Morphological observations on Vikingea gibbocalyx (Brun) Witkowski, Lange-Bertalot Metzeltin (Bacillariophyta)
Vande Vijver, Bart; Riaux-Gobin, Catherine; Compère, Pierre
Light (LM) and scanning electron (SEM) microscope observations of Vikingea gibbocalyx (Brun) Witkowski, Lange-Bertalot et Metzeltin, from coral sands off Réunion (Indian Ocean), are presented. The species is illustrated with a particular focus on new, or previously poorly documented, morphological details such as the raised external ridges, the structure of the girdle and the structure of the areolae with typical disc-like coverings. In the middle of the valve, near the margin, two central-marginal circular structures are observed. The fine architecture of the central-marginal circular structures and the areolae are examined. The biogeography of the taxon is discussed taking into account all observations in the literature.