Leucomium strumosum (Hornsch.) Mitt.

  • Authority

    Buck, William R. 1987. Bryostephane Steereana: A Collection of Bryological Papers Presented to William Campbell Steere On The Occasion of His 80th Birthday. Mem. New York Bot. Gard. 45: 1-749.

  • Family

    Leucomiaceae

  • Scientific Name

    Leucomium strumosum (Hornsch.) Mitt.

  • Etymology

    From the Latin strumosus: provided with a swelling, in reference to its capsules which are strongly warty at base.

  • Description

    Species Description - Plants small to medium, stems creeping, but fragile and typically only 2-3 cm long. Leaves 0.9-2.9 mm long, complanate or erect-spreading, frequently secund especially at the tips; variably dimorphic (ventral leaves narrowly lanceolate, lateral leaves oblong-lanceolate to triangularly-lanceolate, dorsal leaves as in the lateral leaves or ovate to oblong-ovate) or uniform (oblong- to ovate-lanceolate) throughout, leaf apex variable (flexuose-piliferous; long, narrowly, acuminate; or long and broadly acute); margin variously inflexed on one side below; cells 60-285 yirrv x 10-50 µm, long-hexagonal, rhomboidal or linear, lax- or firm-walled, pellucid, smooth. Setae 8-20 mm long; capsules 0.3-0.8 mm, ovoid to cylindrical; exothecial cells collenchymatous; exostome teeth 0.3-0.5 mm long, dorsal surface reddish-brown, striate, usually furrowed, ventral surface yellowish-white, smooth to lightly papillose; endostome yellow, lightly papillose, equal in length to the exostome teeth, basal membrane high, segments well-developed, variously perforate, cilia absent or mdimentary; opercula 0.9-1.2 mm long, conic below, long-rostrate above. Spores 10-18 µm, yellowish, spherical, lightly papillose. Calyptrae 1.5-2.0 mm, cucullate, yellow.

  • Discussion

    Hookeria strumosa Homsch., Fl. Bras. 1(2): 69. 1840; Hypnum strumosum (Homsch.) C. Müll., Syn. 2: 238. 1851. Types: BRAZIL. Serra dos Orgaos, Feb, et prope Sebastianopolis, Beyrich; in lapidibus ibidem, Jul & Aug, Merkel; prope Tijucam, Olfers (lectotype BM, syntypes Beyrich and Merkel, not seen).

    Acosta cuspidata C. Müll, Linnaea 21: 192. 1848; Hypnum cuspidatifolium C. Müll., Syn. 2: 237. 1851, non H. cuspidatum Hedw.; Leucomium cuspidatifolium (C. Müll.) Mitt., J. Linn. Soc, BoL 12: 501. 1869; Leucomium cuspidatum (C. Müll.) Jaeg., Ber. Tatigk. St. Gallischen Naturwiss. Ges. 1877-78: 275. 1879, syn. nov. Types: SURINAM. An faulen Baustammen in Waldem bei Paramaribo, Jun 1844, Jul 1844, Feb 1844, Kegel s. n. (lectotype Jul 1844, goet; syntypes Jun 1844, goet, Feb 1844, H, NY).

    Hypnum aneurodictyon C. MuU., Syn. 2: 681. 1851; Leucomium aneurodictyon (C. Müll.) Jaeg., Ber. Tatigk. St. Gallischen Naturwiss. Ges. 1877-78: 275. 1879, syn. nov. Type: JAVA. Hb. A. Braun, Blume s.n. (holotype b, destroyed). Neotype: JAVA. Prope Depok, Holle s.n. (I, isoneotype H). Hookeria debilis Sull., Proc. Amer. Acad. Arts 3: 79. 1855; Leucomium debile (Sull.) Mitt., J. Linn. Soc, Bot. 10: 181. 1868, syn. nov. Types: FIJI [Feejee Islands]: also Samoan or Navigators' Group, growing on a fern, Wilkes s.n. (holotype fh).

    Hypnum acrophyllum Hampe, Ann. Sci. Nat. Bot. ser. 5, 5: 325. 1866; Leucomium acrophyllum (Hampe) Mitt., J. Linn. Soc, Bot. 12: 501. 1869, syn. nov. Type: COLOMBIA. Bogota: Pancho, 2000 m, in sylvis ligno adnatum, intermixtum parce legit, Jul 1863, Lindig s.n. (holotype bm, isotype NY).

    Leucomium contractile Mitt., J. Linn. Soc, Bot. 12: 502. 1869, syn. nov. Types: BRAZIL. Sierra dos Orgaos, Gardner s.n.; in sylva inter S. Paulo et Jundiahy, 2000 ft, Weir 46 (isotype bm, non g [=Acroporium]).

