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Platygyriella densa W. R. Buck 1984

Comprehensive Description

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Platygyriella densa

Platygyriella densa (Hook. in Kunth) W. R. Buck, Brittonia 36: 86. 1984a; Leskea densa Hook. in Kunth, Syn. Pl. 1: 61. 1822; Entodon densus (Hook. in Kunth) Mitt., J. Linn. Soc., Bot. 12: 531. 1869; Erythrodontium densum (Hook. in Kunth) Paris, Index Bryol. ed. 2, 2: 158. 1904; Bryosedgwickia densa (Hook. in Kunth) Bizot & P. de la Varde, Rev. Bryol. Lichénol. 20: 246. 1951. Type: Mexico. [Michoacán:] Between Pazcuaro and Ario, 1828–2111 m, Humboldt & Bonpland s.n. (holotype: BM!; isotype: NY!).

Platygyrium guatemaliense Schimp. ex A. Jaeger, Ber. Thätigk. St. Gallischen Naturwiss. Ges. 1876–77: 276. 1878, nom. nud.

Entodon pallidissimus Müll. Hal., Linnaea 42: 494. 1879; Erythodontium pallidissimus (Müll. Hal.) Paris, Index Bryol. 437. 1896; Bryosedgwickia pallidissima (Müll. Hal.) Bizot & P. de la Varde, Rev. Bryol. Lichénol. 21: 10. 1952. Type: Venezuela. Prope Coloniam Tovar, 1854–5, A. Fendler 96 (lectotype: NY!, designated by Buck, 1984a).

Platygyriella helicodontioides Cardot, Rev. Bryol. 37: 9. 1910. Type: Mexico. México: Amecameca, 1908, Pringle 15256 (lectotype: PC!; isolectotypes: NY!, US!, both types designated by Buck, 1984a).

Erythrodontium subdensum Broth. & Thér. in Thér., Recueil Publ. Soc. Havraise Études Diverses 88: 313. 1921; Bryosedgwickia subdensa (Broth. & Thér.) Bizot & P. de la Varde, Rev. Bryol. Lichénol. 21: 10. 1952. Type: Costa Rica. Alajuela, 900 m, Jan 1910, O. Jiménez s.n. (holotype: H!; isotype: PC!).

Plants small and slender, in mats, dull green to golden. Stems to ˜4 cm long, mostly shorter, irregularly branched, the branches prostrate, short; stems in cross section with 2–4 rows of small, thick-walled cells surrounding abruptly larger, thinner walled cells, central strand lacking; pseudoparaphyllia filamentous; axillary hairs with 1(–2) short, brown basal cell(s) and 3–5 elongate, hyaline apical cells. Asexual reproduction sometimes by flagellate branches. Leaves 0.35–0.8 mm long, erect-spreading wet or dry, lanceolate to lanceolate-ovate, concave, gradually acuminate; margins entire or more often minutely serrulate almost throughout, plane or sometimes reflexed; costa short and double; cells linear, rarely shorter at the apex; alar cells quadrate to oblate, usually extending to the costa, the decurrencies usually of 1–2 greatly enlarged cells. Dioicous. Setae 1.2–1.5 cm long; capsules ˜2 mm long; operculum short- to high-conic; exostome teeth orange, striolate to papillose below, smooth or faintly papillose above; endostome with a moderately high basal membrane, with walls sometimes very thickened, often coarsely papillose, and narrow, flat, finely to coarsely papillose segments, cilia none. Spores 13–20 μm in diameter.

Distribution and ecology: Mexico (where it is common and weedy), Costa Rica, Venezuela, Bolivia, Brazil, Paraguay, and Peru; mistakenly reported from Haiti (Buck and Steere, 1983); commonly on bark of deciduous tree trunks, sometimes on rocks, in mesic to dry forests, at (200–)400–1700(–2400) m.

Illustrations in publications: Fig. 161F–H in Bartram (1949: 363); Pl. 757 in Buck (1994: 1020).

Discussion: This moss is often found in mixtures with other mosses, often on tree trunks. When by itself, it is frequently small, sterile, and weatherworn. It is distinctive by its small size, ovate-lanceolate, gradually acuminate leaves, short-double costa, and one or two greatly enlarged cells of the decurrencies (that typically remain attached to the stems upon dissection). The moderately high basal membrane of the endostome, which is coarsely papillose and often has strikingly thick walls, and narrow, flat segments are unmistakable. There is little chance of confusion with P. pringlei, which has much larger, imbricate, and more or less abruptly tapered leaves and usually more than two enlarged cells in the decurrencies, as well as a rupestral habit.

