FIG. 12 in A study of the morphology and distribution of four Achnanthidium Kütz. species (Bacillariophyta), implications for ecological status assessment, and description of two new European species

FIG. 12. — Achnanthidium neomicrocephalum Lange-Bert. & F.Staab: A, C-F, specimens from Loch Tarff, Scotland; B, G, H, specimens from Llyn y Fan Fawr, Wales; A-H, SEM views of raphe valves; A-C, SEM external views of valves; D, internal view of valve; E, SEM external view of valve centre; F, SEM external view of valve pole; G, SEM internal view of valve centre; H, SEM internal view of valve pole. Scale bars: A-C, 5 µm; D, 3 µm; E-H, 1 µm.