Turtles - Chelonians

Australo-American Sidenecks — Family Chelidae

The Australo-American Sideneck Turtles of the family Chelidae are one of two living families of the turtle suborder Pleurodira. The family is Gondwanan in origin with 15 genera and 52 species Chelids withdraw their necks sideways into the shell. All are highly aquatic with webbed feet and the capacity to stay submerged for long periods of time. The Matamata, Chelus fimbriatus, is a suction feeder that forages for fish. The skull and hyoid apparatus combine with the musculature to produce an enormous suction to literally inhale prey. Chelus is thought to be present on Trinidad – if only as waifs from the Orinoco. The species confirmed present on Trinidad is Mesoclemmys gibba, a turtle of forest streams and ponds.

Mata Mata Turtle, Chelus fimbriatus

Gibba Turtle, Mesoclemmys gibba 

Afro-American Sidenecks — Family Pelomedusidae

The Afro-American sideneck turtle family Pelomedusidae holds about 26 species in five genera. They occur in South America, Africa, Madagascar, and the Seychelles. Pelomedusidae range in size from 12 to 107 cm in carapace length. Pelomedusids are diagnosed by the lack of a cervical scute, nasal bone, and splenial bone, as well as the shapes of the cervical vertebrae. Like the Chelids, they cannot completely withdraw their head and neck into the shell. These species also have a carapace that flares outward posteriorly. They are aquatic and use freshwater habitats that range from temporary ponds, large rivers, and swamps. Most members of the family are carnivorous with diets including mollusks, crustaceans, aquatic insects, fishes, and amphibians; while others are omnivorous, feeding on aquatic vegetation including fruits. Clutch size is highly variable with females producing as few as six or as many as 100 eggs per clutch; may species produce multiple clutches in a single season. The two families of sideneck turtles shared a common ancestor about 124 mya. There are no extant populations of these turtles on Trinidad or Tobago, but two species may occur as waifs, and may have been present in prehistorical time.

Arrau Sideneck, Podocnemis expansa

Yellow-headed Sideneck, Podocnemis unifilis 

Sea Turtles — Family Cheloniidae

The hard-shelled sea turtle, family Cheloniidae, contains seven species in five genera. They occur worldwide in all tropical oceans and are completely marine, with females coming ashore only to nest. Cheloniids are large turtles, ranging between the 71 cm Olive Ridley, Lepidochelys olivacea, to the 213 cm Loggerhead, Caretta caretta. The shell is oval or heart-shaped, the limbs are modified into flippers for swimming, and these turtles are not able to support their weight on land. The Hard-shelled sea turtles are omnivorous and feed on a variety of marine animals including: sponges, cnidarians, mollusks, crustaceans, and fish. Adult turtles have relatively few natural predators, although tiger sharks and saltwater crocodiles are known to consume adults. Eggs and hatchlings are the most vulnerable, and fall prey to many carnivorous species. Courtship and mating usually occur in shallow waters with the pair floating near the surface, with the male’s carapace protruding from the water. Females reproduce on multi-year cycles, but produce multiple clutches within a single season. Nesting occurs at night (except in Lepidochelys), and a range of seven to 238 eggs (averages vary across species) are deposited in a single clutch. Most, if not all, members of the family are in need of conservation. Development has reduced nesting areas, turtles are harvested for food and shells, and humans collect eggs for food. Additionally, turtles are part of the by-catch of commercial shrimp boats, and damaged by pollution.

Loggerhead, Caretta caretta 

Green Turtle, Chelonia mydas 

Hawksbill, Eretmochelys imbricata 
Olive Ridley, Lepidochelys olivacea 

Leatherbacks — Family Dermochelyidae

The family Dermochelyidae contains a single living species, Dermochelys coriacea. But the family has been around since the Cretaceous. Fossils of D. coriacea are unknown, but Dermochelys pseudostracion is known from the Miocene of France and three extinct dermochelyid genera (Cosmochelys, Eosphargis, and Psephophorus) are known from the Eocene of Africa, Europe, and North America. Today, the Leatherback inhabits oceans worldwide. The Leatherback is the largest extant turtles, reaching sizes of 2.44 m in carapace length and over 800 kg. The carapace is a composite of osteoderms embedded in cartilage and oil producing its leathery texture. The head cannot be fully retracted within the shell, and the fourth cervical vertebra is biconvex. Seven keels or ridges are present on the carapace. It has physiological adaptations that prevent the loss of body heat (see below), allowing it to establish a range into colder waters than other sea turtles (Cheloniidae). It is relatively certain that the Cheloniidae form a monophyletic group with the Dermochelyidae, referred to as the Chelonioidea. The characters shared by the two families include elongation of digits 3 and 4, flattening of the carpals and tarsals, and articulation between the neural spine of the eighth cervical vertebra and the ventral surface of the nuchal bone. Other than aspects of nesting, little is known about the general or reproductive behavior of the Dermochelyidae. Females reproduce on a multi-year cycle, but may oviposit as many as six times within a single season. Between 50 and 170 eggs comprise a typical clutch. The Leatherback is pelagic and feeds almost exclusively on jellyfish, making this species susceptible to accidentally feeding on plastics floating in the oceans. Sharks, killer whales, and jaguars have been reported to injure adult turtles. Eggs and hatchlings are predated by members of every class of vertebrates and numerous invertebrates.

