The transfer of Navicula sovereignae Hustedt to the genus Placoneis Mereschkowsky (Bacillariophyceae)
Keywords:
diatom, taxonomy, ultrastructure, salt marshesAbstract
Morphological, metric and structural features of Navicula sovereignae were studied in detail in salt marsh superfi cial sediment samples from the Patos Lagoon estuary, southern Brazil (31°45’-32°12’S and 52°00’-52°15’W). The species has a broadly elliptical valve, subrostrate ends, narrow sternum and a nodular thickening in the central area. The striae are radiate, areolate, with irregular length at the center of the valve delimiting a subquadrangular central
area. With SEM, in external view, both the central and the polar raphe fi ssures are curved to opposite directions. The helictoglossae are small and prominent at the internal polar fi ssures. The areolae are externally round and internally square to rectangular. All these features allow the transference of Navicula sovereignae to the Placoneis genus, under the new combination Placoneis sovereignae (Hustedt) Torgan & Donadel comb. nov.
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References
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