    Leucomium compressum Mitt., J. Linn. Soc, Bot. 12: 502. 1869, syn. nov. Types: TRINDAD. Black s.n. BRAZIL. Rumen Negro, S. Gabriel ad truncos emortuos, Spruce 803b; San Carlos, Spruce 803d; ad basin montis Cocui, Spruce 803g. PERU. Andes Peruvianae, ad fl. Huallaga in truncis. Spruce 803f lectotype Spruce 803b, ny; isolectotypes BM, FH, G, H, NY; syntypes: Black, ny; Spruce 803d, BM, G, H, NY; Spruce 803g. NY; Spruce 803f, BM, H, NY).

    Leucomium attenuatum Mitt., J. Linn. Soc, Bot. 12: 503. 1869, syn. nov. Type: ST. VINCENT. Guilding s.n. in Hb. Hooker (holotype bm, isotypes BM, NY).

    Leucomium lignicola Spruce ex Mitt., J. Linn. Soc, Bot. 12: 503. 1869, syn. nov. Types: BRAZIL. Flumen Amazon, Para, Tauau; Rio Caipuru, Spruce 803c. PERU. Andes Peruvianae, in monte Guayrapurina, 2500 ft, Spruce 803k. BRAZIL. Rio de Janeiro, Douglas s.n. (lectotype Spruce 803c pro parte (Para, Tauau), ny; isolectotypes bm, FH, G, H; syntypes: Spruce 803c pro parte (Rio Caipuru), G, NY; Spruce 803k, BM, H, NY; Douglas, NY).

    Leucomium limpidum Thwaites & Mitt, in Mitt., J. Linn. Soc, Bot. 13: 320. 1873, syn. nov. Type: SRI LANKA. Thwaites s.n. (holotype ny, isotypes BM, G, H).

    Leucomium mahorense Besch., Ann. Sci. Nat. Bot., ser. 7, 2: 97. 1885, syn. nov. Type: MAYOTTE. Sur la terre a Magi M'Bini, M'Sapere, Marie 48 (isotypes H, M, NY).

    Leucomium scabrum Besch. in Kindb., Enum. Bryin. Exot. Suppl. 2: 101. 1891, nom. nud.

    Leucomium mariei Besch., J. Bot. (Morot) 8: 178. 1894, syn. nov. Types: GUADELOUPE. Bords de la riviere Duplessis, sur les troncs d'arbres, 26 Nov 1877, Marie 519, 527, 693 (lectotype Marie 693, BM; syntypes: Marie 519, BM, Marie 527, NY).

    Leucomium mosenii Broth., Bih. Kongl. Svenska Vetensk.- Akad. Handl. 21 Afd. 3(3): 56. 1895, syn. nov. Types: BRAZIL. Minas Gerais: Caldas, in ripa umbrosa humida amnis Rio Capivary, ad terram. Mosen 264; Caldas ad rivulos, Mosen 394 (lectotype Mosen 264, h; isolectotypes bm, ny; syntypes Mosen 394, FH, H).

    Leucomium guianense C. Müll., Malpighia 10: 515. 1896, syn. nov. Type: GUYANA. Prope Georgetown ad cataractas Marshall Falls, fluvii Mazaruni, Quelch s.n. (lectotype BM, isotype NY).

    Leucomium perpellucidum C. Müll. in Par., Ind. Bryol. 765. 1896, nom. nud.

    Leucomium perglaucum C. Müll. ex Broth., Bot. Jahrb. Syst. 24: 273. 1897, syn. nov. Types: CAMEROON. An Steinen bei S. Isbel, Dusen 93; bei Bibundi, Jungner 189, 228; auf faulendem Holz bei N'dian, Dusen s.n. (lectotype Jungner 189, h; isolectotypes bm, FH, G, H, M, ny; syntypes: Dusen 93, h; Junger 228, BM, FH, G).

    Rhynchostegium molle Schimp. in Par., Ind. Bryol. 1100. 1898, nom. nud.; Leucomium molle (Schimp.) Salm. ex Par., Ind. Bryol. ed. 2, 3: 190. 1905, nom. nud.

    Leucomium golungense Gepp in Hiem., Cat. Welw. Afr. Pl. 2: 307. 1901, syn. nov. Types: ANGOLA. Golungo Alto: Alto Queta, Jun 1857, Welwitsch 191; Quisucula, Jun 1856, Welwitsch 192; Queta- Zengas, Welwitsch 191b; Capopa, Oct 1854, Welwitsch 194 (lectotype Welwitsch 191, bm; isotypes G, H; syntypes: Welwitsch 191b, bm; Welwitsch 192, BM, G; Welwitsch 194, BM).

    Leucomium connexum Ren. & Card., BuU. Soc. Roy. BoL Belgique 41: 113. 1905. Type: PUERTO RICO. Heller s.n. (isotypes H, MO, NY).

    Leucomium riparium Broth., Hedwigia 45: 288. 1906, syn. nov.; Lepidopilum laevipes Broth., Hedwigia 45: 288. 1906, nom. nud. Type: BRASIL. Amazonas: Rio Jurua, Jura Miry, am Bachufer (Ule, Bryotheca brasiliensis 264), Ule (holotype h, isotypes BM, l).

