| Pelusios | |
|---|---|
 | |
| Pelusios castaneus | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | Testudines |
| Suborder: | Pleurodira |
| Family: | Pelomedusidae |
| Genus: | Pelusios Wagler, 1830 [1] [2] |
| Species | |
See text | |
| Synonyms [1] [2] | |
Sternothaerus Bell, 1825 Contents | |
Pelusios is a genus of African side-necked turtles. With 17 described species, it is one of the most diverse genera of the turtle order (Testudines).
The scientific name Pelusios is derived from the Greek word pēlos, which means "mud" or "clay", [3] and this is reflected by the turtles living in streams and rivers with a muddy bottom.
Common names for the genus Pelusios include hinged terrapins, [4] African mud turtles, and mud terrapins.
Several species have been described, with probably numerous undescribed species. The taxonomy of the genus is very confused, as these species show many local variations. Certain species, in isolated areas or with reduced populations, need to be observed as they face a distinct extinction possibility given the significant number collected by native people.
They are found throughout Sub-Saharan Africa, Madagascar, São Tomé, and the Seychelles islands. They have also been introduced on the islands of the Lesser Antilles.
The African mud turtles range from being small in size, only 12 cm (4.7 in) carapace length for adult Pelusios nanus , to moderately large, 46 cm (18 in) for adult Pelusios sinuatus , while the large majority of species fall between 20 and 30 cm (7.9 and 11.8 in) carapace length. [5] The carapaces are oblong, moderately high-domed, and the plastrons are large and hinged which is what distinguishes them from the Pelomedusa . [5] [6] The plastron contains a mesoplastron and also well-developed plastral buttresses that articulate with the costals on each side of the carapace. [5] The carapace has 11 pairs of sutured peripherals around its margin and a neck without costiform processes. [5] The jaw closure articulates on a pterygoid trochlear surface which lacks a synovial capsule but instead contains a saclike duct full of fluid from the mouth cavity. [5] The head shape is wide and flat, with a seemingly "smiling" face created by the jaw closure. [6] The skull lacks the epipterygoid bone (bone above the pterygoid extending to parietal bone) and parietal-squamosal contact but possesses an internal carotid canal and strong postorbital-squamosal contact. [5]
The mud terrapins are either semiaquatic or fully aquatic and typically walk on the floor of slow-moving waters. They are most often observed in lakes, swamps or marshes but occasionally witnessed in ephemeral waterways. [5] They are predominantly carnivorous, eating a variety of arthropods, worms, or other small animals found by way of foraging the bottom of their aquatic habitats. [5] They do not undergo prolonged estivation or hibernation in the dried mud during dry season; instead, they need to find a wet or humid place to survive. [6] Pelusios generally produce small to modest clutches of 6 to 18 eggs, depending upon female size. [5] [7] Egg deposition occurs in the more equitable season of the year, with known incubation periods ranging from 8–10 weeks. [5] The reported karyotype is 2N = 34 with 22 macrochromosomes and 12 microchromosomes. [8] The southern group of the genus Pelomedusa is shown to be paraphyletically similar to Pelusios through mitochondrial DNA analyses. [2] [9] From fossil evidence, it is suggested that the genera diverged in, or before the lower Miocene era. [9]
The species in the genus Pelusios can be divided into two groups based on shell morphology. The "adansonii group" (also known as the "gabonensis group" or the "adansonii-gabonensis group") includes P. adansonii, P. broadleyi, P. gabonensis, P. marani, and P. nanus. Species in the "adansonii group" are characterized by short abdominal scutes relative to the elongate anterior plastral lobe, as well as a short bridge between the carapace and the plastron. [2] All of the remaining species are characterized by relatively longer abdominal scutes and a longer bridge between the carapace and plastron and are referred to as the "subniger group". [2] [8] Species in the "subniger group" exhibit greater mobility of the plastral front lobe than those belonging to the "adansonii group".
Based on field surveys, a 50% decrease has been observed in the Seychelles terrapins, which include various Pelusios species. [13] Seychelles is considered a hotspot for biodiversity, as it is one of the most threatened reservoirs of plant life and animal life, as well as one of the richest environments. [14] The species are endangered due to threat of drainage, predation, and invasion by alien flora, combined with a shrunken living area. [13] [14] Most habitat destruction is from human population expansion, specifically in the granitic islands due to increased development pressures. [14] Hope for reversal of this trend is evidenced by the rapid population recovery of Pelusios subniger parietalis on Frégate Island after habitat improvement. [13] Global climate change has recently been recognized as one of the largest threats to biodiversity. [15] This climate change has the ability to change species survival by causing changes in ecosystem structures, [14] yet the effect is heightened in endemic species. [15] Several reviews undertaken for the study of potential effects of global warming on biodiversity have provided evidence for Africa being the most vulnerable of all continents. [16] Climate change is likely to be devastating for many species confined to small islands such as Seychelles. [14] Endemic species such as Pelusios could suffer the worst impact of climate change because of their restricted range and narrow ecological requirements.
