 Hyalella mericilli, SPNOV, and Hyalella meronii, SPNOV. Are two new species of Hyalella from the state of Jalisco, Mexico? These species differ from other Hyalella species in Mexico due to their unique second antennae, which is longer than the total body length and has a peduncle consisting of 14 to 15 articles. Additionally, Hyalella mericilli, SPNOV, has small projections or carini on its pleonites 1 to 2, while Hyalella meronii, SPNOV, lacks these projections. This article was authored by Aurora Marenbicera, Anna Margarita Hermosa Salazar, and Manuel Ayon Parente.