Plants small, tufted, green or yellowish. Stems short, erect, simple except for a reduced basal antheridial branch. Leaves larger distally, rosulate, crowded, erect-spreading, reduced in size proximally, oblong-ovate to obovate or spathulate, usually acute or acuminate, sometimes apiculate or piliferous, margins plane or erect, entire or serrulate beyond the middle, costa ending well before the apex to percurrent, distal and median cells mostly medium-sized, quadrate to hexagonal to oblong-hexagonal, rarely short-rhomboid, rather lax and thin-walled, sometimes linear at the margins forming a narrow border, proximal cells becoming oblong-rectangular, differentiated alar cells absent. Sexual condition autoicous or polygamous; antheridial branch basal, perigonial paraphyses clavate; perichaetia apparently absent paraphyses. Seta elongate, erect. Capsule exserted, erect or nearly so, narrowly pyriform to short-pyriform, symmetric, often smooth except at the neck when dry, annulus none, exothecial cells transverse, usually linear-oblong, incrassate with radial walls thicker toward the inner tangential wall than the surface wall; stomata present and formed from single cell; peristome absent to well developed, single or double, inserted proximal to the mouth, teeth papillose-striate, weakly trabeculate to appendiculate or absent these features, segments of the endostome, often evanescent and not seen, rarely more than 1/4 the length of the teeth or absent; operculum nearly plane to conic-convex or domed, cells usually in obliquely radial rows. Calyptra large, long-rostrate, cucullate and inflated. Spores smooth or weakly papillose to tuberculate or bacculate-insulate.
Species ca. 20 (12 in the flora): North America, Mexico, Central America, South America, Europe, Asia, Africa, Pacific Islands.
Entosthodon as it is defined here is mainly associated with Mediterranean, shrub-steppe, or desert climates with pronounced wet and dry seasons. The genus is almost certainly under-collected in dry and seasonally dry tropical and warm temperate climates because of the relatively short growth season. Entosthodon is a vexing genus because most species: (1) are short lived; (2) are small and, for the most part, form small, inconspicuous tufts; (3) are usually collected with clinging substrate and careful cleaning is needed; and (4) are frequently in admixture with other small mosses. Fortunately, sporophytes are usually present; otherwise they would probably escape notice. Only E. drummondii is reasonably abundant in herbaria; the other species are represented in collections so uncommonly that their geographic range can only be estimated. It is possible that species are too narrowly drawn in this treatment, but insufficient evidence is available to justify recognizing fewer taxa. Edwin Bartram once remarked (pers. comm.) that he disliked describing new species; he felt defeat when he could not find a proper name but was obliged to provide one or else the taxon would go unrecognized. Entosthodon could have been one of the genera he was talking about.
Entosthodon spathulifolius Cardot & Thériot
This entity from St. Paul Island collected by Trelease was considered by A. J. Grout (1928-1940, vol. 2) to be a Tayloria although he had not seen mature capsules.