Specimens examined: MEXICO. Chiapas: Mpio. Angel Albino Corzo, 9 km S of Finca Liquidambar, 15°42'N, 92°45'W, 2000–2150 m, Delgadillo 4707 (MEXU, NY). Districto Federal: La Venta, San Miguel, 3469–3965 m, 17 Oct 1926, Antipovich s.n. (MO, NY). Guerrero: Mpio. Chilpancingo de los Bravos, Ixtamalco, 18 km W of Chilpancingo on road to Olmitemi, 1500 m, Thomas & Contreras 3728 (NY). Jalisco: Etzaltan, Pringle, Plantae Mexicanae 10617 (US); Río Blanco, Guadalajara, Pringle 15235 (US); N slope of La Cumbre, 16 km SW of Autlán on La Resolana road, 1464 km, Crum 481 (MICH, NY). México: Barranca de Malinaltenango, 18°46'N, 99°42'W, 1450–1600 m, Buck 18174 (NY); Santa Fé, Pringle 15653 (US); Canada, Pringle 15113 (US). Michoacán: Vicinity of Morelia, Cerro Azul, 2300 m, Arsène 4534, 4546, 4551, 4795, 4796 (US); Jesús del Monte, 2000 m, Arsène 7614 (US); Campanario, 2200 m, Arsène 7450, 7525 (US); on Federal Hwy. 15, 41 km W of Cd. Hidalgo, Sharp et al. 2191 (NY, TENN). Morelos: At Mirador, near Km 67 on Cuernavaca–Mexico City toll road, Hwy. 95D, 1952 km, Magill 2510 (NY, TENN). Nayarit: Mpio. Acaponeta, La Ciénaga, ˜16 km NW of Mesa del Nayar, 2593 km, Norris & Taranto 14421a (NY, TENN). Oaxaca: Dist. Putla, ˜19 km S of Putla de Guerrero on road to Pinotepa Nacional, Norris & Taranto 15876 (NY, TENN). Puebla: Vicinity of Puebla, Hacienda Santa Bárbara, 2160 m, Arsène 4516 (US). Durango, el Oro, Rangel & Arsène 4881 (US). Sinaloa: Along Hwy. 40, ˜10 km W of Las Palmitas, 2288 m, Norris 20448 (NY, TENN). GUATEMALA. Baja Verapaz: Near Patal, 1585 m, Sharp 2906 (US); Chimaltenango: Along Río Guacalate, SE of Chimaltenango, ˜1700 m, Standley 80038 (NY); Quezaltenango: Region of Las Nubes, S of San Martín, Chile Verde, ˜2250 m, Standley 83644 (NY); Suchitepéquez: S slope of Volcán Santa Clara, 1219 m, July 1948, Holdridge s.n. (NY). HONDURAS. Lempira: Montana de Celaque, along Río Arquegual, 7.5 km SW of Gracias, 14° 34'N, 88°39'W, 1400 m, Allen 11160 (MO, NY). EL SALVADOR. La Liberted: Cafetale de Miguel Eduardo Araujo, 13°39'N, 89°22'W, 1000 m, Monro et al. 2320 (MO); Santa Ana: Cerro Verde National Park, 13°29'N, 88°32'W, 2365 m, Sidwell et al. 455 (MO). NICARAGUA. Jinotega: ˜3.2 km NW of Jinotega, road to San Rafael del Norte, 1000 m, Croat 43029 (MO); Madriz: Cerro Quisuca, 13°31'N, 86°31'W, 1100–1250 m, Stevens 16139 (MO); Managua: Sierra de Managua, 600–900 m, Garnier 707 (US). COSTA RICA. Alajuela: Carrillos de Poas, cerca de Río Poas, Brenes 17401 (NY); San José: Santa María de Dota, 1600 m, Standley 43172 (NY). PANAMA. Chiriquí: Cerro Colorado, Chami Camp, 8°35'N, 81°44'W, 1050 m, Allen 5006A (MO); Coclé: El Valle, Tyson 2477 (MO); Los Santos: Trail between Jobero and headwaters of Río Pedregal, 500–780 m, Croat 34535 (MO). BOLIVIA. Tajira: Prov. Arce, slope of Cerro Nogal, 0.5 km N of Quebrada Nogal, 2–5 km NW of Communidad La Mamora, 22°09'S, 64°41'W, 1230 m, Lewis 84-2157 (F, NY). BRAZIL. Goiás: Alto Paraíso, Chapada dos Veadeiros, am Rio São Miguel westlich des Nationalparks, 800 m, Schäfer-Verwimp 9857 (NY). PARAGUAY. Cordillera: Cerro Ybitú Silla, 1 km S of Tobatí, 25°12'S, 57°07'W, 297 m, Zardini 6024 (MO, NY). PERU. Above San Miguel, 1830 m, Foote 25 (NY).
bibliographic citation
Ireland, Robert Root and Buck, William R. 2009. "Some Latin American Genera of Hypnaceae (Musci)." Smithsonian Contributions to Botany. 1-97. https://doi.org/10.5479/si.0081024X.93