A remarkable new genus and species of subterranean freshwater snail from a recently dried-up spring of Viesca, Coahuila, Northern Mexico

This paper describes a new genus and species of subterranean gastropod from a karstic region near Viesca, Coahuila in northern Mexico. Shells of Phreatoviesca spinosagen. nov. et sp. nov. were found in spring-deposited sediments near the outlet of a cave that dried up in the late 20th century. The new genus can be primarily distinguished conchologically from other phreatic genera by three remarkable characteristics: (i) prominent open coiling of the last whorl, (ii) shovel-shaped spine ornamentations on the teleoconch, and (iii) a coarsely honeycomb-like pitted protoconch structure. Since only dry shells were found, the new species could already be extinct. However, in view of the relative recent drying up of the spring, we consider that Phreatoviesca spinosa is possibly extant in the aquifers in or adjacent to the Viesca region.