New genus, two new species and new records of subterranean freshwater snails (Caenogastropoda; Cochliopidae and Lithoglyphidae) from Coahuila and Durango, Northern Mexico

Shells of Balconorbis sabinasense sp. n. and Coahuilix parrasense Czaja, Estrada-Rodríguez, Romero-Méndez, Ávila-Rodríguez, Meza-Sánchez & Covich, 2017. 12–14 B. sabinasense n. sp., holotype, UJMC 410. 15–18 Paratype 1, UJMC 411. 19–21 C. parrasense, UJMC 418, from Nazas River, Durango. 22, 23 C. parrasense, fossil specimen from Parras de la Fuente, Coahuila, holotype, UJMC-320, from Czaja et al. 2017c, Fig. 4A, C. Scale bar: 0.5 mm (12–14, 19–23).