Prionodon densus (Sw. ex Hedw.) Müll.Hal.

Authority

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

Family

Prionodontaceae

Scientific Name

Prionodon densus (Sw. ex Hedw.) Müll.Hal.

Description

Species Description - Plants relatively robust, the secondary stems to ca. 15 cm long, but often 5-6 cm, in mostly ± stiff, bright- to golden-green, dense, epiphytic colonies. Primary stems creeping, turning ca. 90° and becoming the secondary stem, the creeping stem continuing by a bud from near the base of the secondary stem, secondary stems mostly horizontal to pendent, simple to irregularly or regularly pinnate and then ± frondose, ± stipitate but without differentiation of stipe leaves and thus not truly stipitate; in cross-section with 6-8 rows of small thick-walled cells surrounding larger firm-walled cells, central strand of small firm-walled cells; paraphyllia none; pseudoparaphyllia broadly foliose; axillary hairs short, with 1-2(-3) short (quadrate to oblate) brown basal cells and (1-)2-3(-5) short-rectangular hyaline distal cells. Primary stem leaves often eroded or buried in tomentum, erect to erect-spreading, oblong-triangular, 1-1.7 mm long, ± gradually slenderly long-acuminate, the acumen as long as or longer than the leaf base, ± plicate, short-decurrent; margins ± entire throughout or with a few small teeth in the acumen, often recurved below; costa single, ending near the base of the acumen; cells fusiform, ca. 6-8:1, unipapillose on both surfaces, thick-walled, the walls almost as wide as to wider than the lumina, porose; alar cells subquadrate to oblate, thick-walled and ± cruciform, mostly smooth but a few cells unipapillose, extending up the margins by 10-20 cells, in 58 rows. Secondary stem and branch leaves similar but those of branches often smaller, erect to spreading, often ± crispate when dry, lanceolate, ca. 4-6 mm long, gradually acuminate, frequently fragile with broken apices, ± plicate at base, decurrent; margins typically toothed in upper 1/2-5/6 with uni- to multicellular teeth, rarely subentire, mostly plane, sometimes narrowly recurved below; costa single, subpercurrent, often ± flexuose above, in section with dorsal stereids; cells ± isodiametric to short-rectangular, 1-2(-4):1, unipapillose on both surfaces, irregularly thick-walled, porose, distinctly to not differentiated as a border, when differentiated ca. 3-4:1, smooth, becoming long-rectangular and smooth juxtacostally toward the insertion; alar cells ± isodiametric, the lumina often oblate-cruciform, smooth, thick-walled, in large distinct areas extending somewhat to well up the margins, in 12-18 rows. Asexual propagula, other than fragile leaves, not seen. Dioicous. Perichaetia usually on underside of stems and thus often overlooked; leaves strongly differentiated, smaller than vegetative leaves and immersed among them, the innermost smaller than the outermost, broadly oblong-ovate, 1.2-1.6 mm long, ± obtuse, long-cuspidate to awned; margins crenulate-serrulate above, entire below, awn with a few blunt teeth, plane; costa single, ending in lower part of cusp or awn; cells fusiform to long-rectangular, 4-8:1, smooth, thick-walled, porose, shorter in a narrow band across the apex, becoming broader and often thinner-walled across the insertion; alar cells not differentiated or quadrate in 2-4 rows. Setae short, smooth, reddish, ca. 1-1.5 mm long; capsules emergent to short-exserted from vegetative leaves, erect and symmetric, ± globular to ovoid to broadly oblong-cylindric, rounded at base, indented at point of attachment to seta, 1-1.5(-2): 1; exothecial cells rounded-oblate to short-rectangular, firm-walled, becoming shorter and oblate in 2-5 rows at the mouth; annulus bryoid, of a double row of thick-walled, ± bulbous cells, revoluble in fragments; operculum obliquely rostrate from a broad-conic base, ca. 1-1.25 mm long; exostome teeth pale, sometimes poorly formed, coarsely papillose throughout, not trabeculate at back; endostome with a low, ± smooth basal membrane, segments coarsely papillose, united above in groups of 2 or more, often ± reticulate, the connections between segments from halfway up to the apices, not keeled, mostly not perforate, often coarsely appendiculate, mostly longer than the teeth, cilia none. Spores spherical, papillose, 12-18 µm diam. Calyptrae large, seemingly campanulate when immature, but at maturity splitting up one side and thus cucullate, naked, roughened above.

Discussion

1. Prionodon densus (Hedw.) Müll. Hal., Bot. Zeitung (Berlin) 2: 130. 1844; Hypnum densum Hedw., Sp. Musc. Frond. 282. 1801; Neckera densa (Hedw.) Wilson, London J. Bot. 6: 292. 1847; Pilotrichum densum (Hedw.) Müll. Hal., Syn. Muse. Frond. 2: 160. 1850. Plate 70, figures 1-13 Neckera luteovirens Taylor, London J. Bot. 5: 59. 1846; Pilotrichum luteovirens (Taylor) Müll. Hal., Syn. Musc. Frond. 2: 161. 1850; Prionodon luteovirens (Taylor) Mitt., J. Linn. Soc., Bot. 12: 417. 1869; Prionodon densus var. luteovirens (Taylor) E. B. Bartram, Fieldiana, Bot. 25: 247. 1949. Prionodon dichotomus Hampe, Linnaea 32: 150. 1863. Prionodon patentissimus Besch., Bull. Herb. Boissier 2: 394. 1894. Prionodon haitensis Renauld & Cardot, Bull. Soc. Roy. Bot. Belgique 33(2): 125. 1895, non Müll. Hal., Hedwigia 37: 239. 1898, hom, illeg. Prionodon haitensis Müll. Hal., Hedwigia 37: 239. 1898, hom, illeg., non Renauld & Cardot, Bull. Soc. Roy. Bot. Belgique 33(2): 125. 1895; Prionodon piradae Paris, Index Bryol. Suppl. 285. 1900. Discussion. Prionodon densus has lanceolate, mostly sharply toothed leaves with short, incrassate, unipapillose laminal cells, and numerous alar cells with cruciform lumina. The capsules vary from almost globular to shortly cylindric, and are usually shortly exserted from the vegetative leaves. The extreme variability of the species has resulted in a wealth of synonyms. The plants may be simple to densely pinnate, leaves erect to wide-spreading, margins almost entire to multicellularly toothed, border cells differentiated or not, alar cells restricted to the lower one-fifth of the leaf or less or extending almost to midleaf, capsules globular to cylindric. However, to date, no correlation of these various character state variations has been found to justify segregation as species. See Griffin (1974) for illustrations of some of the variation within P. densus.

Distribution

Range. Mexico to Panama, Colombia and Venezuela to Bolivia, southeastern Brazil, eastern Africa; Cuba, Jamaica, Hispaniola (Haiti and Dominican Republic); growing on tree trunks, less often rocks, in humid broadleaf forests, at 1000-2000 m.

Mexico North America| Central America| Colombia South America| Venezuela South America| Ecuador South America| Peru South America| Bolivia South America| Brazil South America| Djibouti Africa| Eritrea Africa| Ethiopia Africa| Somalia Africa| Egypt Africa| Sudan Africa| South Sudan Africa| Madagascar Africa| Mauritius Africa| Seychelles Africa| Uganda Africa| Rwanda Africa| Burundi Africa| Kenya Africa| Tanzania Africa| Mozambique Africa| Malawi Africa| Zambia Africa| Zimbabwe Africa|