Guerramontesia M.J. Cano, J.A. Jiménez, M.T. Gallego & J.F. Jiménez is a monotypic genus known from Argentina and Bolivia. It is distinct from other genera of the Pottiaceae by a combination of characters: absence of central strand in the stem, lingulate unbordered leaves with yellow KOH colour reaction, costa at midleaf with one band of dorsal stereids, (1)2-3 guide cells layers, absence of hydroids, and sporophyte with peristome of 16 variously cleft, occasionally perforate, coarsely papillose, short and straight teeth.