Cosmioneis hawai’iensis is more broadly rounded and more strongly capitate than C. lundstroemii. Cosmioneis hawai’iensis should also be Cosmioneis capitata which is strongly capitate but narrower and less rounded than C. hawai’iensis. In addition, C. capitata is 11 μm in width, while C. hawai’iensis is 12-15 μm in width.

LM scalebar = 10 µm
Cosmioneis hawaiiensis LM1 Cosmioneis hawaiiensis LM4 Cosmioneis hawaiiensis LM3 Cosmioneis hawaiiensis LM2
Length Range
30-42 µm
Width Range
12-15 µm
Striae in 10 µm
17 in the center, 22 at the ends

Also compare to

Cosmioneis capitata

(Hust.) Lange-Bert.

Cosmioneis lundstroemii

(Cleve) Round, R.M.Crawford and D.G.Mann