Pseudotaxiphyllum distichaceum (Mitt.) Z.Iwats.

Authority

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

Family

Plagiotheciaceae

Scientific Name

Pseudotaxiphyllum distichaceum (Mitt.) Z.Iwats.

Description

Species Description - Plants slender, in lustrous, soft, yellow-green, thin, flat mats. Stems creeping, to ca. 2.5 cm long, but often only ca. 1 cm, scarcely and irregularly branched, complanate-foliate; in crosssection with 1-2 rows of small thick-walled cells surrounding larger thinner-walled cells, central strand none but cells smaller toward center or central strand poorly differentiated; pseudoparaphyllia none; axillary hairs with a single short-rectangular light-brown basal cell and 2 elongate hyaline distal cells. Stem and branch leaves similar, distant and scarcely overlapping except toward stem and branch apices, complanate, wide-spreading to squarrose, curved and asymmetric, little altered when moist, oblong-lanceolate, (1-)1.4-1.7(-2) mm long, acute to short-acuminate, usually abruptly so, sometimes undulate, not decurrent but slightly rounded to the insertion; margins serrulate above, subentire to distantly serrulate below, plane or narrowly recurved below; costa short and double, usually with one fork longer than the other, rarely absent; cells linear-subflexuose, smooth or slightly prorulose in upper part of leaf, thin- to firm-walled, not porose, somewhat shorter in the acumen, becoming rectangular and somewhat porose toward the insertion; alar cells not or scarcely differentiated. Asexual propagula common, clustered in leaf axils at stem and branch apices, slender, ca. 0.35 mm long when mature, ca. 4-stratose, with 1-5 leaf primordia at apex. [Inflorescences and sporophytes unknown from the New World; description based on material from India.] Dioicous ? (no perigonia seen), but reported as autoicous. Perichaetial leaves erect, oblong-lanceolate, ca. 1.4 mm long, abruptly long-loriform; margins serrulate (often bluntly so) in the acumen, subentire below, plane; costa none; cells broadly linear, smooth, thin- to thick-walled, becoming narrower in the acumen and shorter toward the insertion; alar cells not differentiated. Setae elongate, smooth, reddish, ca. 1.5 cm long, curved just below the urn; capsules horizontal, symmetric, broadly cylindric with a distinct neck, ca. 1.1-1.5 mm long; exothecial cells quadrate to short-rectangular, ± thin-walled, not collenchymatous, becoming smaller in ca. 5 rows at the mouth; annulus of 1-3 rows of small thin-walled cells, deciduous; operculum conic; exostome teeth shouldered, bordered, on the front surface finely cross-striolate below, with overlying papillae at midtooth, papillose above, trabeculate at back; endostome papillose throughout, with a medium-high basal membrane, segments keeled, not or narrowly perforate, ca. as long as the teeth, cilia in pairs, nodulose. Spores spherical, smooth, ca. 11 µm diam. Calyptrae cucullate, naked, smooth.

Discussion

1. Pseudotaxiphyllum distichaceum (Mitt.) Z. Iwats., J. Hattori Bot. Lab. 63: 449. 1987; Stereodon distichaceus Mitt., J. Proc. Linn. Soc., Bot. Suppl. 1: 105. 1859; Isopterygium distichaceum (Mitt.) A. Jaeger, Ber. That-igk. St. Gallischen Naturwiss. Ges. 1876-77: 439. 1878. Plate 127, figures 1-6 Discussion. Pseudotaxiphyllum distichaceum has asymmetric leaves that are sharply serrulate above. The most distinctive features are the clusters of elongate propagula, with leaf primordia only at their apices, in leaf axils at the ends of stems and branches. The species seems most closely related to the widespread P elegans (Brid.) Z. Iwats., which has not been reported from the American tropics. That species has ± symmetric leaves, propagula distributed all along the stems and branches, and leaf primordia not restricted to the apices of the propagula.

Distribution

Range. Eastern North America, Mexico, Honduras, Costa Rica, Colombia, eastern Asia; Hispaniola (Dominican Republic); known from a single collection (Zanoni et al. 42050, JBSD, NY), growing on rock, at ca. 3100 m.

Mexico North America| North America| Honduras Central America| Costa Rica South America| Colombia South America| China Asia| Japan Asia| Taiwan Asia| South Korea Asia| North Korea Asia| Mongolia Asia| Dominican Republic South America|