Guide to Achnanthidium subhudsonis var. kraeuselii
Credit: Sarah Spaulding, Marina Potapova
- Valves small, narrow, lanceolate
- Striae radiate
- Raphe valve with striae more widely spaced at center
- Rapheless valve with striae more evenly spaced
Valves are narrow and lanceolate. The raphe valve has a lanceolate axial area becoming narrow at the apices. Striae are radiate and more broadly spaced at the central valve than near the ends. The rapheless valve has a more narrow lanceolate axial area than the raphe valve. The axial area of the rapheless valve is asymmetrically bent near the apices in many specimens. Striae are radiate on the rapheless valve, but less so than on the raphe valve. The striae are composed of punctate areolae.