Roperia tesselata var. ovata from shell cleanings from Malaya. Spelt ‘tessellata‘ on the slide. Single example on the slide. Recent marine material. Mounted in Styrax Aroclor and dated February [19]71. Prepared by Richard Gosden. Olympus BHB microscope using 450nm LED light. 63x Leitz Pl Apo 1.4 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 32 images stacked in Pmax. I also did a partial stack to accentuate the ‘flame’ edge at the top.
Roperia tesselata var. ovata Heiden 1928. Published in: Heiden, H. & Kolbe, R.W. (1928). Die marinen Diatomeen der Deutschen Südpolar-Expedition 1901-1903. Deutsche Südpolar Expedition 8 (Botany): 447-715. Page 507, no fig.
Roperia tesselata f. ovata (Mann) Voigt, 1949. Original description: (of Roperia tesselata f. ovata Mann, 1925) Mann, A. (1925). Marine Diatoms of the Philippine Islands. United States National Museum, Bulletin 100, 6 (part. 1): 182 pp., 39 pls. Page 143, Plate 31, Figure 3. Just described as Roperia tesselata, however Plate 31, Figure 3 does have the ovoid shape of the one on this slide.
From Mann, 1925: “Only one species of Roperia is known at present. But a variety so marked and constant as to almost deserve specific rank is a broadly ovoid form in which the pseudonodule is invariably located in the narrow end. The rim also is marked diagonally instead of transversely so that the outer marginal line has a fictitious wavy appearance, especially when slightly out of focus. This is the prevailing form in Philippine Islands material. Its deviation from the type is so striking that it is here illustrated.”.