The relationships of Eunotogramma frauenfeldii (Bacillariophyta) I. An account of its structure and description of the new genus Moralesonia Author Williams, David M. 0000-0002-0584-307X Department of Life Sciences, the Natural History Museum, Cromwell Road, London, United Kingdom Author Georgiev, Tsvetoslav https://orcid.org/0009-0009-6036-1012 Department of Life Sciences, the Natural History Museum, Cromwell Road, London, United Kingdom Author Schuster, Tanja M. 0000-0003-0851-3372 Science and Solutions for a Changing Planet DTP, and the Department of Life Sciences, Imperial College London, London, United Kingdom Author Wetzel, Carlos E. 0000-0001-5330-0494 Natural History Museum Vienna, Department of Botany, Herbarium, Vienna, Austria text Plant Ecology and Evolution 2024 2024-07-25 157 3 270 290 journal article 10.5091/plecevo.121829 Moralesonia ? frauenfeldii Figs 9 J , 10 Analysed material. MOZAMBIQUE • East Africa, Ibo; BM Adams TS 457! ( E . Leonard, no. 7); BM Adams TS 459! ( E . Leonard, two specimens ) (figured in Desikachary 1988 : pl. 583, figs 2–4, 6, 7); BM Adams F 16! (ex W . A. Firth) (figured in Desikachary 1988 : pl. 583, fig. 1); BM Adams GC 1450! (ex W . A. Firth) (Fig. 9 J ). MAURITIUS • Rodriguez (Île Rodriguez); Stub NHM I 6 (see Fig. 10 A – F ). Figure 10. Moralesonia sp. , SEM images, specimens from Mauritius, Rodriguez (Île Rodriguez), stub NHM I 6. A . Whole external view of valve, arrows indicate ribs, evident by clear area, extending through to entire mantle, indicating it as part of valve, dividing valve into three ± equal parts, scale bar = 10 µm. B . External view of pole, detail with absence of any pore-field, etc., scale bar = 1 µm. C . Detail of centre of valve, arrows indicating ‘ unadorned’ holes, scale bar = 1 µm. D . Centre of valve with radiating ‘ annulus’ (shown within white box), scale bar = 2 µm. E . External view of pole, with detail of cribra with well-developed, complex volate structure, scale bar = 1 µm. F . Additional external view of pole, with detail of cribra with well-developed, complex volate structure, scale bar = 2 µm. Description. Valves lunate, occasionally fusiform, length 60–65 μm, width 20–25 μm, width ± constant, forming less convex ventral margin. Each valve with two transapical ribs dividing valve into three ± equal parts. Ribs evident externally by clear area, extending through to entire mantle, indicating it as part of valve. Internally raised by 2–3 μm tapering towards mantle edge. Areolae ± round, radiating from eccentric hyaline centre. Rimoportulae absent. Cribra detail not visible or preserved. Girdle unknown.