Neidium capsulare is more narrow (typically <6.5 µm) and has shorter proximal raphe ends.

Neidium stoermeri has triundulate margins and a broader, more rectangular central area.

LM scalebar = 10 µm
Length Range
37.2-81.3 µm
Width Range
6.5-10.3 µm
Striae in 10 µm
29-33
Neidium bisulcatum LM5
Neidium bisulcatum LM1
Neidium bisulcatum LM2
Neidium bisulcatum LM3
Neidium bisulcatum LM7
Neidium bisulcatum LM4
Neidium bisulcatum LM6
Neidium bisulcatum LM5 Neidium bisulcatum LM1 Neidium bisulcatum LM2 Neidium bisulcatum LM3 Neidium bisulcatum LM7 Neidium bisulcatum LM4 Neidium bisulcatum LM6

Also compare to

Neidium stoermeri

Thomas and Kociolek