Compare Rossithidium petersenii
Compare
Rossithidium petersenii differs from R. pusillum by having larger valves, a higher stria density, and a large rectangular or elliptical central area on the raphe valve and a narrowly rhomboid axial area on the rapheless valve. Rossithidium petersenii can be confused with frequently co-occurring Achnanthidium kranzii, that also has a large central area on the raphe valve, but can be distinguished from A. kranzii by wider and more linear valves, the narrowly rhomboid axial area on the rapheless valve, and the absence of terminal raphe fissures.
LM scalebar = 10 µm
Length Range
13-18.5 µm
13-18.5 µm
Width Range
3.5-4.5 µm
3.5-4.5 µm
Striae in 10 µm
32-36
32-36
Achnanthidium kranzii
Length Range
8-20 µm
8-20 µm
Width Range
2.8-3.8 µm
2.8-3.8 µm
Striae in 10 µm
24-30 in the center valve, up to 40 at the ends
24-30 in the center valve, up to 40 at the ends
