Distribution and taxonomy of the tropical American Mesocyclops GO Sars, 1914 (Copepoda, Cyclopoida)

The distributional and taxonomic status of the copepod genus Mesocyclops G. O. Sars, 1914, known from tropical America, is revised. Currently, the mai n characters to recognize species (i.e., presence/absence of a spine on the basipodite of the first trunk limb, the presence/absence of teeth-like pro jections on the intercoxal sclerite of the fourth trunk limb, and the shape of the seminal receptacle) have not been strong enough to make a clear, co nfident taxonomic border between morphologically similar species. This is m ost evident in species belonging to the M. thermocyclopoides, the M. meridi anus-brasilianus, and the M. reidae-ellipticus groups. Although some specie s qualify as Pantropical, Neotropical, endemic, and transitional Forms, it is necessary to increase collection efforts and evaluate other morphologica l features in order to establish the taxonomic limits within these intrinca te species groups as well as to determine the real distributional range of each.