Both M. alansmithii and M. hohii have rimoportulae that are positioned mid-valve and subcapiate apices. Meridion hohii has shorter and wider valves than M. alansmithii. In M. circulare var. constrictum, the rimoportula is positioned at, or near, the head pole.

LM scalebar = 10 µm
Mealan New 1 Mealan New 2 Mealan New 3 Mealan New 4 Mealan New 7 Mealan New 5 Mealan New 6
Length Range
20-100 µm
Width Range
3.5-5.5 µm
Striae in 10 µm

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

Also compare to

Meridion hohii

Rhode, Pappas and Stoermer 2001