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).