Cocconeis placentula has much finer areolae and striae on the rapheless valve and the raphe valve has a smooth submarginal hyaline area.

Cocconeis disculus also has large coarse areolae on the rapheless valve, but the raphe valve has a smooth submarginal hyaline area. Cocconeis disculus has not yet been confirmed in streams and rivers of California.

LM scalebar = 10 µm
Cocconeis Cascadensis Lm08 Cocconeis Cascadensis Lm04 Cocconeis Cascadensis Lm02 Cocconeis Cascadensis Lm07 Cocconeis Cascadensis Lm03 Cocconeis Cascadensis Lm06 Cocconeis Cascadensis Lm05
Length Range
15.7-40 µm
Width Range
8.7-22 µm
Striae in 10 µm
Raphe valve 15-18.5, rapheless valve 7–12

Cocconeis placentula sensu lato

Ehrenb. 1838

Cocconeis placentula LM1 Gc109658  Mo000285  Ccplac2 Ed Gc109658  Mo000285  Ccplac3 Ed Gc100282  Gs016353  Cclplac1 Ed Gc109658  Mo000285  Ccplac1 Ed Gc108381  Nx000030  Ccpseudol1 Ed Gc100282  Gs016353  Cclplac2 Ed
Length Range
9-68 µm
Width Range
7-32 µm
Striae in 10 µm
20-24 on raphe valve, 15-25 on rapheless valve

Cocconeis coreana

R. Jahn and B.M. Suh 2020

Cocconeis coreana auxospore Cocconeis coreana LM3 Cocconeis coreana LM6 Cocconeis coreana LM2 Cocconeis coreana LM16 Cocconeis coreana LM15 Cocconeis coreana LM1
Length Range
21-58 µm
Width Range
11.5-36.6 µm
Striae in 10 µm
18-24 raphe valve, 18-24 rapheless valve

Cocconeis czarneckii

Stancheva, D.L.Mora and R.Jahn 2022

Cocconeis czarneckii LM4 Cocconeis czarneckii LM1 Cocconeis czarneckii LM5 Cocconeis czarneckii LM6 Cocconeis czarneckii LM2 Cocconeis czarneckii LM3
Length Range
17.7-51 µm
Width Range
11.3-37.9 µm
Striae in 10 µm
Raphe valve 18-30, rapheless valve 20-26

Also compare to

Cocconeis disculus

BioData Reference
Krammer and Lange-Bertalot 2/4 PL 56 Fig1-13