Ricciocarpos natans (L.) Corda

  • Authority

    Bischler, Hélène, et al. 2005. Marchantiidae. Fl. Neotrop. Monogr. 97: 1--262. (Published by NYBG Press)

  • Family

    Ricciaceae

  • Scientific Name

    Ricciocarpos natans (L.) Corda

  • Type

    Type (Grolle, 1976). Europe. Great Britain: Suffolk, near Hadley, Buddie s.n. (holotype, OXF, n.v.; isotype, H-SOL, n.v.).

  • Synonyms

    Ricciocarpos velutinus (Hook.f. ex Wilson) Steph., Riccia natans L., Ricciocarpos velutinus (Hook.f. ex Wilson) Steph., Riccia velutina Wilson

  • Description

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    Species Description - Thallus yellow-green to green, often tinged with purple, forming hemi-rosettes or rosettes, segments 2-5 mm wide, with groove apically. Epidermis well developed, often with oil cells. Epidermal pores with single ring of 4-8 cells, radial walls thin. Air chambers in 2 to several layers. Ventral tissue in 3-4 layers, with oil cells. Ventral scales usually purplish, in several ill-defined, transverse rows, very long in floating forms, shorter in terrestrial, with oil cells, without marginal papillae, margins serrulate. Asexual reproduction by specialized propagules lacking. Monoecious. Antheridia in dorsal groove along thallus midline. Archegonia in 2-3 rows in dorsal groove. Spores ca. 450 per capsule, 42-72 (im diam., proximal and distal faces with ± complete, tuberculate areoles and tuberculate ridges, trilete scar distinct. Gametophytic chromosome number n = 9.

  • Discussion

    Ricciocarpos natans grows floating on stagnant water, at the margins of temporary ponds, streams, and in swamps, or on very wet soil. It is rare everywhere and has rarely been seen with sporophytes. The species is not drought-tolerant but is probably able to shorten its life cycle to a few weeks. It seems to be absent from areas with long, cold winters. In the Neotropics, R. natans has been collected from sea level to 2800 m.

    The main diagnostic feature distinguishing Ricciocarpos natans from other Marchantiales are the scales with serrulate margins. In terrestrial populations the scales are short and wide, whereas in floating populations they are very long and often slender. Aquatic populations of R. natans have sometimes been distinguished taxonomically from terrestrial ones, but other diagnostic characters have not been found. In the Neotropics, Ricciocarpos velutinus, R. natans var. brasiliensis, and R. natans fo. terricola belong to the terrestrial form.

    Distribution and Ecology: The distribution of the species is worldwide in the N and S hemispheres, from 62°N to 45°S (Europe, the Mediterranean area, tropical and temperate Africa, SW Asia, N Asia, India, China, Japan, Australia, and New Zealand), and includes Canada, U.S.A. (recorded from 35 states), and C and S America. In the Neotropics it is known from Mexico (Jalisco, Mexico, Morelos, San Luis Potosí, Tabasco), Panama, Venezuela (Infante-Sanchez & Heras Pérez, 2002), Brazil (Amazonas, Bahía (Yano, 1981b), Espíritu Santo (Yano, 1981b), Pará, Paraná (Yano, 1989), Pernambuco (Porto & Yano, 1985), Rio Grande do Sul, Santa Catarina (Yano, 1981b; Vianna, 1976), São Paulo), Bolivia, Chile (Valparaiso), Argentina (Buenos Aires, Formosa, Entre Ríos (all recorded by Hässel de Menéndez, 1963)), and Uruguay; perhaps also from Cuba (Howe, 1923).

  • Distribution

    Amazonas Brazil South America| Pará Brazil South America| São Paulo Brazil South America| Mato Grosso Brazil South America| Rio Grande do Sul Brazil South America| San Luis Potosí Mexico North America| Morelos Mexico North America| Jalisco Mexico North America| Tabasco Mexico North America| Valparaíso Chile South America| Loreto Peru South America| Brazil South America| Panamá Panama Central America| Santa Cruz Bolivia South America| San José Uruguay South America| Panama Central America|