Cuatro Cienegas softshell
The Cuatro Ciénegas softshell, also called the black spiny softshell, is a subspecies of the spiny softshell turtle in the family Trionychidae. It is found only in the Cuatro Ciénegas Basin in the Mexican state of Coahuila and it is considered critically endangered by the IUCN. The subspecies, along with its parent species, was formerly classified in the genus Trionyx.