Orthostichopsis tetragona (Sw. ex Hedw.) Broth.
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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
Pterobryaceae
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Scientific Name
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Description
Species Description - Plants relatively robust, the secondary stems pendent to ca. 60 cm long, but mostly <10 cm long, in yellow-green to brownish wefts. Primary stems short, creeping, filiform, with small, reduced ecostate leaves, turning ca. 90° and becoming the upright secondary stem (stipe), the creeping stem continuing by a bud from near the base of the stipe, secondary stems initially erect but soon becoming pendent, irregularly pinnate, not complanate-foliate; in cross-section with 4-6 rows of small thick-walled colored cells surrounding larger thinner-walled cells, central strand none; paraphyllia none; pseudoparaphyllia filamentous, numerous, but relatively distant from branch primordia and difficult to find on expanded branches; axillary hairs with 2 short brown basal cells and 2 elongate hyaline distal cells. Secondary stem leaves not particularly spirally arranged, loosely erect, oblong-ovate, 2-2.6(-3.5) mm long, abruptly aristate (the arista ultimately 1-2-seriate, often crispate, 1/4-1/3 the leaf length), ± concave, long-decurrent but dissection usually leaving decurrencies on the stems; margins serrulate from base of arista almost to base, incurved almost throughout below arista; costa single, ending 2/3-3/4 the length of the leaf base; cells linear to linear-flexuose, smooth, firm- to thick-walled, porose; alar cells mostly oblate in extensive areas, rectangular in the decurrencies, extending up the margins by 20-35 cells, not reaching the costa, yellowed at costa base, adjacent nonalar areas, the decurrencies, and sometimes at base of alar region. Branch leaves conspicuously 5-seriately arranged, erect, oblong-lanceolate to oblong-ovate, 1.6-2.2 mm long, abruptly cuspidate (rarely aristate), the cusp ca. 0.15 mm long and often broken, concave, plicate, decurrent; margins serrulate above or almost to base, incurved at base of acumen or almost throughout; costa single, ending ca. 3/4 the leaf length, or absent on occasional leaves; cells linear to linear-flexuose, shorter in the cusp, smooth, thick-walled, porose; alar cells ± abruptly differentiated, mostly oblate, those of the decurrencies rectangular, extending up the margins by (15-)20-30 cells, not reaching the costa, yellowed across the insertion and into the decurrencies. Asexual propagula none. Dioicous. [Sporophytes not seen from the West Indies; description based on Trinidadian material.] Perichaetia large, conspicuous; leaves convolute, lanceolate, to 4.2 mm long, gradually acuminate, concave; margins subentire, plane to incurved; costa single, ending ca. 3/4 the leaf length; cells linear-flexuose, smooth, very thick-walled, the walls as wide as or wider than the lumina, porose, becoming yellow toward the insertion but otherwise only slightly differentiated. Setae very short, smooth, ca. 0.6 mm long; capsules immersed, erect and symmetric, cylindric to broadly cylindric, 1.5-2.21-3) mm long; exothecial cells short-rectangular, thin- to firm-walled, becoming oblate at the mouth; annulus not differentiated; operculum conic-rostrate, ca. 0.75 mm long; peristome inserted below the mouth, exostome teeth yellow, on the front surface appearing broadly furrowed, smooth, with a well-developed prostome; endostome rudimentary (or absent?). Spores ovoid to oblong, faintly roughened, 34-60 µmlong. Calyptrae cucullate, crispate-pilose.
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Discussion
1. Orthostichopsis tetragona (Hedw.) Broth, in Engl. & Prantl, Nat. Pflanzenfam. 1(3): 805. 1906; Hypnum tetragonum Sw. ex Hedw., Sp. Muse. Frond. 246. 1801; Isothecium tetragomun (Hedw.) Brid., Bryol. Univ. 2: 377. 1827; Neckera tetragona (Hedw.) Midl. Hal., Syn. Musc. Frond. 2: 125. 1850; Meteorium tetragomun (Hedw.) Mitt., J. Linn. Soc., Bot. 12: 431. 1869; Pilotrichella tetragona (Hedw.) Besch., Mém. Soc. Sci. Nat. Cherbourg 16: 222. 1872; Hildebrandtiella tetragona (Hedw.) Paris, Index Bryol. Suppl. 182. 1900. Plate 58, figures 1-6 Pterigymmdrum aureum Brid. ex P. Beauv., Prodr. Aethéogam. 86. 1805; Pterigynandrum quadrifarium Brid., Bryol. Univ. 2: 194. 1827, nom. illeg., fide Britton (1913: 673). Neckera quinquefaria Midl. Hal., Syn. Muse. Frond. 2: 124. 1850; Meteorium quinquefarium (Midl. Hal.) Mitt., J. Linn. Soc., Bot. 12: 431. 1869; Pilotrichella quinquefaria (Midl. Hal.) A. Jaeger, Ber. Thätigk. St. Gallischen Naturwiss. Ges. 1875-76: 255. 1877. Discussion. Orthostichopsis tetragona is characterized by strongly ranked branch leaves that are cuspidate and somewhat plicate; the secondary stem leaves are hairpointed. The alar region is well defined and the differentiated cells numerous and mostly oblate. In the other two Antillean species, the branch leaves are much more long-pointed and the alar cells are fewer and mostly subquadrate to short-rectangular.
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Distribution
Range. Mexico to Panama, Colombia, Venezuela, Ecuador, Peru, northern Brazil, the Guianas, Trinidad and Tobago; Cuba, Jamaica, Hispaniola (Dominican Republic), St. Eustatius, Martinique, Grenada; mostly growing pendently from tree trunks and branches, rarely falling and becoming terrestrial, in humid forests, at sea level to 600 m.
Mexico North America| Central America| Venezuela South America| Colombia South America| Ecuador South America| Peru South America| Brazil South America| French Guiana South America| Guyana South America| Suriname South America| Trinidad and Tobago South America| Cuba South America| Jamaica South America| Dominican Republic South America| Sint Eustatius South America| Martinique South America| Grenada South America|