The Pottiaceae are a large and exceedingly complex family of worldwide distribution. Members of the family usually grow on soil or rock, especially on calcareous substrates, in dry places. Due to its large size and tremendous variability the family is difficult to characterize. In a broad sense, gametophytes in the Pottiaceae are usually small, have contorted leaves, with entire or dentate margins, and leaf cells that are short, pluripapillose above but enlarged, hyaline and smooth below. The costa in the Pottiaceae is always single and well-developed. Features of its internal structure, as well as the internal structure of the stem, are important in the taxonomy of the family. Proper identification of Pottiaceae genera and species requires making leaf and stem cross-sections. Sporophytically, the family usually has elongate, twisted setae, erect-cylindrical capsules, and 16–32 filiform peristome teeth that are borne on a basal membrane. When the family is considered on a worldwide basis, however, the species seem to exhibit every conceivable variation and combination of variations in gametophytic and sporophytic features.
There have been many attempts at subdividing this complex family and these varying classifications are sometimes radically different in their disposition of genera. Due to the reticulating nature of character variation in the Pottiaceae these classifications rely upon a subjective weighting of the various features of the group. For example, the genus Weissia is often aligned with Trichostomum (Crum & Anderson 1981, Saito 1975, Zander 1994a) when the features of leaf shape, a costa with two stereid bands and the presence in some Trichostomum species of involute leaf margins are emphasized. Zander (1993), however, recently placed the genus in a group nomenclaturally centered around Hyophila by emphasizing the involute leaf margins of Weissia and the presence in a few Weissia species of leaf cells that are ventrally bulging but dorsally flat.
Useful regional treatments of the Pottiaceae have been published by Saito (1975), Crum & Anderson (1981), Norris & Koponen (1989), and Sharp et al. (1994). Zander’s (1993) monumental generic treatment of the family is an essential work for anyone attempting to understand the family.
Chenia leptophylla (C. Müll.) Zand. was recently collected in Costa Rica (Alajuela: Holz & Schäfer-Verwimp CR99-1339, GOET; Heredia: Holz & Schäfer-Verwimp CR99-1422, GOET; San José: Holz & Schäfer-Verwimp CR99-1339, GOET). The species grows on bare soil in weedy places and is widely distributed throughout the world. It is a small moss with spathulate leaves having apiculate apices, dentate upper leaf margins, large, smooth leaf cells, no costal stereid cells, and immersed, cleistocarpous sporophytes. The species commonly has rhizoidal tubers as well as rhizoidal propagula that orginate from costal cells. A detailed treatment of the species along with an account of its world distribution was given by Arts & Sollman (1991).