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Fragilariforma constrica f. stricta is smaller and lacks undulate margins. Fragilariforma constricta var. trinodis and Fragilariforma polygonata have tri-undulate margins. Fragilariforma hungarica var. tumida has a single, large central undulation.

LM scalebar = 10 µm
Frconstricta 747 40B Frconstricta 863 39  Brant1098B Frconstricta 811 37  Net Lake Frconstricta 602 33B Frconstricta 504 27 Frconstricta 455 24B Frconstricta 490 22B
Length Range
22-40 µm
Width Range
3.7-5.9 µm
Striae in 10 µm
16-24

Fragilariforma polygonata

(A.Cleve) Kingston, Sherwood and Bengtsson 2001

Frpolygonata 544 27 2 Frpolygonata 520 26 Frpolygonata 456 22 8 Frpolygonata 446 22 3 Frpolygonata 595 19 8
Length Range
22.1-30.2 µm
Width Range
9.8-10.5 µm
Striae in 10 µm
19-20

Also compare to

Fragilariforma constricta f. stricta

(A.Cleve) Poulin in Hamilton

Fragilariforma constricta var. trinodis

(Hust.) Hamilton

Fragilariforma hungarica var. tumida

(A.Cleve) Hamilton