1. Entodon Müller Hal., Linnaea. 18: 704. 1845. • [Greek entos, inside, and odon, tooth, alluding to peristome teeth inserted below capsule mouth].
Plants medium-sized to moderately large, in extensive mats, lustrous. Stems creeping (spreading to ascending in E. concinnus), irregularly branched to subpinnate, branches relatively short, terete- or complanate-foliate. Leaves oblong-lanceolate to oblong-ovate, not plicate (slightly plicate in E. brevisetus); base not decurrent; alar cells quadrate to subquadrate; laminal cells straight to ± flexuose; basal cells shorter, walls usually porose. Seta single. Capsule yellow- to red-brown; columella exserted; operculum long-conic to obliquely rostrate; prostome absent; exostome teeth yellow-brown to reddish; endostome basal membrane low, segments linear, as long as or shorter than exostome teeth, rarely rudimentary.
Species ca. 70 (10 in the flora): North America, Mexico, West Indies, Central America, South America, Eurasia, Africa, Atlantic Islands, Pacific Islands, Australia.
Plants of Entodon are characterized as flattened or terete pleurocarpous mosses with concave leaves and a weak double costa. The alar cells are quadrate and numerous. The two subgenera, Entodon and Erythropus Mizutani, are separated on sporophytic characters, specifically the color of the seta, the presence or absence of an annulus, and the color and ornamentation of the exostome teeth. The genus is well represented in Andean South America and East Asia. Species are often best identified using exostomial ornamentation, but sterile plants can be identified from leaf characters.