1. Medial and upper leaf cells with 1-4 papillae per cell, papillae tall, centered over lumen  ....... 2 (Hedwigia and Pseudobraunia)

Cross section of leaf showing papillae centered over cell lumen (From Biasuso, 2007)

Upper leaf cells with marginal papillae arching over cell lumen (From De Luna & Gómez-Velasco, 2008)

2. Seta (0.5) 0.8–1.0 (1.2) mm, capsules immersed, turbinate-urceolate, mouth wide; operculum low, planoconvex, rostrum small mammillate; leaf acumen hyaline-white; perichaetial leaf margins ciliate   ......... Hedwigia

2. Seta (4) 6–7 (10) mm, capsules exserted, turbinate, mouth wide; operculum high, conic, short rostrate; perichaetial leaf margins entire .......Pseudobraunia

Hedwigia detonsa, California (US). Photo by M. Lüth

3. Capsules immersed, turbinate-urceolate, subglobose, mouth wide; operculum low, planoconvex, rostrum small mammillate; perichaetial leaf margins entire, undulate; seta (0.8) 1.0–3.0 (4.0) mm   ......... .......Hedwigidium

Hedwigidium imberbe, Veracruz (Mex).

3. Capsules exserted, cylindric, ellipsoid, ovate, turbinate, mouth wide or narrow; operculum conic, long rostrate; perichaetial leaf margins entire, not undulate; seta (4) 7–12 (17) mm   ............. Braunia

Braunia plicata, Bolivia.

FROM THE ONLINE VERSION OF CENTRAL AMERICAN MOSSES

Hedwigia

Discussion:

Hedwigia has often been considered a monospecific genus (see Hedenäs 1994 and Buck & Norris 1996), but presently it contains at least five taxa (H. ciliata (Hedw.) P. Beauv., H. ciliata var. leucophaea Bruch & Schimp. in B.S.G., H. detonsa (M. Howe) W. R. Buck & D. H. Norris, H. nivalis (Müll. Hal.) Mitt., and H. stellata Hedenäs). The genus lacks a stem central strand, paraphyllia, leaf costa, and peristome. Its primary, creeping stems are so poorly developed they are often difficult to demonstrate, and its secondary stems and branches rarely produce stolons. Hedwigia characteristically has broadly ovate, acuminate leaves that end in broad, hyaline acumina, densely papillose leaf cells, immersed, cupulate capsules, and cryptoporic stomata. Although H. detonsa has entire perichaetial leaves, all other species of Hedwigia have long-ciliate perichaetial leaves.

Hedwigidium and Hedwigia have immersed capsules, and their gametophytes are very similar.
Hedwigidium differs from Hedwigia in often having stoloniferous gametophytes, concolorous or narrowly hair-pointed leaf apices, longer, broadly oblong to subglobose, furrowed capsules, and phaneroporic stomata.

Braunia is immediately separated from Hedwigia by its long-exserted capsules. In Central America,
the gametophytes of Braunia can also be distinguished from Hedwigia by their concolorous or
narrowly hair-pointed leaf apices. There are, however, some Braunia species outside the region (i.e., B. diaphana (Müll. Hal.) A. Jaeger) that have long, broad, hyaline leaf acumina identical to those of Hedwigia. The gametophytes of Braunia, like those of Hedwigidium, often have stoloniferous shoots from its secondary stems and branches, and this feature can be used to separate Braunia from Hedwigia. In addition, the leaves of Braunia are often plicate, while those of Hedwigia are smooth.

Braunia

Discussion:
Braunia is a genus of 23 (Crosby et al. 2000) mostly Southern Hemispheric species. Although De
Luna (1992) recognized only 16 species of Braunia, no synonymy was included with his species list. The genus is distinguished from other Central American Hedwigiaceae genera by its long setae; Hedwigia and Hedwigidium have immersed capsules. The leaves of Hedwigia are also distinguished from those of Braunia in having very broad, hyaline hair-points and cells with high, often branched papillae. Hedwigidium, on the other hand, is gametophytically so close to Braunia that collections without sporophytes are almost impossible to place to genus.