Compare

Rossithidium pusillum is similar to A. rivulare in valve shape, but the terminal raphe fissures of R. pusillum are not distinct. Achnanthidium minutissimum valves are more linear or linear-elliptical in shape. Rossithidium nodosum has coarser striae but lacks the two irregularly broad striae in the center of the raphe valve.

LM scalebar = 10 µm
Rossithidium pusillum LM6 Rossithidium pusillum LM8 Rossithidium pusillum LM10 Rossithidium pusillum LM2 Rossithidium pusillum LM4 Rossithidium pusillum LM12
Length Range
10–16 µm
Width Range
3.1-4.1 µm
Striae in 10 µm
20-24

Achnanthidium rivulare

Potapova and Ponader 2004

Achnanthidium rivulare LM4 Achnanthidium rivulare LM5 Achnanthidium rivulare LM3 Achnanthidium rivulare LM2 Achnanthidium rivulare LM1
Length Range
5.4-23.8 µm
Width Range
2.6-4.4 µm
Striae in 10 µm
19-25 in the middle of raphe valve, 19-28 in the middle of the rapheless valve

Achnanthidium minutissimum

(Kütz.) Czarn. 1994

Achnanthidium minutissimum LM4 Achnanthidium minutissimum LM3 Achnanthidium minutissimum LM7 Achnanthidium minutissimum LM2 Achnanthidium minutissimum LM6 Achnanthidium minutissimum LM1 Achnanthidium minutissimum LM5
Length Range
5.6-20.8 µm
Width Range
1.5-3.3 µm
Striae in 10 µm
25-35

Rossithidium nodosum

(A.Cleve) Aboal 2003

Rossithidium nodosum LM10 Rossithidium nodosum LM8 Rossithidium nodosum LM2 Rossithidium nodosum LM6 Rossithidium nodosum LM4
Length Range
9.0-11.9 µm
Width Range
2.9-3.3 µm
Striae in 10 µm
16-20