Published January 27, 2023. Open access.

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Big-headed Amazon River Turtle (Peltocephalus dumerilianus)

Reptiles of Ecuador | Testudines | Podocnemididae | Peltocephalus dumerilianus

English common name: Big-headed Amazon River Turtle.

Spanish common names: Charapa cabezona, tortuga cabezona de la Amazonía, guacamaya, cabezona, tortuga de cuello escondido.

Recognition: ♂♂ 52 cmMaximum straight length of the carapace. ♀♀ 47 cmMaximum straight length of the carapace..1 The big-headed Amazon River Turtle (Peltocephalus dumerilianus) can be distinguished from other river turtles by having a large “armored” head covered with shield-like plates and eyes located laterally on the skull.13 The plastron is elongated but does not cover the entire length of the carapace, which is grayish brown and has an oval and domed shape (Fig. 1).1 The extremities are slightly webbed, with five claws on the forelimbs and four on the hindlimbs.1,2 In juveniles, the carapace scutes have growth rings, but these fade in adults.2 Males are larger and have longer tails than females.4 This species can be differentiated from turtles of the genus Podocnemis by having a smooth forehead without a groove between the eyes.1

Figure showing variation among individuals of Peltocephalus dumerilianus

Figure 1: Individuals of Peltocephalus dumerilianus from the eastern Amazon basin.

Natural history: Peltocephalus dumerilianus is an extremely rareTotal average number of reported observations per locality less than three. species in Ecuador: only three records are known.5,6 Big-headed River Turtles are crepuscular, nocturnal, and inhabit the bottom of black-water rivers and lagoons in well-preserved seasonally flooded lowland rainforests.1,3 They can also be found in smaller numbers in rivers of white and clear waters.4 They are secretive and prefer to shelter in cavities or under submerged tree trunks. Due to their scant finger webbing, these turtles have poor swimming abilities and prefer to walk on the banks of rivers, away from the current.1 Their average home range size is ~9 km2 (about half the size of a soccer field) and females tend to cover greater distances (7.42 km) than males (5.72 km).7,8 The rate of movement increases during both low-water season and when water temperatures are lower.8 Big-headed River Turtles have an omnivorous diet that includes a high proportion of both aquatic and terrestrial plant material (particularly leaves that fall into the water), algae, aquatic plants, seeds, but also insects, fish, mollusks, crustaceans, and even conspecifics (an adult female ingested eggs9).1,3 The distinctive “armored” head of P. dumerilianus is probably associated with defense.3 Bites to humans have resulted in mutilated fingers and the sharp claws of the turtle are also capable of causing serious injuries.3 Natural predators of eggs of P. dumerilianus include lizards and iguanas (Iguana iguana), whereas crocodilians (Melanosuchus niger), jaguars, raptors, and primates eat juveniles and adults.1,3

Sexual maturity in both males and females of Peltocephalus dumerilianus begins when they reach 25–30 cm in straight carapace length.2,3 Egg-laying takes place once a year and is related to the local hydrological cycle.3 Females are unique among Podocnemididae turtles in that they usually do not nest on sandy beaches,3 but in solitary and concealed nests in a wide range of locations, including streams banks, under foliage in clearings, beneath shrubs and grasses, in termite mounds, in sandy ravines near water, between roots, and even in recently-burned areas.3 The clutch size is 3–25 (usually 7–15) eggs and the incubation time is 74–135 days, around 3–5 months.1,3 The eggs are 50–63 mm in length, 33–43 mm wide, and weigh 36–54 g.1 Eggs exhibit temperature-dependent sex determination: average temperatures of 29.73–30.83 °C produce a higher number of males, while low temperatures favor a higher proportion of females.1 It is estimated that in nature 50–95% of eggs hatch.1 In the wild, one individual was recaptured after 19 years.8

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Conservation: Vulnerable Considered to be facing a high risk of extinction in the mid-term future..10 Although Peltocephalus dumerilianus is a widely distributed species that occurs in protected areas, it is listed in this category mainly due to overexploitation.2 Big-headed River Turtles are hunted for consumption, medicinal use, or to be used or sold as pets.3 The blood is used to kill ants or as an anti-inflammatory medication, treatment for snake bites, and even against strokes.3

Distribution: Peltocephalus dumerilianus is native to an estimated area of 2,058,635 km2 throughout much of the northern Amazon basin.5 In Ecuador, the species is known from three localities at elevations between 122 and 329 m (Fig. 2).

Distribution of Peltocephalus dumerilianus in Ecuador

Figure 2: Distribution of Peltocephalus dumerilianus in Ecuador. See Appendix 1 for a complete list of the presence localities included in the map.

Etymology: The name Peltocephalus, which comes from the Latin words pelta (meaning “shield”) and cephalus (meaning “head”),11 refers to the large head shields. The specific epithet dumerilianus honors André Marie Constant Duméril (1774–1860), a French herpetologist best known for publishing the encyclopedia Erpétologie Général.

See it in the wild: Big-headed Amazon River Turtles cannot be expected to be seen reliably in the wild in Ecuador. Only three records are known in the country. Furthermore, the aquatic and bottom-dwelling habits of this species make it extremely hard to detect in natural settings.

