FIG. 18 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. 18. — Achnanthidium lacuslustense sp. nov., specimens from Lustsee, Germany: A, SEM external view of raphe valve; B, SEM internal view of raphe valve; C, D, SEM external views of frustules in girdle view; E, SEM external view of rapheless valve; F, SEM internal view of rapheless valve; G, SEM internal view of centre of rapheless valve; H, SEM internal view of pole of rapheless valve. Scale bars: A-F, 5 µm; G, H, 3 µm.