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This variety has shorter and wider apices than the nominate variety. Nitzschia gracilis and N. intermedia have narrower apices and more closely spaced striae.

LM scalebar = 10 µm
Nitzschia regula var robusta LM3 Nitzschia regula var robusta LM2 Nitzschia regula var robusta LM1 Nitzschia regula var robusta LM5 Nitzschia regula var robusta LM4
Length Range
50-101 µm
Width Range
5.2-7.4 µm
Striae in 10 µm
23-25

Also compare to

Nitzschia intermedia

Hantzsch

Nitzschia regula

Hust.

Nitzschia gracilis

Hantzsch