Porotrichum korthalsianum (Dozy & Molk.) Mitt.
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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
Neckeraceae
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Scientific Name
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Description
Species Description - Plants medium-sized to robust, to ca. 9 cm tall, stipitate-frondose, in dark-green, wiry colonies. Primary stems creeping, slender, secondary stems mostly arising from upturning primary stem, the creeping stem continuing by innovations near the base of the stipe, the secondary stems mostly distinctly stipitate, to ca. 4 cm tall, mostly erect, frondose, irregularly and weakly 2-pinnate, usually complanate-foliate; in cross-section with 3-5 rows of small thick-walled cells, with 5-10 rows in stipe, surrounding large thin-walled cells, in the stipe firm-walled, central strand none or of only 1-3 cells, in the stipe more prominent but small, of a few very thin-walled cells; paraphyllia absent; pseudoparaphyllia broadly foliose with strongly toothed margins; axillary hairs with (1-)2 short brown basal cells and (2-)3(-4) elongate hyaline distal cells. Primary creeping stem leaves reduced, widely spaced, erect-spreading to spreading, ± triangular, 0.3-0.7 mm long, ± abruptly long-acuminate, the acumen almost ½ the leaf length and channelled; margins subentire throughout, mostly incurved above, erect below; costa single, typically extending to base of the acumen or sometimes shorter; cells fusiform, 5-8:1, smooth, firm-walled, ± porose, becoming shorter, rectangular, and distinctly porose across the yellowed insertion; alar cells not differentiated. Stipe leaves lax to imbricate, erect-spreading to spreading, not complanate, triangular-subulate, 1-2.5 mm long, ± abruptly long-acuminate, the apex ± channelled, narrowly decurrent; margins subentire throughout, irregularly incurved to plane above, plane below; costa single, ending near midleaf, not projecting at apex; cells linear-fusiform, 10-15:1, smooth, firm-walled, porose, becoming shorter, thicker-walled and more porose toward the insertion; alar cells scarcely differentiated from other cells at insertion. Secondary stem (continuation of stipe above branching) leaves complanate, spreading, ovate-ligulate, 2-3 mm long, obtuse-apiculate to short-acute, ± concave at base; margins serrate at apex (beyond apex of costa) with 1-3-celled teeth, subserrulate to subentire below, plane or narrowly recurved below; costa single, strong, broad, ending 3/4-9/10 the leaf length, not or scarcely projecting at apex, cells fusiform, 4-8:1, smooth, firm-walled, ± porose, becoming shorter and rhombic, 1-3:1, in large apical area, becoming longer toward the insertion and then at insertion rectangular, thick-walled, strongly porose and yellow; alar cells not or scarcely differentiated. Branch leaves spreading, complanate, ovate-ligulate, 1.4-2 mm long, with details identical to secondary stem leaves. Asexual propagula not seen in the West Indies, but extralimitally flagellate branches rare. Dioicous. [Sporophytes not seen from the West Indies; description based on material from Honduras.] Perichaetial leaves convolute with spreading apices, oblong-lanceolate, 1.1-1.4 mm long, ± gradually acuminate; margins with a couple of very small teeth near the apex but otherwise subentire, incurved to plane; costa none or single and very short; cells fusiform to long-rectangular, ca. 10:1, smooth, thick-walled, porose, becoming broader toward the insertion. Setae elongate, smooth, reddish, 410 mm long; capsules erect, short-cylindric to ovoid, symmetric, 1-2 mm long; exothecial cells subquadrate to short-rectangular, thin- to firm-walled, becoming somewhat smaller at the mouth; annulus of 2-3 rows of oblong thick-walled cells; operculum obliquely rostrate from a conic base, ca. 1.4 mm long; exostome teeth on the front surface cross-striolate in basal 1/10-1/5, densely and ± finely papillose above, slightly trabeculate at back; endostome with a medium-high, sparsely papillose basal membrane, segments densely papillose, keeled, perforate to gaping, as long as the teeth, cilia in groups of 1-2, rudimentary, papillose. Spores spherical, almost smooth to finely roughened, 11-15 µm diam. Calyptrae not seen.
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Discussion
4. Porotrichum korthalsianum (Dozy & Molk.) Mitt., J. Linn. Soc., Bot. 12: 463. 1869; Neckera korthalsiana Dozy & Molk., Pugillus Sp. Nov. Fl. Bryol. Venez. in Prodr. Fl. Bryol. Surinam. [Natuurk. Verh. Holl. Maatsch. Wetensch. Haarlem II, 10(3):] 42. 1854. Plate 49, figures 1-9 Porotrichum cobanense Müll. Hal., Bull. Herb. Boissier 5: 202. 1877; Thamnium cobanense (Müll. Hal.) R. S. Williams, Contr. U.S. Natl. Herb. 16: 24. 1912. Discussion. Porotrichum korthalsianum is most likely to be confused with the much more common P. mutabile. It may be separated by darker-green plants with relatively shorter leaves (about 3:1 rather than 4:1) and leaf apices ± obtuse rather than acute. Admittedly P. mutabile seems closely related, but P. korthalsianum, at least in the West Indies, seems to prefer wet rocks at high elevations, rather than the epiphytic habitats preferred by P. mutabile.
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Distribution
Range, Mexico, Central America, Colombia, Venezuela, Ecuador, French Guiana; Jamaica, Hispaniola (Dominican Republic), Puerto Rico; typically growing on rocks in streams, but also on tree trunks in humid forests, at 1200-2200 m.
Mexico North America| Central America| Colombia South America| Venezuela South America| Ecuador South America| French Guiana South America| Jamaica South America| Dominican Republic South America| Puerto Rico South America|