Xoconochcothelphusa, a new genus for Ehecatusa chiapensis (Rodríguez & Smalley, 1972), with notes on Spirothelphusa Pretzmann, 1965 (Crustacea: Decapoda: Pseudothelphusidae).

The species of the genus Ehecatusa Ng & Low, 2010, E. chiapensis (Rodríguez & Smalley, 1972) and E. mixtepensis (Rodríguez & Smalley, in Smalley, 1970), were referred to as incertae sedis in the classification system of the tribe Pseudothelphusini Ortmann, 1897, proposed by Villalobos-Hiriart (2005) and Villalobos & Alvarez(2010) and as members of the subfamily Pseudothelphusinae in the recent phylogenetic proposal by Álvarez et al.

Two new genera and one new species of freshwater crabs of the subfamily Pseudothelphusinae (Decapoda: Brachyura: Pseudothelphusidae) from southwestern Mexico.

Two new genera from the Chimalapas region in eastern Oaxaca, and from Zongolica, Veracruz, Mexico are presented. Mokayathelphusa angelsotoi n. gen.

Revision of the freshwater crabs of the genus Rodríguez & Smalley in Smalley 1970 (Decapoda, Pseudothelphusidae), with the descriptions of two new species.

The freshwater crab genus 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: from Oaxaca and from Veracruz.