First record of Reimerothrix floridensis (Fragilariaceae: Bacillariophyta) for Mexico.

Reimerothrix floridensis is part of a group of arcuate-shaped diatoms that are generally confused with Cylindrotheca closterium, Psammosynedra closterioides and Nitzschia longissima var. reverse. In this work presents the first record of the arcuate diatom Reimerothrix floridensis, collected in Dzilam de Bravo (north coast of the Yucatan Peninsula) in the southern tip of the Gulf of Mexico. This find was carried out within the framework of the identification of the diatom species that formed a proliferation of phytoplankton raised on the coasts of the Yucatan Peninsula during 2011, and where C. closterium and N. longissima var. Reversa were dominant species. The characteristics of R. floridensis coincide with the original description of the species, except for the areolas associated with the sternum. Since this species had only been recorded in Florida Bay, your observation in Mexico on the north coast of the Yucatan Peninsula represents its southernmost record, which extends the geographic range of this species. On the other hand, because the observation of R. floridensis was carried out During the presence of a proliferation of C. closterium and N. longissima, species with which it is generally confused, the importance of making careful taxonomic determinations accompanied by detailed descriptions that give certainty to ecological studies.