Studies carried mainly in the municipality of Nova Xavantina, Mato Grosso State, have lead us to the discovery of several species of Baetidae. While one of them represents a new species of the genus Cloeodes and is herein described, the others represent new records for the state or even for Brazil. The new species, Cloeodes auwe sp. nov., can be differentiated from the other known species of the genus by the following characteristics: body color pattern, long and two-segmented maxillary palp, third segment of labial palp robust and apically truncate, long tarsal claws (0.5 times the length of the respective tarsus), hind wing pads absent, and number of spines on the posterior margin of the third tergite and on the paraproct. Besides this new species, the following taxa of Baetidae were also found: Adebrotus amazonicus, Americabaetis alphus, Apobaetis sp., Aturbina georgei, Baetodes sp., Callibaetis sp.1, Callibaetis sp.2, Camelobaetidius janae, Cryptonympha sp., Harpagobaetis gulosus, Paracloeodes binodulus, Spiritiops silvudus, Waltzoyphius fasciatus, and Zelusia principalis.
Ephemeroptera; Baetidae; Cloeodes auwe sp. nov.; Brazil; West-Central; new records