The headpole of M. constrictum is constricted.

LM scalebar = 10 µm
Length Range
17-80 µm
Width Range
3-4 µm
Meridion circulare LM3
Meridion circulare LM2
Meridion circulare LM1
Meridion circulare LM6
Meridion circulare LM5
Meridion circulare LM3 Meridion circulare LM2 Meridion circulare LM1 Meridion circulare LM6 Meridion circulare LM5

Also compare to

Meridion constrictum

Ralfs 1843