Melosira varians has much smaller cells with a thinner cell wall and scattered rimoportulae. Melosira undulata has a circular inner outline of the mantle, areolae rows on the valve face are radiate rather than spiral, and the small central area lacks areolae.

LM scalebar = 10 µm
Melosira normannii LM1 Melosira normannii LM2 Melosira normanii LM3 Melosira normanii LM6 Melosira normanii LM4 Melosira normanii LM5
33.9-62.9 µm
Width Range
13.5-21.7 µm

Melosira undulata

(Ehrenb.) Kütz. 1844

Melosira undulata LM4 Melosira undulata LM3 Melosira undulata LM1 Melosira undulata LM2 Melosira undulata LM5 Melosira undulata LM6 Melosira undulata LM7
30-81 µm
Width Range
28-47 µm
Striae in 10 µm

Melosira varians

C.Agardh 1827

Melosira varians LM6 Melosira varians LM1 Melosira varians LM2 Melosira varians LM4 Melosira varians LM7 Melosira varians LM3
6-30 µm
Width Range
5-15 µm