Although similar in shape Fallacia pygmaea is much larger and has a clear lyrate area, as opposed to the microcostae in M. krasskei. Microcostatus naumannii is larger than M. krasskei, has coarser striae and subrostrate ends.

LM scalebar = 10 µm
Mic511 Microcostatus krasskei LM3 Mic311 Mic411 Microcostatus krasskei LM6 Mic11
Length Range
8-9 µm
Width Range
3-3.8 µm
Striae in 10 µm

Fallacia pygmaea

(Kütz.) Stickle and D.G.Mann in Round et al. 1990

Fallacia pygmaea LM2 Fallacia pygmaea LM5 Fallacia pygmaea LM1 Fallacia pygmaea LM4 Fallacia pygmaea LM6 Fallacia pygmaea LM3
Length Range
17-38 µm
Width Range
8-13 µm
Striae in 10 µm
24-28 in the center, more fine towards the apices, 32-34

Also compare to

Microcostatus naumannii

(Hust.) Lange-Bert.