Studies on the genera Gyrosigma and Pleurosigma (Bacillariophyceae) - Gyrosigma reversum (Gregory) Hendey and G. naja (Meister) Sterrenburg, nov comb.

The transfer of Pleurosigma reversum Gregory to Gyrosigma by Hendey was tax onomically and formally correct. Gyrosigma reversum Ricard bears an illegit imate name; its identity is unclear. New observations of Gregory's taxon fo rm the basis of an emended species description. Pleurosigma naja Meister ha s a similar valve contour and also inflated ends but is an independent spec ies. A new combination, Gyrosigma naja (Meister) Sterrenburg is proposed he re, with G. spathulatum Ricard as a synonym.