FIGURES 399–402. SEM micrographs of Achnanthidium duriense Novais & Ector, sp. nov. from A-do-Bispo, Torto River, Douro basin, 18-08-2007 (129/07). 399. Raphe valve in girdle view, with the row of slit-like areolae on the mantle clearly visible. 400. Detail of a raphe valve in external view, with the proximal raphe ends drop-shaped and slightly deflected unilaterally. 401. Detail of a raphe valve in external view. 402. Detail of a rapheless valve in external view, with the rounded areolae on the valve and the slit-like areolae on the mantle, including the apex. Scale bars = 1 μm.

Published as part of Novais, Maria Helena, Jüttner, Ingrid, Vijver, Bart Van De, Morais, Maria Manuela, Hoffmann, Lucien & Ector, Luc, 2015, Morphological variability within the Achnanthidium minutissimum species complex (Bacillariophyta): comparison between the type material of Achnanthes minutissima and related taxa, and new freshwater Achnanthidium species from Portugal, pp. 101-139 in Phytotaxa 224 (2) on page 128, DOI: 10.11646/phytotaxa.224.2.1, http://zenodo.org/record/13636829