Monographs Details: Erythrodontium
Authority: Sharp, Aaron J., et al. 1994. The Moss Flora of Mexico. Part Two: Orthotrichales to Polytrichales. Mem. New York Bot. Gard. 69 (2)
Description:Genus Description - Plants rather small to medium-sized, in green, golden, or red-brown, loose, shiny mats. Stems creeping, ± straight, irregularly pinnate with relatively short, often ascending, julaceous branches, in section showing 1-4 layers of small, thick-walled cells surrounding ± thin-walled, large cells and a central strand of a few, very thin-walled, sometimes nodose cells with wavy outlines; pseudoparaphyllia foliose. Stem and branch leaves slightly differentiated, the stem leaves larger, usually broadly ovate and gradually acuminate; branch leaves imbricate, usually short to long oblong-ovate, abmptly rounded to an apiculus, slightly concave to distinctly cucullate at apex, broadly decurrent; margins mostly plane, rarely recurved, entire or more often sermlate at the apex; costa short and double to absent, the costal cells usually porose; median cells linear-rhomboidal, straight to subflexuose, ± thin-walled, the apical cells shorter, thick-walled (the walls sometimes thicker than the lumina), flexuose; alar cells subquadrate (wider than long) in large triangular groups extending up the margin 1/4 to 1/2 the leaf length, usually not reaching the costa, sometimes the alar cells nearer the costa with distinctly thick and porose walls; cells between costa and alar region porose; cells of the decurrencies in many rows, of the same size and shape as the alar cells. Autoicous. Perigonia small, scattered along the stem near the perichaetia. Perichaetial leaves usually sheathing the base ofthe seta, long oblong-lanceolate, acuminate, usually abmptly tapered above, entire to sermlate above, ecostate; cells linear, smooth, thin-walled, straight, becoming shorter, thick-walled and flexuose at the apex, those across the insertion larger, lax and rectangular, extending upward 1/4-1/3 the leaf length. Setae ± elongate (but relatively short and stout in most species), only occasionally more than 1 cm long, yellow to red, slightly twisted; capsules erect, symmetric, short-cylindric, yellow-brown to dark red-brown; exothecial cells isodiametric to short-rectangular; columella sometimes exserted; annulus none; operculum long conic-rostrate, straight; peristome deeply inserted below the mouth, double, red to yellow, the exostome teeth lanceolate, gradually tapered, very narrowly bordered, on the front surface with a ± straight median line and relatively broad plates, the plates smooth, indistinctly striolate, distinctly striolate, or papillose below, usually ± smooth at the apex, on the back surface with broad, smooth, strongly perforate plates; endostome rudimentary, the basal membrane none (or very low?), the segments linear, flat, smooth, not perforate, almost as long as the teeth, or more commonly discontinuous and apparently adhering as small plates to the back ofthe teeth, cilia none. Spores finely to coarsely and densely papillose. Calyptrae naked or hairy.
Discussion:Erythrodontium is characterized by a julaceous habit, relatively broad leaves, numerous differentiated alar cells, mostly wider than long, erect capsules, and rudimentary endostomes. Additionally the genus m a y be separated from Entodon by its decurrent leaves. It is a genus of about 17 species, mainly in South America and Africa. The single Asiatic species, E. julaceum (Schwaegr.) Par., is very closely related to our E. squarrosum. Platygyriella, including in synonymy Bryosedgwickia (Hypnaceae), is segregated from Erythrodontium on the basis of enlarged decurrent leaf cells and a hypnoid peristome.