Macromitrium richardii Schwägr.

  • Authority

    Sharp, Aaron J., et al. 1994. The Moss Flora of Mexico. Part Two: Orthotrichales to Polytrichales. Mem. New York Bot. Gard. 69 (2)

  • Family

    Orthotrichaceae

  • Scientific Name

    Macromitrium richardii Schwägr.

  • Description

    Species Description - Plants slender, yellowish- to olive-green above, redbrown below, in dense, spreading mats. Stems creeping, with numerous erect, sometimes forked branches up to 1 cm high. Leaves strongly crisped and inrolled when dry, spreading with erect-incurved tips when moist, 0.7-1.8 mm long, keeled, lanceolate to ligulate-lanceolate, broadly and sharply acute, obtuse, or obtusely mucronate; margins entire to crenulate due to projecting cells, plane to sometimes slightly reflexed below; costa ending in or 1-3 cells below the apex; upper cells 7-11 µm wide, irregularly hexagonal to rounded-elliptic, firm-walled, bulging, smooth to uni- or pluripapillose in the upper portion, bulging at midleaf; basal cells not numerous, smooth, rectangular to long-linear, with thick, unevenly thickened walls. Gonioautoicous. Perichaetial leaves broadly lanceolate, gradually acuminate; cells usually more elongate and bulging throughout; basal cells with thick, porose walls. Setae 5-13 mm long, smooth; capsules 1-1.6 mm long, ovoid, becoming narrowly ovoid to ovoid-oblong when old and dry, plicate below the mouth to ± 8-plicate the entire length; annulus not seen; exothecial cells not differentiated into bands; stomata at base of urn; peristome single, consisting of 16 rudimentary, delicate, pale, coarsely striate teeth. Spores anisosporous, 22-32 um, densely papillose. Calyptrae lacerate, naked or with a few smooth hairs, covering the entire capsule.

  • Discussion

    Fig. 469

    M. richardii Schwaegr., Sp. Muse Suppl. 2(2): 70. 1826.

    M. didymodon Schwaegr., Sp. Muse Suppl. 2(2): 138. 1827.

    M. goniopodium Mitt., J. Linn. Soc, Bot. 12: 198. 1869.

    M. rhabdocarpum Mitt., J. Linn. Soc, Bot. 12: 199. 1869.

    M. insuhrum Mkl., J. Linn. Soc, Bot. 12:200.1869, non Sull. &Lesq., 1859.

    M. dentatum Schimp. ex Besch., Mem. Soc. Sci. Nat. Cherbourg 16: 190. 1872, nom. nud. in syn.

    M. glaucescensSchimp. ex Besch., Mem. Soc. Sci. Nat. Cherbourg 16: 190. 1872, nom. nud. in syn.

    M. leptophyllumBesch.,Mem. Soc. Sci.Nat.Cherbourg 16:190.1872 (fide Grout, 1946).

    M. domingense Jaeg., Ber. Thatigk. St. Gallischen Naturwiss. Ges. 1872-73: 149. 1874.

    M. tenellum Card., Rev. Bryol. 36: 109. 1909.

    The non-tuberculate basal leaf cells, strongly bulging and usually papillose upper cells, and broadly acute, often mucronate leaf apices are distinguishing features. The conspicuously inrolled leaf apices (when dry) separate the species from the larger M . punctatum, while M . sharpii has tuberculose basal cells and more slender leaf apices. Macromitrium microstomum, the only other autoicous Mexican species, has very slender leaves and smooth, flat upper cells.

    The type of M . richardii (at Geneva) shows that Grout correctly placed M. didymodon, M. goniopodium, M. domingense, and M . tenellum in synonymy (types also seen). I have not seen the type of M . leptophyllum, but it is probably a synonym as well. The degree of papillosity of the upper cells is variable. Some specimens have smooth, strongly bulging cells (type of M . goniopodium); others have 2-4 conic or branched papillae per cell (types of M . tenellum, M. rhabdocarpum, and M . richardii); still others have some cells papillose and others bulging-smooth (type of M . didymodon). When more specimens are available it m ay be possible to divide what we now consider M . richardii into two taxa; however, at present, recognition of one species is sufficient, as some specimens appear intermediate in papillosity and I cannot find additional correlating characters. Macromitrium richardii appears to be rare in Mexico, but most specimens seen have pluripapillose, bulging upper leaf cells and are thus easily named, as no other Mexican species has this feature.

  • Distribution

    On branches and trunks of trees and shrubs; Chiapas, Oaxaca, Puebla, Tamaulipas, Veracruz.—Mexico; Guatemala and Panama; Puerto Rico, Jamaica, and Guadeloupe; Brazil, Venezuela, Colombia, and Uruguay; Gulf Coastal Plain of eastern United States (Florida, Louisiana, and Mississippi); South Africa.

    South Africa Africa| United States of America North America| Uruguay South America| Colombia South America| Venezuela South America| Brazil South America| Guadeloupe South America| Jamaica South America| Puerto Rico South America| Panama Central America| Guatemala Central America| Mexico North America|