Compare

Cyclotella atomus is smaller (valves < 8.5 µm in diameter) lacks spines, and marginal fultoportulae are distinct and extend beyond the valve margin. Cyclotella cryptica has coarse striae (6-10 striae in 10 µm). Cyclotella operculata has narrow tapering striae and the valve face is strongly undulate. Cyclotella gamma has coarse striae (5-9 striae in 10 µm) and the valve is strongly transversely undulate.

LM scalebar = 10 µm
Cy Meneghiniana 15624A 09212015 07 Cl Cy Meneghiniana 15640A 10132015 08 Cl Cy Meneghiniana 15540A 09172015 04 Cl Cy Meneghiniana 15615A 08242015 11 Cl Cy Meneghiniana 15596A 09042015 24 Cl Cy Meneghiniana 15540A 09172015 21 Cl
Diameter
6.24-18.12 µm
Striae in 10 µm
7-8 (chambered striae by circumference)

Cyclotella atomus

Hust. 1937

Cyclotella atomus LM2 Cyclotella atomus LM6 Cyclotella atomus LM7 Cyclotella atomus LM9 Cyclotella atomus LM8 Cyclotella atomus LM3
Diameter
5-7.5 µm
Striae in 10 µm
16-18

Cyclotella gamma

Sovereign 1963

Cyclotella Gamma 1 Cyclotella Gamma 2 Cyclotella Gamma 4 Cyclotella Gamma 5 Cyclotella Gamma 6 Cyclotella Gamma 7
Diameter
18.1-48.2 µm
Striae in 10 µm
6-8

Cyclotella distinguenda

Hust. 1927

Cdis29 2 Cdis22 9 Cdis22 9B Cdis19 6 Cdis12 7 Cdis11 8B Cdis9 6
Diameter
7.4-21.9 µm
Striae in 10 µm
12.5-14.7 (by circumference)

Also compare to

Cyclotella cryptica

Reimann, J.C.Lewin and Guillard