Pelusios
Pelusios castaneus.jpg
Pelusios castaneus
Scientific classification e
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
Anota Gray, 1863
Notoa Gray, 1863
Tanoa Gray, 1863

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).

Etymology

The Latin name Pelusios means "mud" or "clay",[citation needed] and this is reflected by the turtles habitually burying themselves to find refuge and food.[citation needed]

Common names

Common names for the genus Pelusios include hinged terrapins,[3] African mud turtles, and mud terrapins.

Taxonomy

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.

Geographic range

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.

Description

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.[4] The carapaces are oblong, moderately high-domed, and the plastrons are large and hinged which is what distinguishes them from the Pelomedusa.[4][5] The plastron contains a mesoplastron and also well-developed plastral buttresses that articulate with the costals on each side of the carapace.[4] The carapace has 11 pairs of sutured peripherals around its margin and a neck without costiform processes.[4] 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.[4] The head shape is wide and flat, with a seemingly "smiling" face created by the jaw closure.[5] 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.[4]

Biology

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.[4] 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.[4] 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.[5] Pelusios generally produce small to modest clutches of 6 to 18 eggs, depending upon female size.[4][6] Egg deposition occurs in the more equitable season of the year, with known incubation periods ranging from 8–10 weeks.[4] The reported karyotype is 2N = 34 with 22 macrochromosomes and 12 microchromosomes.[7] The southern group of the genus Pelomedusa is shown to be paraphyletically similar to Pelusios through mitochondrial DNA analyses.[2][8] From fossil evidence, it is suggested that the genera diverged in, or before the lower Miocene era.[8]

List of species

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][7] Species in the "subniger group" exhibit greater mobility of the plastral front lobe than those belonging to the "adansonii group".

Common name Scientific name[1][9][a] IUCN Red List status[10] Picture
Adanson's mud turtle Pelusios adansonii
(Schweigger, 1812)
LC
Okavango mud turtle Pelusios bechuanicus
V. FitzSimons, 1932
LC
Turkana mud turtle Pelusios broadleyi
Bour, 1986
VU
African keeled mud turtle Pelusios carinatus
Laurent, 1956
LC
West African mud turtle Pelusios castaneus
(Schweigger, 1812)
LC
Yellow-bellied mud turtle Pelusios castanoides
Hewitt, 1931

Subspecies:

  • P. c. castanoides Hewitt, 1931
  • P. c. intergularis Bour, 1983
LC
Central African mud turtle Pelusios chapini
Laurent, 1965[11]
LC
Ivory Coast mud turtle Pelusios cupulatta
Bour & Maran, 2003
NE
African forest turtle Pelusios gabonensis
(A.H.A. Duméril, 1856)
LC
Pelusios marani
Bour, 2000
NE
African dwarf mud turtle Pelusios nanus
Laurent, 1956
DD
West African black turtle Pelusios niger
(A.M.C. Duméril & Bibron, 1835)
LC
Variable mud turtle Pelusios rhodesianus
Hewitt, 1927
LC
Serrated hinged terrapin Pelusios sinuatus A. Smith, 1838 LC
East African black mud turtle Pelusios subniger
(Lacépède, 1789)

Subspecies:

  • P. s. subniger (Lacépède, 1789)
  • P. s. parietalis Bour, 1983
LC
Upemba mud turtle Pelusios upembae
Broadley, 1981
DD
Williams' mud turtle Pelusios williamsi
Laurent, 1965

Subspecies:

  • P. w. williamsi Laurent, 1965
  • P. w. laurenti Bour, 1984
  • P. w. lutescens Laurent, 1965
LC

Status

Based on field surveys, a 50% decrease has been observed in the Seychelles terrapins, which include various Pelusios species.[12] 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.[13] The species are endangered due to threat of drainage, predation, and invasion by alien flora, combined with a shrunken living area.[12][13] Most habitat destruction is from human population expansion, specifically in the granitic islands due to increased development pressures.[13] Hope for reversal of this trend is evidenced by the rapid population recovery of Pelusios subniger parietalis on Frégate Island after habitat improvement.[12] Global climate change has recently been recognized as one of the largest threats to biodiversity.[14] This climate change has the ability to change species survival by causing changes in ecosystem structures,[13] yet the effect is heightened in endemic species.[14] 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.[15] Climate change is likely to be devastating for many species confined to small islands such as Seychelles.[13] Endemic species such as Pelusios could suffer the worst impact of climate change because of their restricted range and narrow ecological requirements.

