Ptychostomum, Hornschuch, 1824

Spence, John R., 2020, Studies in Austral Bryaceae (Bryopsida) I. New Combinations in Ptychostomum Hornsch. from southern South America, Phytotaxa 437 (2), pp. 60-65 : 62

Preliminary key to Ptychostomum of Tierra del Fuego and Southern Patagonia

1. Leaves uniform in color, red, pink, green to yellow-green, leaf base color not contrasting; limbidium at least partially bistratose, narrow; subalar auriculate inflated group of cells of fertile shoot leaves absent; costa percurrent to short-excurrent ........................ ......................................................................................................................................................................Subgenus Ptychostomum

- Leaves typically green or yellow-green, leaf base typically reddish, contrasting from upper leaf; limbidium unistratose, strong or sometimes weak or rarely absent; pinkish to reddish subalar inflated auriculate group of cells present, at least on leaves of fertile shoots; costa percurrent to long-excurrent in distinct awn................................................................................ Subgenus Cladodium

Note that for many species sexuality is critical and mature capsules are needed as spore size and peristome development are also critical characters. Sterile material of many species cannot be unequivocally identified. Peristome reduction includes cilia shortened or typically absent, reduced endostome processes, and a low basal membrane (<1/2 height of exostome) which is sometimes fused with the exostome.