The flora of diatoms from Brazil has been studied by several authors from the beginning of the 19(th) up to now. Some of the old lists and descriptions are unknown or have been ignored by Brazilian researchers and the situation of the names cited was not assessed. Here we compiled a list of 101 taxa of diatoms from Brazil registered by Christian Gottfried Ehrenberg during the 19(th) century. We checked the current nomenclatural status of those taxa and lectotypified species from Brazil described by this author. For this, we accessed the Ehrenberg collection in the Museum für Naturkunde, Berlin, Germany, where 11 samples from Brazil studied by Ehrenberg are housed and published in different papers. Using these samples, we found 101 taxa (specific and infraspecific) published by Ehrenberg from Brazil. Five species (Eunotia bidens Ehrenb., Eunotia depressa Ehrenb., Eunotia elephas Ehrenb., Pinnularia microstauron Ehrenb., and Terpsinoe brasiliensis Ehrenb.) were new descriptions and were lectotypified here. The other species cited for Brazil were described initially from other places. However, 23 names were invalid and one illegitimate.
Keywords: Ehrenberg collection; Eunotia; Lectotypification; Pinnularia; Terpsinoe; nomenclatural status.