Taxonomy and valve ultrastructure of new and interesting freshwater fossil diatoms (Bacillariophyta) of Miocene age from the Espanola Formation of New Mexico, USA II. Description of a New Grunowia species with comments on the genus

We describe a new species of the diatom genus Grunowia, G. mannii Kociolek & A.Danz, sp. nov., from a Miocene fossil deposit in New Mexico, USA. The species has wide fibulae, a keel that is off-center externally, with distinct proximal raphe ends, both internally and externally. The species is differentiated from others in the genus in the narrow valves that are swollen and rounded in the center. We formally transfer two species from Nitzschia to Grunowia, making the new combinations, Grunowia constricta (Chen & Zhu) Kociolek & A.Danz, comb. nov. and Grunowia pseudosinuata (Hamilton & Laird) Kociolek & A.Danz, comb. nov. We discuss the distribution of the genus over time and space. This report from the Miocene represents the oldest known member of the genus Grunowia in the fossil record.