The New World genus Mycotretus Lacordaire, 1842 (Erotylidae: Erotylinae: Tritomini) is the second most speciose genus within Erotylidae and is found mainly in the Neotropical region. Currently, the genus includes 231 available names, of which 204 are valid. Accurate species identification is hampered by the lack of taxonomic revisions, identification keys or an illustrated catalogue for Mycotretus. To correct this problem and to allow further studies, the objective in this paper is to provide an illustrated catalogue for Mycotretus and propose some taxonomic acts promoting taxonomic stability within the genus. The present catalogue is the result of more than six years of morphological studies and careful comparisons of specimens, including research in several scientific collections throughout America and Europe, searching for identified specimens and types of available names of Mycotretus. The historical literature was examined and all available names listed in the catalogue of Blackwelder (1945) are included here, along with updated information from the catalogue of Alvarenga (1994). Our main results are: (i) examination of types of 216 former available names within Mycotretus, including 74 types previously not examined or not located by Alvarenga (1994); (ii) lectotype designations for 143 available names of Mycotretus; (iii) proposal of 41 new synonyms and three new combinations; (iv) the number of valid species of Mycotretus is reduced from 204 to 174; (v) plates providing images (most of them types) of specimens representing most available names within Mycotretus. The present work is the first major step towards a nomenclatural stability that will allow further revisionary and phylogenetic studies on Mycotretus.