Navicula freesei is similar to many lanceolate Navicula. The central area of N. radiosa is more symmetric and round. In addition, in N. freesei the areola density is lower, the axial area is linear and wider, and the proximal raphe ends are tear-drop shaped. Comparison can be made with N. hasta var. gracilis and N. peregrina var. peregrinoides, but these taxa differ in striae orientation, shape of the central area and valve size.

LM scalebar = 10 µm
Navicula freesei LM2 Navicula freesei LM1 Navicula freesei LM4 Navicula freesei LM3
Length Range
61.8–77.1 µm
Width Range
13.3–15.2 µm
Striae in 10 µm

Navicula radiosa

Kütz. 1844

Navicula radiosa LM2 Navicula radiosa LM4 Navicula radiosa LM1 Navicula radiosa LM6 Navicula radiosa LM7 Navicula radiosa LM3 Navicula radiosa LM5
Length Range
52-105 µm
Width Range
8.8-11.2 µm
Striae in 10 µm

Also compare to

Navicula hasta var. gracilis


Navicula peregrina var. peregrinoides

(A.Cleve in Halden) A.Cleve