Based on an integration of morphological, molecular and ecological evidences (Delicado et al., 2015), the freshwater gastropod genus Pseudamnicola has been recently split into three different genera: (1) Pseudamnicola s. str. Paulucci, 1878 with around 60 species distributed throughout much of the Mediterranean islands and peninsulas, (2) Corrosella Boeters, 1970 with 13 known species restricted to the Iberian Peninsula and southern France, and (3) Didacus Delicado, Machordom and Ramos, 2015, a monospecific genus whose unique (type) species, Didacus gasulli (Boeters, 1981), was found at several streams from southeastern Spain and Ibiza island.

Unfortunately, authors were not aware that the name Didacus was previously proposed by Collart (1935) to designate a subgenus of the fruit fly genus Dacus Fabricius, 1805 (Diptera: Tephritidae), and afterward only a few taxonomic studies have used Didacus Collart at genus level (e.g. Hering, 1940, 1941, 1952; Narayanan & Rattan, 1954). Consequently, the name proposed for the new spring snail genus Didacus Delicado, Machordom and Ramos, 2015 was not valid when the taxon was described, since it is a junior homonym. Hence, in order to fulfill the requirements of the Art. 23 of the International Code of Zoological Nomenclature, we here propose Diegus nom. nov. as a replacement name for Didacus Delicado, Machordom and Ramos, 2015, named after our good colleague Diego Moreno as mentioned in the original description. Then Diegus gasulli (Boeters, 1981) comb. nov. becomes the valid name of the type species.