New Combinations and Type Analysis ofChamaepinnulariaSpecies (Bacillariophyceae) from Aerial Habitats

Abstract

We detail under light and scanning electron microscopy the type materials of three poorly known diatom species first described by Hustedt from aerial habitats in Germany. Navicula parsura Hustedt (synonym: N. obscura Hustedt), N. obsoleta Hustedt, and N. evanida Hustedt type materials were observed and compared with populations from Luxembourg. Ultrastructural analysis revealed the presence of striae composed by areolae occluded externally by hymenes and a silica line at the valve face-mantle junction along the apical plane. These taxa also present a naviculoid raphe, which besides overall valve outline, conforms to the genus Chamaepinnularia Lange-Bertalot et Krammer. Therefore, we propose two new combinations: Chamaepinnularia obsoleta (Hustedt) C.E. Wetzel et Ector comb. nov. and C. parsura (Hustedt) C.E. Wetzel et Ector comb. nov. Excepting C. evanida (Hustedt) Lange-Bertalot, which is often observed in European rivers and already placed in the genus Chamaepinnularia, the remaining two taxa are poorly known and autecological data are scarce. Our results suggest that these species, present in stream drift during flood events, might partially derive from near-stream riparian or upslope terrestrial habitats. In addition, based on literature data, three new combinations are also proposed.