Diatoms of North AmericaDiatoms of North America
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Compare Aulacoseira ambigua

(Grunow) Simonsen 1979

Compare

Aulacoseira ambigua differs from other species of the genus by the hollow ringleiste. In cell dimensions and proportions it is similar to A. subarctica and A. granulata.

Aulacoseira granulata and A. granulata var. angustissima can be easily distinguished by their long separation spines and large square mantle areolae.

Aulacoseira subarctica has large spines originating from two pervalvar costae on both separation and linking valves, while A. ambigua has small bifurcate linking spines originating from each pervalvar costa. It may be difficult to distinguish separation valves of A. subarctica and A. ambigua because the pervalvar costae in valves of A. ambigua often coalesce at a distance to the valve face. As a result, the separation spines appear to originate from two costae as in A. subarctica. Separation spines of A. ambigua are, however, much thinner than those of A. subarctica.

LM scalebar = 10 µm
Aulacoseira ambigua LM5 Aulacoseira ambigua LM6 Aulacoseira ambigua LM3 Aulacoseira ambigua LM4 Aulacoseira ambigua LM7 Aulacoseira ambigua LM1 Aulacoseira ambigua LM2
Diameter
3-12 µm
Width Range
5-15 µm
Striae in 10 µm
17-22

Aulacoseira subarctica

(O.Müll.) E.Y.Haw. 1990

Aulacoseira subarctica LM2 Aulacoseira subarctica LM3 Aulacoseira subarctica LM1 Aulacoseira subarctica LM4 Aulacoseira subarctica LM5 Aulacoseira subarctica LM6 Aulacoseira subarctica LM7
Diameter
3-14 µm
Width Range
2.5-14 µm
Striae in 10 µm
15-22

Aulacoseira granulata

(Ehrenb.) Simonsen 1979

Aulacoseira granulata LM1 Aulacoseira granulata LM2 Aulacoseira granulata LM3 Aulacoseira granulata LM4 Aulacoseira granulata LM5 Aulacoseira granulata LM6
Diameter
4-17 µm
Width Range
4-20 µm
Striae in 10 µm
8-18

Aulacoseira granulata var. angustissima

(O.Müll.) Simonsen 1979

Aulacoseria granulata var. angustissima LM1 Aulacoseria granulata var. angustissima LM2 Aulacoseria granulata var. angustissima LM7 Aulacoseria granulata var. angustissima LM6 Aulacoseria granulata var. angustissima LM3 Aulacoseria granulata var. angustissima LM4 Aulacoseria granulata var. angustissima LM5
Diameter
2.5-4 µm
Width Range
8-20 µm
Striae in 10 µm
10-20