Fragilaria pinnata var. subcapitata Frenguelli, typification and current taxonomic status

Type material of Fragilaria pinnata var. subcapitata Frenguelli, a diatom originally described from diatomite in northern Chile, has been examined using light and scanning electron microscopy. Its valve morphology is described and comparisons to the original description, additional reports and closely related taxa are provided. Morphological features of this taxon confirm its transfer to the genus Staurosirella as S. subcapitata. Since Frenguelli did not formally designate a type, we selected one of the examined specimens as lectotype.