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Meridion anceps is symmetric to the transapical axis, unlike both M circulare and M. circulare var. constrictrum. The striae of M. anceps are more visible (lower stria density) and its costae are thicker and more silicified than in D. tenuis. Meridion anceps has subcapitate to capitate ends, while M. lineare has rounded ends.

LM scalebar = 10 µm
Meridion anceps LM4 Meridion anceps LM6 Meridion anceps LM7 Meridion anceps LM3 Meridion anceps LM2 Meridion anceps LM5 Meridion anceps LM1
Length Range
10.4-45.8 µm
Width Range
5.2-7.0 µm
Striae in 10 µm
18-23

Meridion circulare var. constrictum

(Ralfs) Brun 1880

Kolsow Prairie Sample Edit Meridion circulare var constrictum LM1 Meridion Girdle View Edit Gurtle View Sample 33 Edit Mini Constrictum Edit
Length Range
12-55 µm
Width Range
5-8 µm
Striae in 10 µm
16-20

Meridion circulare

(Grev.) C.Agardh 1831

Meridion circulare LM3 Meridion circulare LM2 Meridion circulare LM1 Meridion circulare LM6 Meridion circulare LM5
Length Range
17-80 µm
Width Range
3-4 µm

Diatoma tenuis

C.Agardh 1812

Diatoma tenuis LM7 Diatoma tenuis LM6 Diatoma tenuis LM4 Diatoma tenuis LM5 Diatoma tenuis LM1 Diatoma tenuis LM3 Diatoma tenuis LM2
Length Range
20-85 µm
Width Range
2.9-4.9 µm
Striae in 10 µm
45-60

Meridion lineare

D.M.Williams 1985

Meridion lineare LM1 Meridion lineare LM2 Meridion lineare LM3 Meridion lineare LM4 Meridion lineare LM5 Meridion lineare LM6 Meridion lineare LM7
Length Range
11-31 µm
Width Range
4.8-8.0 µm
Striae in 10 µm
11-19, mostly 16-18