Caloneis bacillum is distinguished from C. hyalina by its smaller transverse fascia than in C. hyalina.

LM scalebar = 10 µm
Length Range
8-20 µm
Width Range
3 µm
Striae in 10 µm
25-29
Caloneis bacillum LM1
Caloneis bacillum LM5
Caloneis bacillum LM4
Caloneis bacillum LM2
Caloneis bacillum LM3
Caloneis bacillum LM1 Caloneis bacillum LM5 Caloneis bacillum LM4 Caloneis bacillum LM2 Caloneis bacillum LM3

Also compare to

Caloneis hyalina

Hust. 1937