    Leucomium philippinense Broth., Philipp. J. Sci. 8: 91. 1913, syn. nov. Type: PHILIPPINES. Laguna: Calauan, McGregor 12517 (holotype h, isotypes FH, NY).

    Leucomium mouretHTher. Sc Corb., Ann. Bryol. 7:158. 1934, syn. nov. Type: MARTINIQUE. Camp de Balata, sur troncs d'arbres, 1913, Mouret s.n. (isotype H).

    Leucomium scabrum Besch. ex Ther., Ann. Bryol. 7: 159. 1934, syn. nov. Type: GUADELOUPE. (Lectotype NY, isolectotype G.)

    Sauloma africana Dix. & Ther., Rev. Bryol. Lichenol. 12: 74. 1942, syn. nov. Types: ZAIRE. Barumbu, foret, sur pierres humides Oct 1913, Bequaert 1009; Masisi, 1600 m, sur arbres, Dec 1914, Bequaert 6379 (lectotype Bequaert 1009, bm; syntype Bequaert 6379, not seen).

    Leucomium latifolium Bartr., Bryologist 49: 120. 1946, syn. nov. Type: GUATEMALA. Alta Verapaz: Cerro Chinaja, between Finca Yalpemech and Chi naja, above source of Rio San Diego, 150-700 m, Steyermark 45668 (holotype FH).

    Leucomium robustum Bartr., Bull. Brit. Mus. (Nat. Hist.), Bot. 2: 47. 1955, syn. nov. Type: DOMINICA. Morne Diablorin, windward slope, 760-900 m, Elliott 2204 (holotype bm, isotype FH).

    Nomenclatural notes. 1. Hypnum cuspidatifolium C. Müll. is a new name for Acosta cuspidata (the epithet cuspidatum being occupied in Hypnum). Mitten's use ofthe specific epithet cuspidatifolium in Leucomium (where cuspidatum was unoccupied) is therefore invalid.

    2. The type of Hypnum aneurodictyon is given as "Hb. Al. Braun." Braun's herbarium was, for the most part, destroyed during World War II. The type is no longer present at b, and in this study isotypes could not be located. There is a collection in l (Java, prope Debok, Holle), which was listed by Dozy and Molkenboer (1868) along with the type specimen under Hypnum aneurodictyon. Since both specimens are from Java, and were considered conspecific by Dozy and Molkenboer the l collection is here designated the neotype of Hypnum aneurodictyon.

    As discussed above Leucomium strumosum is incredibly variable within parts of its range. On first examination, without the benefit of examining a large number of collections, it is diflftcult to accept this taxon as a single species. Its wide variation in leaf shape and leaf dimorphism is perhaps the feature arguing most strongly for more than one species. The examination of a large number of specimens, however, shows that the variation evinced occurs along a smooth gradient: it is impossible to draw sharp lines between the expressions. Furthermore, if single, large collections of plants with strong leaf dimorphism are carefully examined, one frequently finds some plants that lack or weakly express leaf dimorphism.

    Variability in cell lengths and widths is another feature of note. Not only is this feature variable between and within collections, but within single leaves contiguous leaf cells sometimes exhibit neariy the full range of variability. For example, the following length and width measurements were made on contiguous ceUs: cell lengths—115, 200 µm (Samoa, Schultze-Motel 3769, NY), 110, 225 µm (Mayotte, Marie 114, BM), 150, 235 µm (Ivory Coast, Assel 189, MO), 115, 240 µm (Brazil, Dusen s.n., NY); cell widths—20, 35 µm (Ivory Coast, Assel 189, MO), 12, 32 µm (Venezuela, Steyermark 75147, FH). The calyptrae in L. strumosum may be sparsely hairy (as in the type collection) or naked. Previously, a number of Leucomium species have been described principally on the basis of their naked calyptrae. Although sparsely hairy calyptrae are found only in collections from the New World, in this region the feature is erratic in occurrence and does not appear correlated with any other unusual feature in the genus. Sporophytically, seta length and upper ornamentation (i.e., warty or smooth at apex), capsule shape and orientation, and the degree of furrowing on the dorsal surface of the exostome are features that vary widely, but inconsistently. Leucomium strumosum appears to be a common species in the tropical regions ofthe world. It frequently occurs as a few stems intertwined with a host of other mosses and liverworts on fallen logs and rotten bark and wood. As such it is frequently overlooked; as noted by Whittier (1976), "this species is much more common than my own records would suggest, and appears frequently in admixtures with other bryophytes."

    In this study, very few collections were found to be generically misdetermined, since even collections apparently lacking plants of Leucomium on careful examination yielded at least a few stems of Leucomium.

    As noted above, there are three distinctive expressions of Leucomium strumosum in South America. These expressions, may be distinguished.