Compare

Caloneis amphisbaena has capitate apices, while Caloneis amphisbaena var. subsalina has apiculate apices.

LM scalebar = 10 µm
Caloneis Amphisbaena  Ill2014 037 7 Caloneis Amphisbaena  Ill2014 037 9 Caloneis Amphisbaena  Ill2014 037 2 Caloneis Amphisbaena  Ill2014 037 3 Caloneis Amphisbaena  Ill2014 037 5 Caloneis Amphisbaena  Ill2014 037 10
Length Range
58.6-77.0 µm
Width Range
21.3-26.4 µm
Striae in 10 µm
15-17

Also compare to

Caloneis amphisbaena var. subsalina

(Donkin) Cleve