Pseudotaxiphyllum

• Authority

  Buck, William R. 1998. Pleurocarpous mosses of the West Indies. Mem. New York Bot. Gard. 82: 1-400.

• Family

  Plagiotheciaceae

• Scientific Name

  Pseudotaxiphyllum

• Description

  Genus Description - Plants small to medium-sized, in often lustrous, mostly soft, bright- to yellow-green, thin to dense mats. Stems creeping, scarcely and irregularly branched, often complanate-foliate; in cross-section without a hyalodermis, with small thick-walled cells surrounding larger thinner-walled cells, central strand usually present; pseudoparaphyllia none; axillary hairs with a single short-rectangular light-brown basal cell and 2(-3) elongate hyaline distal cells. Stem and branch leaves similar, crowded or more characteristically lax, often complanate, mostly wide-spreading, asymmetric, lanceolate to oblong-lanceolate, gradually or abruptly short-acuminate, usually not concave; margins serrulate above, mostly sharply so, subentire to serrulate below, plane to narrowly recurved below; costa short and double or absent; cells linear, often flexuose, smooth or rarely inconspicuously prorulose in leaf apex, thin- to firm-walled, not porose, not or slightly shorter in the acumen, becoming shorter, ± rectangular and sometimes porose toward the insertion; alar cells not or scarcely differentiated. Asexual propagula common, clustered in leaf axils, mostly elongate, with leaf primordia. Mostly dioicous. Perichaetial leaves erect, oblong-lanceolate, abruptly long-acuminate; margins serrulate above, entire below, plane; costa usually none; cells linear, smooth, thin- to thick-walled, becoming shorter and broader toward the insertion; alar cells not differentiated. Setae elongate, smooth, reddish, straight or curved just below the urn; capsules suberect to horizontal, straight to arcuate, symmetric to asymmetric, short-cylindric; exothecial cells quadrate to rectangular, often thin-walled, not collenchymatous; annulus differentiated; operculum conic; peristome double, exostome teeth shouldered, bordered, on the front surface cross-striolate below, papillose above, trabeculate at back; endostome with a medium-high to high basal membrane, segments keeled, not or narrowly perforate, shorter than or ca. as long as the teeth, cilia present. Spores spherical, smooth to finely papillose. Calyptrae cucullate, naked, smooth.

• Discussion

  Pseudotaxiphyllum Z. Iwats., J. Hattori Bot. Lab. 63: 448. 1987; Isopterygium subgen. Pseudotaxiphyllum Z. Iwats., J. Hattori Bot. Lab. 33: 334. 1970, nom. nud.; Isopterygium sect. Pseudotaxiphyllum Z. Iwats., J. Hattori Bot. Lab. 63: 445. 1987, nom. nud. in syn. Discussion. Pseudotaxiphyllum was erected by Iwatsuki (1987) as a genus for accommodating a group of seven species, mostly Asian, that differ from Isopterygium by the lack of pseudoparaphyllia, gemmiform propagula, dioicous sexuality, and presence of a capsular annulus. Admittedly, these are technical differences, tedious to observe. However, the plants do have a different appearance and are often more lustrous than those of Isopterygium.