Isopterygium jamaicense (E.B.Bartram) W.R.Buck
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Authority
Buck, William R. 1998. Pleurocarpous mosses of the West Indies. Mem. New York Bot. Gard. 82: 1-400.
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Family
Hypnaceae
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Scientific Name
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Description
Species Description - Plants small, in lustrous, soft, pale- to yellow-green, often small, dense mats. Stems creeping, to ca. 2 cm long, irregularly and freely branched, the branches simple, complanate-foliate; in cross-section with 1-2(-3) rows of small firm-walled cells surrounding a few large thin-walled cells, central strand absent; pseudoparaphyllia filamentous; axillary hairs with a single relatively long brown basal cell and 2(-3) elongate hyaline distal cells. Stem and branch leaves similar, ± crowded, wide-spreading, complanate, symmetric, ovate-lanceolate, 0.9-1.1 mm long, gradually acuminate, ± concave; margins entire or rarely subserrulate, plane or narrowly incurved below; costa short and double or absent; cells linear, straight, smooth, thin-walled, not porose, the apical few cells somewhat shorter, becoming shorter, broader and laxer in 1-2 rows across the insertion; alar cells relatively well differentiated in basal angles, sometimes reaching the costa, in 35 rows, extending up the margins by 4-7 cells, quadrate to short-rectangular. Asexual propagula not seen. Autoicous. Perichaetial leaves erect, narrowly triangular, 0.5-0.8 mm long, gradually acuminate; margins subentire, plane to erect; costa none; cells linear, smooth, thin- to firm-walled, not porose, becoming shorter, broader and thinner-walled toward the insertion; alar cells not differentiated. Setae elongate, smooth, orange, becoming reddish with age, 0.5-0.7 cm long, straight; capsules erect, symmetric, cylindric, 0.8-1.2 mm long, constricted slightly below the mouth when immature, not at all when mature; exothecial cells thin-walled, the crosswalls thinner than the vertical walls, obscurely collenchymatous above, not at all below; annulus not differentiated; operculum obliquely short conic-rostrate; exostome teeth shouldered, bordered, on the front surface cross-striolate below, partially from horizontally arranged papillae, coarsely papillose above, trabeculate at back only in upper portions; endostome with a low, smooth basal membrane (of 2-3 rows of cells), segments smooth or obscurely papillose, linear, keeled, not perforate, ca. as long as the teeth but often broken and appearing shorter, cilia none. Spores spherical, finely papillose, 12.5-17 µm diam. Calyptrae cucullate, naked, smooth.
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Discussion
2. Isopterygium jamaicense (E. B. Bartram) W. R. Buck, Brittonia 36: 88. 1984; Platygyriella jamaicensis E. B. Bartram, J. Wash. Acad. Sci. 26: 14. 1936. Plate 124, figures 1-7 Discussion. Isopterygium jamaicense is very closely related to I. tenerum and sterile material can only be separated imperfectly. The distinguishing features are the erect capsule not at all constricted below the mouth when mature, the low basal membrane giving rise to linear, nonperforate segments, and no cilia. The leaves are somewhat larger than those in I. tenerum and there are often more alar cells. However, considering the variability of I. tenerum, one has little faith in such characters. Isopterygium jamaicense always occurs on bamboo culms. Specimens of I. tenerum that grow on bamboo have endostomial segments often narrower (but not linear), but the basal membrane remains fairly high and cilia are present. Isopterygium jamaicense is probably more common than the collections indicate, however, collectors may overlook it in an attempt to avoid the weedy I. tenerum.
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Distribution
Range. Mexico, Guatemala; Jamaica; seemingly confined to bamboo culms (at the nodes), in moist forests, at sea level to 350 m.
Mexico North America| Guatemala Central America| Jamaica South America|