Monographs Details: Riccia horrida Jovet-Ast
Authority: Bischler, Hélène, et al. 2005. Marchantiidae. Fl. Neotrop. Monogr. 97: 1--262. (Published by NYBG Press)
Scientific Name:Riccia horrida Jovet-Ast
Description:Species Description - Thalli forming rosettes of 12 mm diam.; lobes 2-3 times forked, 3-6 mm long, 0.8 mm wide, rounded apically; dorsal side light green or light brown; flanks violet. Median groove wide. Epidermal cells disintegrating. Ventral scales violaceous, not extending beyond lobe margins. Cilia numerous, inserted on top of flanks and on lobe margins, sometimes in groove, some short (less than 100 µm long), smooth, most granulose, to 240 µm long, both types acute, stiff, erect or oblique, some intercrossing over the lobes. Cross section of lobes 0.4 mm high at apex, 0.2-0.3 µm near base; dorsal edge rounded laterally; flanks ascending; ventral edge convex. Dioecious? Spores spherical or tetrahedral, 74-86 µm diam., red-brown with red-brown or dark red-brown ornamentation; wing 7 µm wide, 12-15 µm wide near the pores, slightly papillose and crenulate on margin, pores bounded by a triangular, smooth area; distal face with 8-9 areoles across diam., each of 6-8 µm diam., with rather thin ridges and weak tubercles; proximal face with numerous, smaller areoles, with thin ridges and small tubercles, triradiate scar weak.

Discussion:The abundance of cilia distinguishes Riccia horrida from all other neotropical Riccia species. The cilia are of two types, smooth ones to 100 µm long and granulose ones to 240 µm long. The scales are violaceous. The spores are rather small, 74-86 µm in diam., and have a characteristic, smooth triangular area bounding the pores on the proximal face. The latter characteristic is shared with R. subdepilata but this species has less abundant and exclusively granulose, 120-380 µm long cilia, colorless scales, and larger spores (84-96 µm).
Distribution:Espirito Santo Brazil South America|