Trionyx triunguis, 129

Trionyx triunguis (Forskål 1775) –
African Softshell Turtle, Nile Softshell Turtle

Pearson McGovern^1,2,3, Ertan Taskavak⁴, Peter A. Meylan⁵,
Luca Luiselli^1,6,7, Gift Simon Demaya⁸, Gabriel H. Segniagbeto⁹,
Mathias Behangana¹⁰, Fabio Petrozzi¹¹, Edem A. Eniang¹²,
Yaron Tikochinski¹³, and Mehmet K. Atatür^14†

¹Institute for Development, Ecology, Conservation & Cooperation,
via G. Tomasi di Lampedusa 33, I-00144 Rome, Italy [[email protected], [email protected]];
²Reserva: The Youth Land Trust, Washington, DC, USA [[email protected]];
³Turtle Survival Alliance, North Charleston, South Carolina, USA;
⁴Faculty of Fisheries, Ege University, Izmir, Türkiye [[email protected]];
⁵Natural Science, Eckerd College, 4200 54th Ave. South,
St. Petersburg, Florida 33711 USA [[email protected]];
⁶Department of Zoology, University of Lomé, Togo;
⁷Department of Environmental and Applied Biology,
Rivers State University of Science and Technology, P.M.B. 5080, Port Harcourt, Nigeria;
⁸Department of Wildlife, CNRES, University of Juba,
PO Box 82, Juba, Republic of South Sudan [[email protected]];
⁹Laboratory of Ecology and Ecotoxicology, Faculty of Sciences, University of Lomé,
Lomé 01 BP 1515, Togo [[email protected]];
¹⁰Makerere University Institute of Environment and Natural Resource,
P.O. Box 7298, Kampala, Uganda [[email protected]];
¹¹ORVICA Int., via Jenner 70, 00151 Roma, Italy [[email protected]];
¹²Department of Forestry and Wildlife, University of Uyo,
Uyo, Akwa-Ibom State, Nigeria [[email protected]];
¹³Department of Marine Sciences, Ruppin Academic Center,
Michmoret, Israel [[email protected]];
¹⁴Biology Department, Faculty of Science, Ege University, Izmir, Türkiye [deceased]

Summary. – The African Softshell Turtle, Trionyx triunguis (family Trionychidae), is a large (up to >100 cm straight-line carapace length), fresh- and salt-water tolerant species predominantly found in moderately deep streams, rivers, estuarine systems, and lakes. It is the most widely distributed turtle in Africa, ranging from the mouth of the Nile River system south to Lakes Turkana (Rudolf) and Albert in eastern Africa, and from the Cunene River in northern Namibia to Senegal in western Africa. Additionally, it is found in the western Mediterranean region from the Turkish coastal zone to Israel. African populations are thought to have experienced significant declines in recent decades and Mediterranean populations have been considered Critically Endangered by the IUCN. While there is little published about the habitat preferences and ecology of the species, it appears to prefer medium to large sized rivers and permanent waterbodies with muddy, organic substrates, abundant emergent vegetation, and forested banks. Most accounts of nesting come from Mediterranean populations, where nesting takes place between May and July–August, with hatchling emergence from July to September after an incubation of 54–75 days. Clutch sizes seem to be highly variable between studies, seasons, and countries, with clutch size averages ranging from 23.0–44.7 eggs; up to 66 eggs have been recorded. The near spherical eggs are roughly 30–35 mm in diameter and weigh ~20 g. Most nests are between 20–40 cm deep and laid within 15 m of the water’s edge. As seen in all other trionychids, T. triunguis does not exhibit temperature-dependent sex determination. Optimal nest temperatures are between 24–33ºC, with around 30ºC producing maximum hatching success. Nest predation seems to be high where nesting has been recorded, with monitor lizards, domestic dogs, weasels, foxes, and jackals reported as the predominant predators. Hatchlings typically measure 40–51 mm SCL and weigh 10–15 g. Double and triple clutching have been noted in the species (though the frequency of multiple clutches remains unknown). Other than high nest predation rates, threats include entanglement in fishing gear, subsistence hunting, targeted hunting for the bushmeat trade, wanton killing, pollution, sand mining, and destruction of nesting beaches and sandbanks. The species is estimated to be Vulnerable and decreasing throughout its range and increased conservation efforts are warranted.

Distribution. – Angola, Benin, Burkina Faso, Cameroon, Central African Republic, Chad, Congo (DRC), Congo (ROC), Egypt (extirpated), Equatorial Guinea, Eritrea, Ethiopia, Gabon, Gambia, Ghana, Greece (vagrant), Guinea, Guinea-Bissau, Israel, Ivory Coast (Côte d’Ivoire), Kenya, Lebanon, Liberia, Mali, Mauritania (extirpated?), Namibia, Niger, Nigeria, Senegal, Sierra Leone, Somalia, South Sudan, Sudan, Syria, Togo, Türkiye (Turkey), Uganda.

Synonymy. – Testudo triunguis Forskål 1775, Amyda triunguis, Trionyx triunguis, Pelodiscus triunguis, Aspidonectes triunguis, Tyrse triunguis, Amyda triunguis triunguis, Testudo striata Suckow 1798, Trionyx egyptiacus Geoffroy Saint-Hilaire 1809a, Trionyx aegyptiacus Geoffroy Saint-Hilaire 1809b, Trionyx (Aspidonectes) aegyptiacus, Testudo nilotica Shaw and Nodder 1810, Trionyx niloticus, Tyrse nilotica, Aspidonectes niloticus, Trionyx labiatus Bell 1835, Trionyx (Pelodiscus) labiatus, Trionyx mortoni Hallowell 1844, Aspidonectes aspilus Cope 1859, Gymnopus aspilus, Fordia africana Gray 1869, Trionyx triunguis rudolfianus Deraniyagala 1948.

Subspecies. – None currently recognized.

Status. – IUCN 2025 Red List Status: Vulnerable (VU A4bcd, assessed 2017), Mediterranean Subpopulation: Critically Endangered (CR, assessed 1996); CITES: Appendix II (2017).