Monographs Details: Riccia weinionis Steph.
Authority: Bischler, Hélène, et al. 2005. Marchantiidae. Fl. Neotrop. Monogr. 97: 1--262. (Published by NYBG Press)
Family:Ricciaceae
Scientific Name:Riccia weinionis Steph.
Synonyms:Riccia corcovadensis Steph.
Description:Species Description - Thalli in gregarious patches; lobes 5-6 times forked, 10-25 mm long, 2-3 mm wide, rounded apically; dorsal side grayish green or whitish when dry, green or blue-green when moist, margins narrow, light green or whitish, acute; flanks tinged with pink, or violet, or black, inflexed when dry; ventral side light green. Median groove deep apically, vanishing progressively toward base. Epidermal cells disintegrating except in groove, rounded. Ventral scales distant, not reaching lobe margins, pink-violet or violet, cells 60-85 × 25-36 µm, margins with 2 rows of long narrow cells. Cross section of lobes 3-5 times as wide as high; dorsal edge acute laterally with short wings, ending in 2-3 hyaline cells and in a terminal, hyaline, long, acute cell with thickened walls; flanks obliquely ascending and slightly arched; ventral edge convex; dorsal tissue 1/3-1/2 of lobe height, in 4-5 layers, cell walls with 2 longitudinal, partly anastomosed, thickened strips; cells of ventral tissue thin-walled, sometimes pitted. Monoecious. Antheridial necks hyaline, protruding, 80-170 µm long. Sporangia numerous, large, bulging dorsally. Spores tetrahedral, 90-145 µm diam., red-brown to black-red, wingless but with lighter, granulose border; distal face with 7-9 areoles across diam., with blackish ridges and large, often coalescent tubercles; proximal face with few complete areoles with thin ridges and tubercles, or with incomplete, irregular areoles with interrupted ridges, triradiate scar weak or nearly indistinct. Gametophytic chromosome number n = 8.

Discussion:Riccia weinionis belongs to a group of species characterized by cells of the dorsal tissue with longitudinal thickenings (R. ridleyi, R. vitalii, R. weinionis). The species of this group are readily distinguished by spore wall ornamentation (see under R. vitalii). Moreover, in R. vitalii the thallus lobes are narrower (1-2.3 mm) and the pink or violet scales extend beyond lobe margins; in R. weinionis the thallus lobes are wider (2-3 mm), with pale margins, and the scales are shorter and do not pass beyond the lobe margins.

Distribution and Ecology: Riccia weinionis is known from Mexico (D. F., Mexico, Oaxaca), Costa Rica, Panama, Leeward Islands (Saint-Barthélémy), Windward Islands (La Desirade, Les Saintes, Martinique, Guadeloupe (Jovet-Ast, 1959)), S Dutch Antilles (Bonaire, Curaçao), Colombia (Magdalena), and Brazil (Bahía, Cearà, Espíritu Santo, Goiás, Mato Grosso, Minas Gerais, Paraíba, Paraná, Rio de Janeiro, São Paulo, Sergipe). The species seems to be quite common; it has been collected on soil or rocky soil, or on thin layer of soil over rocks (lava, granite, limestone, sandstone, stone walls), exposed on boulders, along streams, and in gardens, or shaded beneath shrubs or around tree bases in deciduous or evergreen woodlands, from sea level to 2300 m.

Distribution:São Paulo Brazil South America| Paraíba Brazil South America| Goiás Brazil South America| Mato Grosso Brazil South America| Bahia Brazil South America| Rio de Janeiro Brazil South America| Sergipe Brazil South America| Espirito Santo Brazil South America| Minas Gerais Brazil South America| Ceará Brazil South America| Paraná Brazil South America| Bonaire South America| Martinique South America| Curaçao South America| Distrito Federal Mexico North America| México Mexico North America| Oaxaca Mexico North America| Chiriquí Panamá Central America| Guanacaste Costa Rica Central America| Magdalena Colombia South America| Costa Rica South America| Saint Barthélemy South America| Pointe-à-Pitre Guadeloupe South America| Guadeloupe South America|