First record of the occurrence of Ceratium furcoides (Levander) Langhans (Dinophyceae) in the Upper Paraná River Floodplain (PR/MS), Brazil

Genus Ceratium Schrank (Dinophyta) is among the plankton species regarded as exotic in Brazil. Ceratium furcoides (Levander) Langhans differ from the remaining best represented species due to its conical apical horn formed with four plates, these three extending to the apex, whereas the fourth plate (4') has its reduced size and does not reach the apex (Popovsky and Pfiester, 1990). The occurrence of this genus is regarded as rare in the country (Oliveira et al., 2011), although the genus dispersion and development in several Brazilian watersheds have already been recorded, indicating an expansion process of geographical distribution. The record of this species in natural environments and in conservation areas is unprecedented and a cause for concern. Although it occurred in low densities and biomass, its monitoring is necessary for a better understanding of the dynamics of its population in order to prevent and manage potential environmental issues.