Leatherback, Dermochelys coriacea 

Freshwater Turtles — Family Emydidae

Emydids or pond turtles are restricted to the Western Hemisphere with the exception of the genus Emys (European ponds turtles). About 50 species in10 genera compose the family. The limbs of most these turtles are adapted for swimming and most have some of webbing between the digits. Guillon et al. (2012) used mtDNA and nDNA to study turtle phylogeny and found the Emydidae was the sister to Platysteronon megacephalum (the Asian big-headed turtle), and together they formed the sister to the Tesudinidae and Bataguridae. A single invasive species occurs in Trinidad and possibly Tobago, Trachemys scripta elegans, the red-eared slider from North America, a species popular in the pet trade, and a species that is quickly becoming cosmopolitan with human help.

Red-eared Slider, Trachemys scripta elegans 

Asian River Turtles, Family Geoemyidae

Geoemydids live in freshwater and coastal marine ecosystems, as well as tropical and subtropical forests of Asia, Europe and North Africa. In the Western Hemisphere there is only one genus Rhinoclemmys, which is found in Central and South America. Geoemydidae is the most specious and diverse family in the order Chelonia with about 75 species in about 25 genera. They range in size from 10–80 cm, and most species show sexual dimorphism- males are usually smaller than females. Webbed toes and a pelvic girdle that articulates with the plastron making it flexible are found in all species. The carapace has 24 marginal scutes and the plastron is composed of 12 scutes and has no mesoplastron, the pectoral and abdominal scutes contact the marginal scutes. Most are herbivorous, but some are omnivorous and carnivorous. Females lay small clutches of eggs, several times a year. Some species have temperature-dependent sex determination while others have sex chromosomes. Fossils and molecular data support their close relationship to the tortoises, family Testudinidae. One species is found on Trinidad, Rhinoclemmys punctularia.

Galup, Rhinoclemmys punctularia 

Mud Turtles, Family Kinosternidae

The family Kinosternidae has 25 species in five genera. The genera of the subfamily Staurotypinae (Claudius and Staurotypus) range from Mexico southward into northern Central America. The Kinosterninae subfamily genera, Kinosternon and Sternotherus, range from southern Canada southward through much of South America. Kinosternids are small turtles (10−20 cm) with a highly domed carapace that has a distinct mid-dorsal keel. Females tend to be larger than males. There is one species of Kinosternon known from Trinidad, but subfossil remains of Claudius have been reported from Indian middens. Iverson et al. (2013) used tissues from every recognized species and most subspecies, and sequenced three mitochondrial (cyt b, 12S, 16S) and three nuclear markers (C-mos, RAG1, RAG2). They found three well-resolved clades within the Kinosterninae (aged >22 MYA), only two of which have been named: Sternotherus and Kinosternon. They describe the third clade, Cryptochelys, as a new genus. The evolutionary relationships among most species were well resolved, although those belonging to the K. scorpioides species group will require more extensive geographic and genetic sampling. They found support for three separate dispersals into South America, at least two of which preceded the closure of the Panamanian portal.

Scorpion Mud Turtle, Kinosternon scorpioides 

Tortoises, Family Testudinidae

The earliest Testudinidae fossils are reported from the lower Paleocene of Asia however older fossils of a possible ancestor (family Lindholmemydidae) are known from the upper Cretaceous of Asia. Evidence to date supports a late Mesozoic or early Cenozoic origin for the Testudinidae in Asia, with subsequent dispersal to North America, Europe, and Africa achieved by the Eocene. Testudinidae contains about 11 genera and 50 species. Tortoises occur on all continents except Antarctica and Australia, and all are terrestrial and inhabit tropical and warm temperate climates in habitats ranging from rain forests to deserts. Tortoises range in size from 12 to 130 cm. The carapace is usually domed, and the plastron usually lacks a hinge. Tortoises have forelegs with heavy scales on the anterior surface, and elephantine rear legs with short, web-less feet, and short digits. Usually they are herbivores, feeding on grasses, sedges, flowers, succulents, and fruits, but some feed on carrion. Females produce clutches that usually have less than 10 eggs, but may produce multiple clutches per season. Testudinidae shared an ancestor with the Geoemyidae about 52 MYA. There are two species of tortoises in Trinidad and Tobago (Chelonoidis carbonaria, C. denticulata ) it is unclear if both are native, or if one of the species (C. carbonaria) has been introduced by humans. A phylogeographic study that involved both Trinidad tortoise species suggests a divergence time between C. carbonaria and C. denticulata of 13.32 MYA. The study found evidence for a subdivision of Chelonoidis carbonaria in genetically distinct, geographically vicariant populations, while C. denticulata seemed to represent a more or less homogenous species. This suggests a correlation between habitat preference and phylogeographic differentiation. They hypothesize that the contiguous Amazonian rainforest allows gene flow between populations of the forest-dwelling C. denticulata throughout the species’ range. In contrast to C. carbonaria prefers savannas and open habitats, resulting in the genetic structure corresponding to its patchy distribution associated with savanna habitats.

