An arrangement of Nitzschia rabenhorstii from Burma (now Myanmar). Mounted in Styrax. Prepared by Watson and Sons Ltd. Olympus BHB microscope using 450nm LED light. As well as the arrangement, one was selected for imaging using a 63x Leitz Pl Apo 1.4 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, oblique lighting. 2.5x Nikon CF PL photoeyepiece. 11mm spacer to the camera removed improve field of view. Monochrome converted Nikon d850 camera. 23 images stacked in Zerene (Pmax).
The label says; Trans. striae 45,000 per inch (which is a 564nm pitch based on 25.4mm per inch) and Long. striae 64,000 per inch (397nm pitch). I measured them in ImageJ; 554nm striae (Trans. striae), 411nm puncta (Long. striae). Some variability noted in spacing for both striae and puncta, but pretty close the the values on the slide.
Nitzschia rabenhorstii Grunow, 1880. Original description: Grunow, A. (1880). On some new species of Nitzschia (with notes by Kitton). Journal of the Royal Microscopical Society, series 3, 3(1): 394-397, pl. 12-13. Page 394, Plate 12, Figure 1. Synonymised names: Homoeocladia rabenhorstii (Grunow) Kuntze, 1898. Tryblionella rabenhorstii (Grunow) D.G.Mann, 1990.