Monographs Details: Pseudoscleropodium
Authority: Buck, William R. 1998. Pleurocarpous mosses of the West Indies. Mem. New York Bot. Gard. 82: 1-400.
Description:Genus Description - Plants rather robust, in ± lustrous, yellow-green to whitish green, loose mats. Stems mostly creeping with new stems arising from old ones among branches (somewhat similar to Hylocomium splendens), pinnately branched, plumose, the branches well developed, ± tumid, blunt to attenuate, terete-foliate; in cross-section with small thick-walled cells surrounding larger firm-walled cells, central strand small, of small thin-walled cells; paraphyllia none; pseudoparaphyllia foliose; axillary hairs with 1-2 short brown basal cells and several elongate colored distal cells. Stem and branch leaves only slightly differentiated with stem leaves larger and somewhat broader, crowded, ± imbricate, broadly ovate to broadly oblong-ovate, apiculate, very concave, somewhat plicate, especially toward the insertion, scarcely decurrent; margins serrulate above, entire to serrulate below, plane to broadly incurved above, plane to narrowly recurved below; costa single, slender, ending somewhat above midleaf, occasionally forked, occasionally projecting as a small spine at apex; cells linear, ± straight to subflexuose, smooth, somewhat porose throughout, especially in the apex and toward the insertion; alar cells differentiated only in extreme basal angles, quadrate to short-rectangular, not reaching the costa. Asexual propagula none. Dioicous. Perichaetia inconspicuous, common along stems; leaves homomallous, elongate, lanceolate, acuminate, concave; margins serrulate above, entire below, plane; costa short and single or more often none; cells linear, smooth, thick-walled, porose, becoming laxer and thinner-walled toward the insertion; alar cells not differentiated. Setae very long, smooth, reddish, flexuose; capsules strongly inclined, ± arcuate and asymmetric, cylindric; exothecial cells quadrate to short-rectangular, firm- to thick-walled, not collenchymatous, becoming much smaller toward the base of the urn, stomata round-pored; annulus differentiated; operculum high-conic, acute; exostome teeth reddish brown, triangular, strongly shouldered, moderately bordered, on the front surface mostly cross-striolate below, occasionally with overlying papillae, coarsely papillose above, trabeculate at back; endostome mostly smooth, with a high basal membrane, segments keeled, broadly perforate, becoming gaping, ca. as long as the teeth, cilia in groups of 1-3, nodose to appendiculate, shorter than the segments. Spores spherical, finely papillose. Calyptrae not seen.
Discussion:Pseudoscleropodium (Limpr.) M. Fleisch. ex Broth, in Engl., Nat. Pflanzenfam., ed. 2, 11: 394. 1925; Scleropodium sect. Pseudoscleropodium Limpr. in Rabenh., Rabenh. Krypt.-Fl., ed. 2, 4(3 [Laubm. Deutschl.]): 142. 1896.
Discussion. Pseudoscleropodium is distinguished by relatively robust, dioicous plants with tumid branches, usually growing in disturbed habitats. The leaves are very concave, and the alar cells are differentiated only in the extreme basal angles.
Pseudoscleropodium is monospecific (Buck, 1980b: 127), with its sole species widespread. I have not pursued the question of whether or not Pseudoscleropodium is generically distinct from Scleropodium. Although traditionally placed in the Entodontaceae (Brotherus, 1925), Pseudoscleropodium has nothing to do with that family and modem authors agree on its placement in the Brachytheciaceae.