Two new species of the genus Mesochra, M. pacifica n. sp. andM. pseudoparva n. sp. are described from Ensenada del Pabellón Lagoon (southeastern Gulf of California, Mexico). Both species are considered as most closely related to M. parva Thomson 1946, although they share some features with M. sewelli Lang 1948. A particular forked structure on the male P3 endopodite of M. pseudoparva n. sp. was found and the homology of this structure is discussed. An updated key to the species in the genus is provided
