Riccia elliottii Steph.
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Authority
Bischler, Hélène, et al. 2005. Marchantiidae. Fl. Neotrop. Monogr. 97: 1--262. (Published by NYBG Press)
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Family
Ricciaceae
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Scientific Name
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Type
Type. Windward Islands. Dominica. Elliott 984 (holotype, G; isotype, BM).
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Description
Species Description - Thalli in irregular, gregarious mats; lobes 2-3 times forked, 8 mm long, 1.5-2 mm wide, thin, rounded, and slightly emarginate apically; dorsal side light brown or greenish brown when dry, light green when moist, with narrow, hyaline, slightly undulate margins; ventral side brown, violaceous-brown or reddish. Median groove deep apically, vanishing rapidly below. Epidermal cells disintegrating except in groove, rounded. Ventral scales not seen. Cross section of lobes 2-6 times as wide as high; dorsal edge acute laterally with hyaline wings; flanks obliquely ascending; ventral edge convex; dorsal tissue in 3-4 layers. Monoecious. Spores tetrahedral, 80-90 µm diam., red-brown; wing 4 µm wide, light brown, granulose; distal face with 4-5(-6) areoles across diam., granulose inside, with high, red-brown or nearly black ridges and large tubercles; proximal face with 3-6 areoles per facet, larger than those of distal face, with high, narrow ridges at pole, with lower ridges and weak tubercles, progressively vanishing toward equator, triradiate scar weak.
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Discussion
Riccia elliottii is allied to R. breutelii and R. brittonii. However, it differs from these two species by its thallus characteristics (see description) and by the spore wall ornamentation, with a smaller number of areoles across the distal and proximal faces.
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Distribution
Riccia elliottii has been recorded from Mexico (Jalisco (Howe, 1934)), Costa Rica (Howe, 1934), and the Windward Islands (Dominica). Whether the records from the Virgin Islands (St. Thomas (Pagan, 1939)) and Puerto Rico (Mona Is. (Pagan, 1939)) belong to this species remains questionable.
Dominica South America|