Brazilian snake-necked turtle
|Brazilian snake-necked turtle|
The Brazilian snake-necked turtle (Hydromedusa maximiliani), locally known as Cágado da Serra, is a species of Chelid turtle endemic to eastern and southeastern Brazil. It is one of the smallest Brazilian freshwater turtles reaching a maximum average length of 20 cm. The species prefers streams with sandy and rocky bottoms and clear water in forests above 600 m elevation.
First described as Emys maximiliani by Mikan (1825) it was subsequently moved to the genus Hydromedusa by Wagler (1830) Several other species described later have since been synonymised with this species. There are no recognised subspecies.
The Brazilian Snake-necked turtle is a small species reaching a carapace length of between 10–20 cm with a weight of 120-520g. The carapace of the adult is oval in shape varying in color from dark gray, through to dark or light brown. The plastron is a yellow or cream color. The species has a moderate sized head with a small snout and yellowish jaws, with no barbels on the chin, the iris is black. The dorsal surface of the head, neck and limbs are olive green to gray in color with a lighter cream colored ventral surface.
Distribution and habitat 
The Brazilian snake-necked turtle is endemic to eastern and south-eastern Brazil, in the states of Bahia, Minas Gerais, Espírito Santo, Rio de Janeiro and São Paulo. The distribution is associated with the mountainous Atlantic rainforest. As a generalization it is found in mountain streams above 600m
The species is found in shallow streams from 15–100 cm in depth, with clear, cold water and sandy or rocky substrates. Because of the dense canopy and closed understory of the forests the streams receive little sunlight making basking only possible in gaps along the stream.
Some populations of this species occur within protected areas and are hence afforded some protection from deforestation and pollution which are considered major threats. In regions outside these protected areas the species may be becoming fragmented and may therefore become increasingly vulnerable in the future.
- Mikan, J.C. 1825. Delectus Florae et Faunae Brasiliensis. Fasciculus Quartus. Vindobonae: 6 pp., 6 pls.
- Rhodin, A.G.J., van Dijk, P.P., Iverson, J.B., Shaffer, H.B., Bour, R. 2011. Turtles of the world, 2011 update: Annotated checklist of taxonomy, synonymy, distribution and conservation status. Chelonian Research Monographs 5
- Souza, F.L. and Martins, F.I. 2009. Hydromedusa maximiliani (Mikan, 1825) - Maximilian's Snake-Necked Turtle, Brazilian Snake-Necked Turtle. Chelonian Research Monographs 5(26):1-6
- Wagler, J.G. 1830. Natürliches System der Amphibien, mit vorangehender Classification der Säugthiere und Vögel. München: J.G. Cotta’schen Buchhandlung, 354 pp.
- Iverson, J.B. 1992. A revised checklist with distribution maps of the turtles of the world. Privately Printed, Richmond, Indiana.
- História natural do cágado Hydromedusa maximiliani (Mikan, 1820) no Parque Estadual de Carlos Botelho, SP, região de Mata Atlântica (Reptilia, Testudines, Chelidae). Masters Thesis, Universidade Estadual Paulista, Rio Claro, SP, Brazil.
- Yamashita, C. 1990. Hydromedusa maximiliani. Ecology. Herpetological Review 21:19.