Monographs Details: Pilotrichella
Authority: Buck, William R. 1998. Pleurocarpous mosses of the West Indies. Mem. New York Bot. Gard. 82: 1-400.
Description:Genus Description - Plants robust or less often medium-sized, in mostly pendent, ± lustrous, ± stiff, green to golden colonies. Stems mostly pendent, freely branched, the branches often ± turgid, simple; in cross-section with small thick-walled cells surrounding larger ± firm-walled cells, central strand none; paraphyllia absent; pseudoparaphyllia broadly foliose; axillary hairs with (l-)2 short brown basal cells and 2-4 elongate hyaline distal cells. Stem and branch leaves scarcely differentiated, not or scarcely seriately ranked, often ± cuspidate at stem and branch apices, spreading to wide-spreading, oblong-ovate, truncate to long-cuspidate, concave, subauriculate, not decurrent; margins subentire throughout or serrulate above, usually broadly incurved above; costa none or short and double; cells long-hexagonal to linear, smooth, thick-walled, porose; alar cells conspicuously and ± abruptly differentiated in excavate groups, subquadrate, very thick-walled, not porose, colored. Asexual propagula none but leaves rarely caducous although never resulting in naked branches. Dioicous. Perichaetia conspicuous, on branches; leaves differentiated, erect, convolute, oblong-lanceolate, mucronate to cuspidate; margins subentire to serrulate, plane; costa none; cells linear, smooth, thick-walled, porose; alar cells not differentiated. Setae elongate, roughened above, reddish; capsules exserted, erect, symmetric, cylindric; exothecial cells subquadrate, thick-walled, becoming smaller toward the mouth; annulus differentiated in a few rows of small ± thin-walled cells; operculum conic-rostrate, straight; exostome teeth narrowly triangular, ± shouldered, mostly narrowly bordered, on the front surface cross-striolate below, papillose to smooth above, slightly trabeculate at back; endostome with a very low basal membrane, segments slender, usually ± keeled, not or narrowly perforate, much shorter than or almost as long as the teeth, cilia none. Spores spherical, almost smooth to papillose. Calyptrae cucullate, densely erect-hairy, smooth to slightly roughened.
Discussion:Pilotrichella (Miill. Hal.) Besch., Mém. Soc. Sci. Nat. Cherbourg 16: 222. 1872; Neckera sect. Pseudopilotrichum Müll. Hal. subsect. Pilotrichella Müll. Hal., Syn. Muse. Frond. 2: 129. 1850.
Discussion. Pilotrichella is recognized in the restricted sense of only sect. Pilotrichella in Brotherus (1925). It is recognized by relatively robust plants on which the ecostate leaves are oblong-ovate and not or only obscurely ranked. The leaf base is subauriculate and harbors strongly differentiated, colored alar cells in mostly excavate groups. The setae are elongate and roughened above, elevating a capsule with a straight-rostrate operculum. The exostome teeth are cross-striolate below on the front surface. The calyptrae are densely hairy and cucullate.
The majority of species traditionally placed in Pilotrichella are here considered to belong to Orthostichella. They are differentiated by their smaller size, ranked leaves, nonauriculate leaf bases, poorly differentiated alar cells, short setae, obliquely rostrate opercula, papillose exostome teeth, smaller spores, and naked to sparsely hairy calyptrae. Squamidium, our other member of the Lembophyllaceae, has a single costa and mitrate calyptrae.