Monographs Details: Trachypus
Authority: Buck, William R. 1998. Pleurocarpous mosses of the West Indies. Mem. New York Bot. Gard. 82: 1-400.
Description:Genus Description - Plants slender to robust, in green to black, mostly ± stiff, often pendent or scrambling, lax colonies. Stems initially creeping, often becoming ascendent to erect distally, little-branched to densely pinnate, the branches mostly short, terete-foliate; in cross-section with small thick-walled cells surrounding larger thinner-walled cells, central strand small (or sometimes absent?); pseudoparaphyllia foliose; axillary hairs with 1-2 short basal cells and a single elongate distal cell, often all cells hyaline. Stem and branch leaves differentiated only in size, appressed to wide-spreading or recurved, sometimes crispate when dry, lanceolate to ovate-lanceolate, mostly gradually short- to long-acuminate, sometimes hairpointed, sometimes plicate, either small-auriculate or not, short-decurrent; margins mostly serrulate and papillose-crenulate throughout, usually plane; costa single, ending near midleaf to well above it, not projecting at apex; cells hexagonal to linear, 2-12:1, seriately pluripapillose over the walls on both surfaces, firm- to thick-walled, mostly not differentiated at margins but becoming smooth at the insertion; alar cells few, quadrate, smooth. Asexual propagula occasionally of flagellate branches. Dioicous. Perichaetial leaves erect, lanceolate, acuminate; margins subentire, plane; costa single, strong; cells linear, smooth or obscurely seriately papillose over the walls, thick-walled, ± porose, becoming shorter and thinner-walled toward the insertion. Setae very elongate, spinose throughout, the spines apparently arising from amplification of projecting cell ends (based on observation of very young sporophytes), from a densely hairy vaginula; capsules long-exserted, erect, symmetric, globose to ovoid; exothecial cells ± isodiametric, firm-walled, not collenchymatous, becoming smaller and finally oblate at mouth; annulus of small firm-walled cells, tardily deciduous; operculum long-rostrate, straight or slightly oblique; peristome inserted slightly below the mouth, pale, exostome teeth on the front surface faintly papillose below, more conspicuously so above, only slightly trabeculate at back; endostome with a high basal membrane, segments rudimentary (not seen adequately), cilia none. Spores spherical, papillose, medium-sized. Calyptrae cucullate, densely erect-hairy.
Discussion:Trachypus Reinw. & Hornsch., Nova Acta Phys.-Med. Acad. Caes. Leop.-Carol. Nat. Cur. 14(2): 708. 1826 ; Papillaria sect. Trachypus (Reinw. & Hornsch.) A. Jaeger, Ber. Thätigk. St. Gallischen Naturwiss. Ges. 1875-76: 273. 1877; Meteorium sect. Trachypus (Reinw. & Hornsch.) Mitt., Trans. Linn. Soc. London, Bot. II, 3: 173. 1891.
Discussion. Trachypus is a distinctive genus of about 5-10 species (depending on level of recognition of the taxa), primarily distributed in southern Asia but ranging into Africa and tropical America. It is characterized by mostly thick-walled laminal cells with seriate papillae over the walls. The setae are very long and spinose. The genus is most likely confused with Cryptopapillaria with similar pluripapillose laminal cells. However, in that genus the cells are shorter and the papillae are not seriate.
Trachypus was monographed by van Zanten (1959), along with other genera traditionally placed in the Trachypodaceae. However, such a familial assemblage is unnatural, with the various genera allied with genera throughout the Meteoriaceae. Thus, the Trachypodaceae have been synonymized with the Meteoriaceae (Buck, 1994a). Only a single species of Trachypus is found in the West Indies.