Acknowledgments: Special thanks to Quetzal Dwyer of Reptilandia for providing access to the specimens of Peltocephalus dumerilianus photographed in this account.

Authors: Gabriela SandovalaAffiliation: Pontificia Universidad Católica del Ecuador, Quito, Ecuador. and Alejandro ArteagabAffiliation: Khamai Foundation, Quito, Ecuador.

Photographer: Jose VieiracAffiliation: Tropical Herping (TH), Quito, Ecuador.,dAffiliation: ExSitu, Quito, Ecuador.

How to cite? Sandoval G, Arteaga A (2023) Big-headed Amazon River Turtle (Peltocephalus dumerilianus). In: Arteaga A, Bustamante L, Vieira J (Eds) Reptiles of Ecuador: Life in the middle of the world. Available from: DOI: 10.47051/ZHDO7334

Literature cited:

  1. De La Ossa J, Vogt RC, De La Ossa-Lacayo A, Lasso CA (2012) Peltocephalus dumerilianus. In: Páez VP, Morales-Betancourt MA, Lasso CA, Castaño-Mora OV, Bock BC (Eds) Biología y conservación de las tortugas continentales de Colombia. Serie Editorial Recursos Hidrobiológicos y Pesqueros Continentales de Colombia, Instituto de Investigación de Recursos Biológicos Alexander von Humboldt (IAvH), Bogotá, 340–348.
  2. Rueda-Almonacid JV, Carr JL, Mittermeier RA, Rodríguez-Mahecha JV, Mast RB, Vogt RC, Rhodin AGJ, de la Ossa-Velásquez J, Rueda JN, Mittermeier CG (2007) Las tortugas y los cocodrilianos de los países andinos del trópico. Conservación Internacional, Bogotá, 538 pp.
  3. Gentil E, Azevedo de Medeiros L, Vogt R, Barnett AA (2021) Biology of the Big-headed Amazon River Turtle, Peltocephalus dumerilianus (Schweigger, 1812) (Testudines, Pleurodira): the basal extant Podocnemididae species. Herpetozoa 34: 207–222. DOI: 10.3897/herpetozoa.34.e67807
  4. Pritchard PCH, Trebbau P (1984) Turtles of Venezuela. Society for the Study of Amphibians and Reptiles, 403 pp.
  5. Rhodin AGJ, Iverson JB, Bour R, Fritz U, Georges A, Shaffer HB, van Dijk PP (2021) Turtles of the world: annotated checklist and atlas of taxonomy, synonymy, distribution, and conservation status. Chelonian Research Monographs 8: 1–472. DOI: 10.3854/crm.8.checklist.atlas.v9.2021
  6. Orcés GV (1949) Los testudinata ecuatorianos que se conservan en las colecciones de Quito, Ecuador. Boletín de Informaciones Científicas Nacionales 3: 13–22.
  7. De La Ossa J, Vogt RC (2011) Ecologia populacional de Peltocephalus dumerilianus (Testudines, Podocnemididae) em dois tributários do Rio Negro, Amazonas, Brasil. Interciência 36: 53–58.
  8. Duarte de Castro NG (2013) Movimentação e área de uso de adultos de Peltocephalus dumerilianus (Testudines, Podocnemididae) na Reserva Biológica do Rio Trombetas, Pará. MSc thesis, Manaus, Instituto Nacional de Pesquisas da Amazônia - INPA, 30 pp.
  9. De la Ossa J, Vogt R, De la Ossa-Lacayo A (2009) Discovery of cannibalistic oophagy in Peltocephalus dumerilianus (Testudines: Podocnemididae). Actualidades Biológicas 31: 79–82.
  10. Tortoise & Freshwater Turtle Specialist Group (1996) Peltocephalus dumerilianus. The IUCN Red List of threatened species. Available from: DOI: 10.2305/IUCN.UK.1996.RLTS.T16511A5972664.en
  11. Brown RW (1956) Composition of scientific words. Smithsonian Books, Washington D.C., 882 pp.

Appendix 1: Locality data used to create the distribution map of Peltocephalus dumerilianus in Ecuador (Fig. 2). Go to the section on symbols and abbreviations for a list of acronyms used.

BrazilAmazonasRío San AntonioiNaturalist
ColombiaAmazonasPuerto NariñoFerrara et al. 2017
ColombiaAmazonasRío TrompeteroFerrara et al. 2017
ColombiaCaquetáAracuaraFerrara et al. 2017
ColombiaCaquetáQuebrada La CulebraFerrara et al. 2017
ColombiaCaquetáRío YariRhodin et al. 2021
ColombiaPutumayoEl EncantoRhodin et al. 2021
ColombiaPutumayoLaguna ApayaMedem 1960
ColombiaPutumayoRío Putumayo, near Puerto AsísDe la Ossa, 2013
ColombiaVichadaReserva natural BojonawiPhoto by Carlos Lasso
EcuadorOrellanaTiputini Biodiversity StationRhodin et al. 2021
EcuadorPastazaBoca del Río BobonazaOrcés 1949
EcuadorPastazaEl PorvenirOrcés 1949
PeruLoretoGüeppiRhodin et al. 2021
PeruLoretoIquitosRhodin et al. 2021