Morphology and Taxonomy of Marine Benthic Diatoms (12), Genus Seminavis (Naviculaceae, Naviculales) (Part 3)

Abstract

The fine structure of a brackish and freshwater benthic diatom Seminavis strigosa (Hustedt) Danielidis & Economou-Amilli was examined using light and scanning electron microscopy. The mature cingulum consists of three non-areolae bands with alternating orientation: a broad valvocopula, a short segmental 2nd band, and a narrow 3rd band. Based on the morphological re-examination and considering previous studies, we propose here the following new taxonomic characteristics that define this genus: i) of the two chloroplasts, the ventral chloroplast is rod-like and the dorsal one is plate-like; ii) the distal raphe ends internally terminate in short helictoglossae; and iii) an accessory rib is developed on the inner surface of the ventral axial area. (Continued from J. Jpn. Bot. 98: 13–18, 2023)