Catfishes of the genus Ictalurus (Ictaluridae) range geographically from southern Canada to northern Guatemala and Belize. The systematics of this genus remain unresolved, with recent studies suggesting the presence of cryptic diversity. This is the case for a potentially undescribed catfish species distributed in the Nazas River basin, which has been recorded to date as a population of Ictalurus pricei. Recent phylogenetic studies suggest that it represents an independently evolving lineage that is distinct from I. pricei. This study aimed to determine the diagnostic characters that differentiate the Nazas River basin lineage and to describe this lineage as a new taxon. Morphological comparisons were made using meristic and morphometric characters. The study identified useful meristic and morphometric characters for diagnosing Ictalurus nazassp. nov., which differentiate it from I. pricei.

We describe two new species and a new record of stygobitic gastropods from small groundwater-fed springs in Candela, Coahuila, northern Mexico. Phreatomascogos garciasaucedoi n. sp. is described based on shell morphology and is the second species of this formerly monotypic genus. According to the current classification, we have transferred this genus to Cochliopidea. Phreatodrobia candelensis n. sp. is described, and represents the first record of the genus in Mexico extending its known range more than one hundred kilometers to the south. Also found with the new stygosnails was Coahuilix hubbsi Taylor, 1966, which was previously known only as an endemic species from the neighboring Cuatro Ciénegas valley. The reported new subterranean snails are restricted in their distributions to two small water sources only a few meters long which flow directly into a touristic zone with swimming pools and other recreation areas. Using NatureServe Ranking, both new species were assigned as critically imperiled. The very limited distribution and negative anthropogenic impacts within the sites should draw special conservation attention for the reported stygobionts.

This paper describes a new genus and species of stygobitic gastropod from a small groundwater-fed spring in Los Chorros, Coahuila, northern Mexico. Microphreatus saltillensis gen. et sp. nov. is described based on shell morphology, because so far, no living individuals could be obtained. Conchologically, the new genus can be well distinguished from all other subterranean genera by a unique combination of characteristic proto- and teleoconch features. We also reassigned into the new genus Balconorbis coronae (Hershler, 1987), a subterranean snail from Southwestern Texas, so that the new genus consists of two species. One of the most striking features of the new snail is its extremely small shell (about 0.73 mm shell width, 0.36 mm shell height) making the species probably the world’s smallest known freshwater gastropod. Microphreatus saltillensis gen. et sp. nov. is restricted in its distribution to a small water source in a touristic recreation area. This limited distribution and increased anthropogenic impacts make conservation efforts urgently necessary.

El estado de Durango posee condiciones ambientales ideales para incrementar el desarrollo acuícola, pero en los últimos años ha disminuido la producción de esta actividad y descendido a los últimos lugares a nivel nacional. Una de las alternativas para un desarrollo acuícola sustentable en el estado es la aplicación de la Tecnología Biofloc (BFT) en unidades de producción de tilapia. El objetivo del presente estudio fue determinar la aptitud territorial del estado para la producción de tilapia (^{Oreochromis niloticu}s) con BFT. Se realizó una evaluación multicriterio mediante suma ponderada con apoyo de un grupo de expertos. También se generó un mapa de aptitud para la actividad mediante Sistemas de Información Geográfica en el que se establecieron cinco categorías de aptitud: muy baja, baja, media, alta y muy alta. La superficie estimada con aptitud alta y muy alta fue de 50 182 km² para desarrollar la actividad en el estado, las regiones con mayor aptitud se encontraron en el centro este y norte de la entidad, principalmente en la zona semiárida. El 39.67% de la superficie con aptitud alta y muy alta estimada se concentró en los municipios con un Índice de Desarrollo Humano (IDH) Medio o Bajo, lo cual representa un área de oportunidad para incrementar la seguridad alimentaria en estos municipios. Los resultados ayudarán en la identificación de sitios aptos para la implementación de proyectos acuícolas en el estado con enfoque óptimo en el uso del recurso hídrico.