Studies in the genus Riccia (Marchantiales) from southern Africa. 15. R. hirsuta and R. tomentosa, sp. nov., two distinct species previously treated as one

Abstract

The description of Riccia hirsuta (Volk & Perold 1986) is emended and new illustrations of the species are provided, as the original description and illustrations were based on  two distinct, but rather similar species. Examination of newly collected material of R. hirsuta, showed it to belong to subgenus Riccia, section Pilifer (Volk 1983). Section Micantes (Volk & Perold 1986) of which this was the type species, is therefore transferred to section Pilifer. R. tomentosa Volk & Perold, sp. nov., described here, is at first glance somewhat similar to R. hirsuta in its habit, hence the earlier confusion in Volk & Perold (1986). It also resembles R. hirsuta in its dorsal covering of long hairs and in the triangular scales apically split into cellular strands. R. tomentosa, however, differs from R. hirsuta in the spongy (not compact) construction of the thallus and in the spores permanently united in tetrads (not single). It belongs to subgenus  Thallocarpus and is the type species of the new section Pannosae.