped; neck typically very long, retracted by 1 or 2 lateral bends; cervical scute usually present, absent in 1 genus;

Size: 15 centimeters in carapace length (Pseudemydura umbrina) to nearly 50 centimeters (Chelodina expansa) .

Distribution: South America, Australia, and New Guinea.

Habitat: Aquatic or semi-aquatic. Most species inhabit slow-moving freshwater or swamps, although Chelodina siebenrocki also occurs in brackish water.

Food: Fish and aquatic invertebrates.

Reproduction: Some populations of Platemys platycephala exhibit an unusual form of triploidy in which individual cells are diploid or triploid within an individual (Bickhamn et al. 1985).

Family Pelomedusidae

Order Testudines
Suborder Pleurodira

Family Pelomedusidae (African Mud Terrapins)

Appearance: African Mud Terrapins usually have oblong, moderately high-domed carapaces, large plastra (hinged in Pelusios, not hinged in Pelomedusa) and moderate-sized heads.


The jaw closure mechanism articulates on a pterygoid trochlear surface that lacks a synovial capsule but contains a fluid-filled saclike duct from the buccal cavity. Both epipterygoid and parietal-squamosal contact is missing in the skull; the internal carotid canal lies in the prootic, and the postorbital has strong contact to the squamosal. The facial nerve has a hyomandibular branch. The plastron has a mesoplastron and well-developed plastral buttresses that articulate with the costals on each side of the carapace; the carapace has 11 pairs of sutured peripherals around its margin and a nuchal without costiform processes. The neck withdraws horizontally, and this mechanism is reflected in an anteriorly oriented articular surface of the first thoracic vertebra; other vertebral traits are the inclusion of the 10th thoracic vertebra in the sacral complex and procoelous caudal vertebrae. The pelvic girdle is firmly fused to the plastron, and the ilium lacks a thelial process. The karyotype is 2N = 34 or 36 (after Zug et al. 2001).

Size: 12 cm (Pelusios nanus) to 46 cm (Pelusios sinuatus) carapace length (adults).

Distribution: Sub-Sharan Africa, Madagascar, Seychelles.

Habitat: Mud terrapins are semiaquatic or aquatic bottom walkers of slow-moving waters (lakes , swamps, marshes etc.).

Food: small animals such as arthropods, worms, etc.

Behaviour: Species in seasonally dry waterways estivate or hibernate in the bottom or on shore immediately adjacent to the drying habitat.

Reproduction: clutches have 6 to 18 eggs, depending on female size. Egg deposition occurs in the more equitable season of the year. Incubation periods range from 8 to 10 weeks.

Relationships: The Pelomedusidae have also been considered as a subfamily Pelomedusinae of a bigger family "Pelomedusidae sensu lato" which included the Podocnemididae as a second subfamily (Podocnemidinae, containing the genera Erymnochelys, Peltocephalus, and Podocnemis). See tree below and the Podocnemididae and Chelidae pages.

Family Podocnemididae

Order Testudines
Suborder Pleurodira

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Family Podocnemididae

Madagascan Big-headed Turtles and American Sideneck River Turtles

Podocnemis unifilis

Appearance: Podocnemidids have broad domed, streamlined shells adapted to swimming.

The jaw closure mechanism articulates on a pterygoid trochlear surface that lacks a synovial capsule but contains a fluid-filled saclike duct from the buccal cavity. Both epipterygoid and parietal-squamosal contacts are missing in the skull; the internal carotid canal lies in the prootic, and the postorbital has strong contact to the squamosal. The facial nerve has a hyomandibular branch. The plastron has a mesoplastron and well-developed plastral buttresses that articulate with the costals on each side of the carapace; the carapace has 11 pairs of sutured peripherals around its margin and a nuchal without costiform processes. The neck withdraws horizontally, and this mechanism is reflected in an anteriorly oriented articular surface of the first thoracic vertebra; other vertebral traits are the inclusion of the 10th thoracic vertebra in the sacral complex and procoelous caudal vertebrae. The pelvic girdle is firmly fused to the plastron, and the ilium lacks a thelial process. The karyotype is 2N = 28 (after Zug et al. 2001).

Size: 20 cm (Podocnemis erythrocephala) to 80 cm (Podocnemis expansa) carapace length (adults).

Distribution: Madagascar, Northern South America.

Habitat: Rivers and other moderate currents.

Food: Mostly plants but occasionally small, slow-moving animal prey and carrion is also eaten.

Reproduction: Nesting takes place on sandy river banks. P. expansa nests in larger groups and each female lays s60 to 120 eggs (smaller species produce smaller clutches). Incubation periods in P. expansa eggs is 42 to 47 days, whereas those of P. vogli require 127 to 149 days.