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.