RESUMEN
The freshwater crab genus Tehuana Rodríguez & Smalley in Smalley, 1970 includes eight species distributed in southeastern Mexico. A recent review of organisms belonging to this genus uncovered new variations in the male gonopod morphology. A phylogenetic analysis based on molecular characters using three genes (H3, 16S, and COI) resulted in the identification of two new species which are described herein: Tehuanaayotzintepecensis sp. nov. from Oaxaca and Tehuanacol sp. nov. from Veracruz. New diagnoses are provided for those species that had very brief descriptions lacking the treatment of important taxonomic characters and an identification key for all the species in the genus is also given. A discussion of the distribution of all the species in Tehuana in the Isthmus of Tehuantepec is presented.
RESUMEN
Two new genera from the Chimalapas region in eastern Oaxaca, and from Zongolica, Veracruz, Mexico are presented. Mokayathelphusa angelsotoi n. gen., n. sp., which is described from Oaxaca, is placed in the subfamily Pseudothelphusinae due to the presence of a caudomarginal projection that ends apically in an ornamented plate. Alvarezius n. gen. is erected to accommodate A. zongolicae (Alvarez, Villalobos & Moreno, 2012) n. comb. This species was described in Pseudothelphusa, but a recent molecular phylogenetic analysis based on partial sequences of three genes (COI, 16S and H3) places this species outside the genus Pseudothelphusa and as a sister lineage to Tehuana. These results in combination with a morphological analysis support the establishment of the new genus.