Thuidium tomentosum Schimp. ex Besch.

  • Authority

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

  • Family

    Thuidiaceae

  • Scientific Name

    Thuidium tomentosum Schimp. ex Besch.

  • Description

    Species Description - Plants medium-sized to robust, in often large, lax, mostly dull-green mats. Stems mostly ± arched, to ca. 10 cm long, 2-3-pinnate, ± frondose; in cross-section with 3-5 rows of small thick-walled greenish cells surrounding gradually larger and somewhat thinner-walled cells, central strand small, of very small cells, paraphyllia abundant on stems and primary branches, few or none on secondary and tertiary branches, polymorphous, mostly uniseriate but branched, some foliose with uniseriate filaments, the cells oblate to subquadrate, ca. 0.8-1.3:1, papillose, with papillae on almost all cells and not restricted to cell ends; pseudoparaphyllia foliose; axillary hairs with a single short brown basal cell and 2 elongate hyaline distal cells. Stem and branch leaves strongly differentiated, stem leaves appressed when dry, spreading when moist, broadly ovate to triangular-ovate, 0.6-1 mm long, ± abruptly acuminate, concave, not or scarcely plicate, short-decurrent; margins papillose-serrulate throughout, recurved throughout except in upper 1/2 of acumen; costa single, strong, ending ca. >4/5 the leaf length, ending in but not filling the acumen, papillose, in lower 1/3 sometimes with small paraphyllia; cells round to oval to subquadrate, mostly 1-1.5(-3): 1, pluripapillose with (1-)2-3(-4) papillae centrally located over the lumina, firm-walled, not porose; alar cells not differentiated but cells in 2-3 rows across the insertion rectangular, thick-walled, porose, and smooth. Secondary and tertiary branch leaves erect when dry, spreading when moist, lanceolate-ovate to ovate, 0.2-0.25 mm long, acute, concave, not plicate, not decurrent; margins papillose-serrulate, plane; costa single, usually ending 1/2(-2/3) the leaf length, often forked above; cells oval to irregularly isodiametric, ca. 6 µm wide, pluripapillose with (l-)2-3(-4) papillae centrally located over the lumina, the papillae usually low, slightly curved, thin- to firm-walled, the apical cell truncate and crowned with 2-5 papillae; alar cells not differentiated. Asexual propagula none. Dioicous. Perichaetial leaves mostly erect, narrowly lanceolate, ca. 4 mm long, long-loriform and often the apex >1/2 the leaf length, not plicate; margins serrulate in the acumen, ciliate at base of the acumen, the cilia uniseriate except at their extreme bases, entire below, plane; costa single, ending in the base of the acumen; cells long-rectangular in the acumen, linear below, smooth, thick-walled, porose. Setae elongate, stout, smooth, reddish, 2.5-3 cm long; capsules horizontal, asymmetric and ± arcuate, cylindric, ca. 2 mm long; exothecial cells subquadrate, ± thin-walled; annulus and operculum not seen; exostome teeth yellow to yellow-brown, shouldered, bordered, on the front surface cross-striolate below, with overlying papillae, then finely papillose, then coarsely papillose at apex, trabeculate at back; endostome with a high, smooth basal membrane, segments finely papillose, keeled, not or very narrowly perforate, cilia finely papillose, in groups of 2-3, appendiculate. Spores spherical, finely papillose, 13-17 µm diam. Calyptrae not seen.

  • Discussion

    5. Thuidium tomentosum Schimp. ex Besch., Mém. Soc. Sci. Nat. Cherbourg 16: 237. 1872. Plate 73, figures 11-21 Thuidium antillarum Besch., Ann. Sci. Nat. Bot. VI, 3: 244. 1876. Discussion. Thuidium tomentosum is the only member of the genus in the West Indies and perhaps all the American tropics with pluripapillose laminal cells. It differs from the pluripapillose species of Cyrto-hypnum by the larger plant size with large, branched paraphyllia, with the papillae of the laminal cells being centrally located over the cell lumina (rather than around the periphery). Thuidium tomentosum seems most closely related to T. urceolatum and may be the Lesser Antillean vicariant of it. Both have similar leaf areolation and one also encounters some scattered cells in leaves of T. urceolatum with two papillae over the lumina. Although I have found no other tropical American species of Thuidium with pluripapillose cells, there may be some undescribed taxa—or at least specimens with variation outside that found in the West Indies. For example, a specimen from 1450 m in Bolivia (Nee & Coimbra S. 35240, NY) has cells with each of the several papillae/cell bifid as well as other minor morphological differences from typical T. tomentosum. Bifid papillae are common in some forms of T. delicatulum, but I have not otherwise seen it in T. tomentosum.

  • Distribution

    Range. Mexico and Central America, northern South America; Cuba (rare), Hispaniola (Dominican Republic), Saba, St. Eustatius, St. Kitts, Nevis, Montserrat, Guadeloupe, Dominica, Martinique, St. Lucia, St. Vincent, Grenada; growing over soil or humus, in mesic to moist forests or relatively exposed areas, at mostly 300-1500 m. Gier’s (1980: 268) report of the species from Puerto Rico (Heller s.n., MO) is based on a specimen of T. urceolatum.

    Mexico North America| Central America| Venezuela South America| Colombia South America| Brazil South America| Ecuador South America| Guyana South America| Suriname South America| French Guiana South America| Cuba South America| Dominican Republic South America| Saba South America| Sint Eustatius South America| Saint Kitts and Nevis South America| Montserrat South America| Guadeloupe South America| Dominica South America| Martinique South America| Saint Lucia South America| Saint Vincent and the Grenadines South America| Grenada South America|