Spores smooth or tuberculate. Capsule contents not differentiating into spores is not uncommon in variants of M. starckeanum indicating the possibility of occasional hybridization. Anacalypta starckeana var. Stem leaves very shortly mucronate. Capsule stegocarpous, peristome absent or rudimentary.
Spores smooth or tuberculate.
Microbryum starckeanum var. Pottia fosbergii Bartr. Stem leaves mucronate to short-awned. Capsule cleistocarpous, peristome rarely differentiated internally, operculum absent or occasionally weakly differentiated. Spores both tuberculate and papillose.