Frustulia esandalliae is one of only a handful of Frustulia species with capitate apices. It is easily separated from F. amosseana and F. spicula by its larger size. It is very similar in size and shape to F. alfinitosilviae but has a wider, more elliptic and less linear central area (3.0-5.1 μm wide, not 1.5-2.0 μm wide) and more closely spaced areolae (24-26 in 10 μm, not 17-20 in 10 μm).

LM scalebar = 10 µm
Frustulia esandalliae LM1 Frustulia esandalliae LM2 Frustulia esandalliae LM3 Frustulia esandalliae LM4 Frustulia esandalliae LM5 Frustulia esandalliae LM6 Frustulia esandalliae LM7
Length Range
67.2-113.0 µm
Width Range
13.7-18.5 µm
Striae in 10 µm

Frustulia amosseana

Lange-Bert. in Rumrich et al. 2000

Frustulia amosseana LM1 Frustulia amosseana LM2 Frustulia amosseana LM3 Frustulia amosseana LM4 Frustulia amosseana LM5  Frustulia amosseana LM6 Frustulia amosseana LM7
Length Range
28.1-61.3 µm
Width Range
5.8-8.3 µm
Striae in 10 µm

Also compare to

Frustulia alfinitosilviae

Lange-Bert. 2001

Frustulia spicula

Amossé 1932