Notes

  1. ^ A binomial authority in parentheses indicates the species was originally described in a genus other than Pelusios.

References

  1. ^ a b c Rhodin et al. 2011, p. 000.215
  2. ^ a b c d e Fritz & Havaš 2007, pp. 345–346
  3. ^ Branch, Bill. 2004. Field Guide to Snakes and Other Reptiles of Southern Africa. Sanibel Island, Florida: Ralph Curtis Books. 399 pp. ISBN 0-88359-042-5. (Genus Pelusios, p. 46).
  4. ^ a b c d e f g h i j Vitt, Laurie; Calwell, Janalee (2008). Herpetology. Wiltham, Massachusetts: Academic. ISBN 978-0-12-374346-6.
  5. ^ a b c Bonin, Franck; Devaux, Bernard; Dupre, Alain (2006). Turtles of the World (Third ed.). Baltimore, Maryland: Johns Hopkins University Press. ISBN 0-8018-8496-9.
  6. ^ Franklin, C (2007). Turtles: An extraordinary natural history 245 million years in the making. St. Paul, Minnesota: Voyageur Press. ISBN 978-0-7603-2981-8.
  7. ^ a b Ernst, C; Barbour, R. (1989). Turtles of the World. Washington D.C.: Smithsonian Press. ISBN 0-87474-414-8.
  8. ^ a b Vargas-Ramirez M, Vences M, Branch WR, Daniels SR, Glaw F, Hofmeyr MD, Kuchling G, Maran J, Papenfuss TJ, Siroký P, Vieites DR, Fritz U. (July 2010). "Deep genealogical lineages in the widely distributed African helmeted terrapin: Evidence from mitochondrial and nuclear DNA". Molecular Phylogenetics and Evolution. 56: 428–440. doi:10.1016/j.ympev.2010.03.019. PMID 20332032.((cite journal)): CS1 maint: multiple names: authors list (link)
  9. ^ The Reptile Database. www.reptile-database.org.
  10. ^ Turtle Taxonomy Working Group [van Dijk, P.P., Iverson, J.B., Rhodin, A.G.J., Shaffer, H.B., and Bour, R.]. 2014. "Turtles of the World, 7th edition: annotated checklist of taxonomy, synonymy, distribution with maps, and conservation status". In: Rhodin, A.G.J., Pritchard, P.C.H., van Dijk, P.P., Saumure, R.A., Buhlmann, K.A., Iverson, J.B., and Mittermeier, R.A. (Eds.). Conservation Biology of Freshwater Turtles and Tortoises: A Compilation Project of the IUCN/SSC Tortoise and Freshwater Turtle Specialist Group. Chelonian Research Monographs 5(7):000.329–479 doi:10.3854/crm.5.000.checklist.v7.2014
  11. ^ Bruce G. Marcot, "Two Turtles from Western Democratic Republic of the Congo: Pelusios chapini and Kinixys erosa." Includes photos.
  12. ^ a b c Gerlach, J (August 2008). "Fragmentation and demography as causes of population decline in Seychelles freshwater turtles (genus Pelusios)". Chelonian Conservation and Biology. 7: 78–87. doi:10.2744/ccb-0635.1.
  13. ^ a b c d e Bombi, Pierluigi; D'Amen, Manuela; Gerlach, Justin; Luiselli, Luca (2009). "Will climate change affect terrapin conservation in Seychelles". Phelsuma (17A): 1–12.
  14. ^ a b Thomas CD, Cameron A, Green RE, Bakkenes M, Beaumont LJ, Collingham YC, Erasmus BFN, de Siqueira MF, Grainger A, Hannah L, Hughes L, Huntley B, van Jaarsveld AS, Midgley GF, Miles L, Ortega-Huerta MA, Peterson AT, Phillips OL, Williams SE. 2004. "Extinction risk from climate change". Nature 427: 145–148.
  15. ^ Hulme M. 1996. Climate Change and Southern Africa: an Exploration of Some Potential Impacts and implications in the SADC. Norwich: United Kingdom: WWF International and Climate Research Unit, UEA. 104 pp.

Bibliography