Monographs Details: Riccia geissleriana Jovet-Ast
Authority: Bischler, Hélène, et al. 2005. Marchantiidae. Fl. Neotrop. Monogr. 97: 1--262. (Published by NYBG Press)
Description:Species Description - Thalli in gregarious patches; lobes 7-10 mm long, 3-3.5 mm wide, rounded-truncate and crisped apically; twice forked, the basal dichotomy 5-6 mm deep, the following 1-3.5 mm; dorsal side light brown when dry, margins wavy, hyaline or violaceous; flanks tinged with violet; ventral side violaceous. Median groove deep, wide, and convex. Subepidermal cells with slightly thickened walls. Pores bounded by 4 cells. Ventral scales large, reaching lobe margins, hyaline apically, violaceous basally. Cross section of lobes 2.5-4 times as wide as high; dorsal edge acute with short wings, tinged with violet, ending in a large basal cell and a narrow, acute, terminal cell; ventral edge weakly convex; air chambers in 1 layer, partitions 3-5 cells high; ventral tissue of small, thin-walled cells. Monoecious. Archegonial necks violaceous. Sporangia numerous. Spores tetrahedral, light brown, 72-96 µm diam., wingless; distal face with 18-20 areoles across diam., each of 3-7 µm diam., convex inside, ridges without tubercles; proximal face with 3 well-distinguished facets, with 50-60 areoles per facet, areoles less regular in shape but of the same size than those of distal face, without tubercles, triradiate scar indistinct.

Discussion:Riccia geissleriana resembles R. chiapasensis by the similar lobe width, and also shows characteristics of subgen. Riccia (general habit, scale length, air chambers in single layer, simple pores). However, the air chambers are wide as in subgen. Ricciella. The simple pores, without distinct bounding cells, separate R. geissleriana from all other neotropical species of the subgen. Ricciella.
Distribution:Peru South America| Ancash Peru South America|