Abstract
Samples from Christian Gottfried Ehrenberg's Collection were studied for the taxon Navicula affinis Ehrenberg. Since Ehrenberg did not designate a type for Navicula affinis at the place of its first description, eleven localities of his 1843 America publication had to be evaluated. Examination of the micas and samples from these localities, combined with the unpublished notations and original line drawings allowed us to verify that samples from the two localities, Newfoundland (Canada) and Bridgewater (Massachusetts, U.S.A.) contained Navicula affinis; a specimen from Ehrenberg's Newfoundland mica preparation was chosen to serve as lectotype. This study emends the description of the species Neidium affine (Ehrenberg) Pfitzer and the genus Neidium Pfitzer using its type species Neidium affine.