EN
During a parasitological survey of the reef ichthyofauna in the Caribbean coast of Mexico, parasitic siphonostomatoid copepods were obtained from the white grunt Haemulon plumierii (Lacepède) and the blue striped grunt H. sciurus (Shaw). Caligus haemulonis Krøyer, 1863 has been recorded from both species of Haemulon in the Northwestern Tropical Atlantic, but it is reported herein for the first time from Mexico. The prevalence and intensity of infection of C. haemulonis has not previously been evaluated in the Caribbean grunts; during this survey, prevalence was highest in H. sciurus; values are similar to those found in other haemulids. Lernanthropus chacchi sp. nov. can be distinguished from its closest congener, L. rathbuni Wilson, 1922, by its female having a dorsal plate covering the entire urosome and the lack of lateral notches at the base of the modified third legs, the male has relatively longer third legs, different body proportions and ornamentation of the first and second legs. This is the third species of Lernanthropus known from reef grunts in the Caribbean and the second species of the genus described from Mexican waters. The infection prevalence of the new species on H. sciurus (24%) was higher than that known for L. rathbuni from other haemulids. Taxonomic illustrations of females and males of both species are also provided. Other crustacean ectoparasites included the copepod Hatschekia spp. and praniza larvae of a gnathid isopod.