Compare

Frustulia quadrisinuata has more undulate margins and protracted apices than F. rexii, F. krammeri, F. amphipleuroides, and F. inculta. F. quadrisinuata has much more broadly rounded apices and robust valves than F. crassinervia. F. quadrisinuata has more broadly rounded apices and undulate valve margins than F. saxonica.

LM scalebar = 10 µm
Frustulia quadrisinuata LM2 Frustulia quadrisinuata LM1 Frustulia quadrisinuata LM5 Frustulia quadrisinuata LM4 Frustulia quadrisinuata LM3
Length Range
58.0-67.0 µm
Width Range
14.0-15.0 µm
Striae in 10 µm
30-31

Frustulia amphipleuroides

(Grunow) A.Cleve 1934

Amphi1 Frustulia amphipleuroides LM1 Amphi4 Amphi5 Amphi3
Length Range
63.0-97.0 µm
Width Range
15.0-16.5 µm
Striae in 10 µm
23-25 in the center, 25-26 at the ends

Frustulia krammeri

Lange-Bert. and Metzeltin 1998

Krammeri128 Krammeri111 Krammeri110 Krammeri109 Krammeri102 Krammeri96
Length Range
68-119 µm
Width Range
18-22 µm
Striae in 10 µm
24-26 in the center, 24-25 at the ends

Frustulia inculta

Siver, Pelczar and Hamilton 2009

Frustulia incluta LM1 Frustulia incluta LM2 Frustulia incluta LM3 Frustulia incluta LM4 Frustulia incluta LM5 Frustulia incluta LM6
Length Range
54-74 µm
Width Range
11.5-14.0 µm
Striae in 10 µm
28-30 in the center valve, 27-28 at the ends

Frustulia rexii

Graeff and Kociolek in Graeff et al. 2012

Frustulia rexii LM1 Frustulia rexii LM2 Frustulia rexii LM3 Frustulia rexii LM4 Frustulia rexii LM5
Length Range
68-111 µm
Width Range
17.5-21.0 µm
Striae in 10 µm
26–28 in the center, 28 at the ends

Frustulia crassinervia

(Bréb.) Lange-Bert. and Krammer 1996

Frustulia crassinverva LM6 Frustulia crassinverva LM5 Frustulia crassinverva LM4 Frustulia crassinverva LM3 Frustulia crassinverva LM2 Frustulia crassinverva LM1
Length Range
34.5-48.0 µm
Width Range
9.0-10.5 µm
Striae in 10 µm
33-35 in the center

Frustulia saxonica

Rabenh. 1850

Frustulia saxonica LM7 Frustulia saxonica LM6 Frustulia saxonica LM5 Frustulia saxonica LM4 Frustulia saxonica LM3 Frustulia saxonica LM2 Frustulia saxonica LM1
Length Range
46.5-87.5 µm
Width Range
12.5-17.5 µm
Striae in 10 µm
30-33