Red-footed Tortoise, Chelonoidis carbonaria 

Yellow-footed Tortoise, Chelonoidis denticulata 

Family Chelidae
Chelus fimbriata (Schneider)
Testudo Fimbriata Schneider, 1782:349. Type locality: Uprouague and Remire Island, French Guiana.
Chelus fimbriatus: Mertens and Muller, in Rust, 1934:65.
Chelys fimbriatus: Underwood, 1962: 173.
Chelys fimbriata: MacLean et al. 1977:45.
Mesoclemmys gibba (Schweigger)
Emys gibba Schweigger, 1812:299. Type locality: unknown.
Phrynops gibbus  Diesing, 1850:406.
Hydrapsis Gordoni Gray, 1868:563, pl. 42.
Hydrapsis gibba  Mole and Urich, 1894a:79.
Mesoclemmys gibba  Underwood, 1962: 172.
Phrynops (Mesoclemmys) gibbus: Pritchard and Trebbau, 1984:119.
Family Cheloniidae
Caretta caretta (Linnaeus)
Testudo caretta Linnaeus, 1758: 197. Type locality: "insulus Americanas," restricted to Bermuda by Smith and Taylor (1950); and to Bimini, British Bahamas by Schmidt (1953).
Testudo marina ― Court, 1858:440.
Thalassochelys Caretta ― Mole and Urich, 1894a:78.
Caretta caretta ― Stejneger, 1904:715.
Chelonia mydas (Linnaeus)
Testudo mydas Linnaeus. 1758:197. Type locality: "Insulus pelagi: insulam Adscension."' Mertens and Muller (1928) restricted it to Ascension Island, in the South Atlantic.
Chelonia Mydas ― Schweigger,1812:291.
Chelone mydas ― Mole and Urich, 1894a:78.
Eretmochelys imbricata imbricata (Linnaeus)
Testudo imbricata Linnaeus 1766:350. Type locality: "Mari Americano, Asiatico," restricted by Smith and Taylor (1950:16) to the Bermuda Islands; and by Schmidt (1953: 106) to Belize, British Honduras.
Chelone imbricata ― Mole and Urich, 1894a:78.
Eretmochelys imbricata imbricata ― Mertens and Muller, 1928:23.
Lepidochelys olivacea (Eschscholtz)
Chelonia olivacea Eschscholtz, 1829:3. Type locality: "China sea, Monila Bay, and Sumatra."
Lepidochelys olivacea: Fitzinger, 1843:30
Family Dermochelyidae
Dermochelys coriacea (Linnaeus)
Testudo coriacea Linnaeus. 1766:350. Type locality: "Mari mediterraneo, Adriatico various," Smith and Taylor (1950:13) restricted it to Palermo, Sicily. Based upon data with the type specimen Fretey and Bour (1980) corrected the type locality to: "Tyrrhenian coast near Rome, Italy." [See the note on this in Pritchard and Trebbau, 1984: 266-267.]
Testudo Marina: Court, 1858:440.
Dermochelys coriacea: B1ainville, 1816:119.
Family Geoemyidae
Rhinoclemmys punctularia punctularia (Daudin)
Testudo punctularia Daudin, 1801:249. Type locality: "Cayenne."
?Emys― Court, 1858:440.
Nicoria punctularia― Boulenger, 1889a:124.
Geomyda punctularia―Beebe, 1952: 175.
Geomyda punctariola― Underwood, 1962: 172.
Rhinoclemmys punctularia punctularia― Ernst, 1981:1.
Family Kinosternidae
Kinosternon scorpioides scorpioides (Linnaeus)
Testudo scorpioides Linnaeus, 1766:352. Type locality: Suriname.
Kinosternon scorpioides: Gray, 1831a:34.
Cinosternum scorpioides: Roux, 1926:292.
Kinosternon scorpioides scorpioides: Mertens and Wermuth, 1955:337
Family Pelomedusidae
Podocnemis expansas (Schweigger)
Emys expansa Schweigger, 1812. Type locality: South America.
Podocnemis expansa ― Wagler, 1830: plate 4.
Podocnemis unifilis Troschel
Podocnemis unifilis Troschel, 1848 in Schomburgk, 1848:647. Type locality: Rupununi and Takutu Rivers, British Guiana.
Family Testudinidae
Chelonoidis carbonaria (Spix)
Testudo carbonaria Spix. 1824a:22. Type locality: "Capitary.'·
Geochelone carbollaria ― Williams, 1960:10.
Chelonoides carbonaria― Fritz and Binida-Emonds, 2007.
Chelonoidis denticulata (Linnaeus)
Testuddenticulara Linnaeus, 1766:325. Type locality: "Virginia," in error.
Testudo tabulata: Court, 1858:400.
Geochelone denticulata: Williams, 1960: 10.
Chelonoides denticulata: Fritz and Binida-Emonds, 2007.