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Abstract
Eunotia grovei Desikachary & Sreelatha and E. marina Schrader were first described from marine diatomaceous sediments of late Eocene to early Oligocene age, from Oamaru, New Zealand. Preliminary light and scanning electron microscope observations of E. grovei and E. marina show striae across the entire valve face, and distal raphe ends present at the apices, while the raphe branches are developed on the valve mantle. A helictoglossa is found at each apex of both valves. This study also confirms the presence of a rimoportula in these Oamaru species. Though these two species are distinct, they are morphologically similar to modern freshwater members of this genus. The marine sample environment and age indicates that E. grovei and E. marina are two of the earliest known eunotioid diatoms and that eunotioid diatoms are older than previously thought.
