Didymodon tophaceus (Brid.) Lisa

  • Authority

    Sharp, Aaron J., et al. 1994. The Moss Flora of Mexico. Part One: Sphagnales to Bryales. Mem. New York Bot. Gard. 69 (1): 1-452.

  • Family

    Pottiaceae

  • Scientific Name

    Didymodon tophaceus (Brid.) Lisa

  • Description

    Species Description - Plants green or olive-green above, tan below. Stems irregularly branched, up to 15 mm high. Leaves when dry spreading to 45° or occasionally ± erect, when moist spreading, broadly concave to keeled, 1-2 mm long, ligulate to ovatelanceolate, broadly acute to obtuse or rounded, ovate at base and usually broadly decurrent; margins weakly recurved in the lower 3/4, entire or occasionally crenulate at the apex, occasionally thickened in spots; costa often dark-brown, percurrent or ending as much as 6 cells below the apex, occasionally short-excurrent, covered ventrally by rectangular cells and dorsally by quadrate or rectangular cells, the ventral stereids none or substereid, the dorsal stereid band weak or absent; upper cells oval to rhombic or triangular, (7—)9—12(-14) µm wide, 1-2:1 (often transversely elongate), with papillae low, broad, simple, with 1-2 salients per lumen on both surfaces, sometimes apparently absent; basal cells little differentiated, 10-12 µm wide and 1-2:1. Setae 7-9 mm long; capsules 0.6-1.3 mm long, ovoid to short-cylindric, occasionally oblique-mouthed; operculum 1-1.2 mm long, high-conic, with cells in straight rows; peristome none, rudimentary, or short, up to 220 µm long, cleft nearly to the base, occasionally perforated below, straight, light-yellow, spiculose to papillose. Spores 12-14(-20) µm, weakly papillose.

  • Discussion

    Fig. 232

    D. tophaceus (Brid.) Lisa, Elencho Muschi Torino 3. 1837.

    Trichostomum tophaceum Brid., Muscol. Recent. Suppl. 4: 84. 1819.

    Barbula tophacea (Brid.) Mitt., J. Linn. Soc, Bot. Suppl. 1: 34. 1859.

    Dactylhymeniumpringlei Card., Rev. Bryol. 36. 72. 1909.

    Barbula abboniiTher., Smithsonian Misc. Collect. 85(4): 20. 1931.

    B. pringlei (Card.) Hilp., Beih. Bot. Centralbl. 50(2): 645.1933, horn. illeg., non Card., 1909.

    Husnotiella pringlei (Card.) Grout, Moss Fl. N. Amer. 1: 219. 1939.

    The broad decurrencies, usually best developed in large plants, may be lacking in smaller ones. The type material of Barbula abbonii shows small, mid-basal lamellae at the back of many leaves, a feature not observed in other specimens assigned to Didymodon tophaceus.

    Didymodon vinealis var. luridus has some similarity to D. tophaceus, and care should be exercised to avoid confusion.

  • Distribution

    On wet, calcareous soil or rock at edges of springs or streams, 1100-2200 m elev.; Baja California, Chiapas, Chihuahua, Coahuila, Distrito Federal, Durango, Hidalgo, Jalisco, Mexico, Morelos, Nuevo Leon, Puebla, San Luis Potosi, Sonora.—Mexico to South America; North America; Europe; Africa; Asia

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