Pelomedusidae is a family of freshwater turtles endemic to sub-Saharan Africa, including Madagascar, São Tomé, and the Seychelles. They range in size from 12 to 45 cm in carapace length, and are generally roundish in shape. They are unable to fully withdraw their heads into their shells, instead drawing them to the side and folding them beneath the upper edge of their shells, hence are called African side-necked turtles.
Macrochelys is a genus of very large freshwater turtles in the family Chelydridae, native to the Southeastern and Midwestern United States. Only a single extant species was recognized until 2014, when a study divided it into two, or possibly three species. These turtles are easily recognized by three distinct dorsal ridges with raised spikes.
The big-headed pantanal swamp turtle or pantanal swamp turtle is a species of turtle in the family Chelidae found in Brazil, Bolivia, Argentina, and Paraguay.
The New Guinea snake-necked turtle is a species of turtle in the family Chelidae. The species is found almost exclusively within Western Province, Papua New Guinea.
Pelusios broadleyi, commonly known as the Turkana mud turtle, Broadley's mud turtle, or the Lake Turkana hinged terrapin, is a species of turtle in the family Pelomedusidae. The species is native to eastern Africa.
The variable mud turtle, also known as Rhodesian mud turtle, Mashona hinged terrapin or variable hinged terrapin, is a species of turtle in the family Pelomedusidae. It is widely distributed in Central, East, and Southern Africa. The species was officially described by John Hewitt in 1927 and had to be broken into subspecies due to color variations on the heads of the turtles acrost the regions.
The East African black mud turtle, also known as the Pan terrapin, is a species of turtle in the family Pelomedusidae, native to eastern and southeastern Africa.
Dahl's toad-headed turtle is a medium-sized species of side-necked turtle in the family Chelidae. This critically endangered freshwater turtle is endemic to northern Colombia, where it lives in small pools, streams, and swamps, but aestivates on land.
Cyclemys is a genus of freshwater turtles, commonly referred to as Asian leaf turtles, from the family Geoemydidae. The genus occurs throughout Southeast and South Asia, and currently contains seven species.
Elseya albagula, commonly known as the white-throated snapping turtle, is one of the largest species of chelid turtles in the world, growing to about 45 cm (18 in) carapace length.
Chelodina canni, also known commonly as Cann's snake-necked turtle, is a species of turtle in the family Chelidae. The species is endemic to Australia, where it is found in the northern and northeastern parts of the continent. It has a narrow zone of hybridization with its related species the eastern snake-necked turtle, C. longicollis. For many years C. canni was assumed to be the same species as C. novaeguineae from New Guinea. However, in 2002 it was shown that these two species differ both morphologically and genetically, and therefore C. canni was separated and described as a unique species.
Chelodina (Chelydera) burrungandjii, the sandstone snake-necked turtle or Arnhem Land long-necked turtle, is a medium-sized turtle reaching carapace lengths of 316 mm. The species is found in the sandstone plateaus and escarpments and the plunge pools of Arnhem Land of the Northern Territory. The species had been long recognised as valid. However, it had been difficult to research due to the remoteness of its habitat. Efforts to breed this species in captivity had been largely unsuccessful, until National Aquarium Herpetologist Matthew Benedict lead a successful breeding project in 2021. The species occurs in proximity to Chelodina rugosa, to which it is closely related. For the most part the two species are parapatric in distribution. However, they do come together in limited locations such as plunge pools at the base of the escarpments. In these areas there is hybridization between the species.
The Assam leaf turtle is a species of turtle in the family Geoemydidae. The species is native to India, Nepal, Bhutan, and Bangladesh.
Cyclemys enigmatica, also known as the enigmatic leaf turtle, is a species of Asian leaf turtle. It is found in the Greater Sunda Islands and the Malay Peninsula.
The western black-bridged leaf turtle is a species of Asian leaf turtle found in southern Indochina.
The eastern black-bridged leaf turtle is a species of Asian leaf turtles found in southern Indochina.
The West African mud turtle, also known as the West African side-necked turtle or swamp terrapin, is a species of turtle in the family Pelomedusidae. Pelusios castaneus is a freshwater species and is endemic to West and Central Africa.
Adanson's mud turtle is a species of turtle in the family Pelomedusidae. The species is endemic to north-central Africa.
The Okavango mud turtle or Okavango terrapin) is a species of turtle in the family Pelomedusidae endemic to Africa. It is found in Angola, Botswana, the Democratic Republic of the Congo, Namibia (Caprivi), Zambia, and Zimbabwe.
The African forest turtle is a species of turtle in the family Pelomedusidae. It is endemic to Africa, where it can be found in Angola, Burundi, Cameroon, Equatorial Guinea, Gabon, the Democratic Republic of the Congo, the Republic of the Congo, Ghana, Tanzania, and Uganda
