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.
Highlights
When R. hirsuta Volk & Perold (1986), the figures of which are referred to below as 1986, was described, it was assumed that all five specimens listed under this species, definitely belonged here
Examination of newly collected material of R. hirsuta, showed it to belong to subgenus Riccia, section Pilifer (Volk 1983)
Even though there were some indications that the material was not quite homogeneous, the possibility of another, rather similar species, existing in the same area seemed remote, and it was assumed that all material belonged to one species
Summary
When R. hirsuta Volk & Perold (1986), the figures of which are referred to below as 1986, was described, it was assumed that all five specimens listed under this species, definitely belonged here Among these specimens, only Oliver 8040 had mature spores. During fieldwork by Perold in Namaqualand in September/October 1987 and August/September 1988 and by Oliver in July 1989, six new collections of densely hairy specimens were made, each one with distinctly papillose spores which on maturity remain in permanent, ± globular tetrahedral tetrads. These collections belong to a new species, R. tomentosa (see below). Thallus monoicous (?), perennial, scattered, not in rosettes, dorsal surface hirsute with thick pelt of shiny hairs (Figure 2A), whitish along margins, greenish grey over centre; medium-sized to large (Figures 1A, C; 1986: 1A); branches simple or bifurcate, up to 10 mm long, 2,0-4,0 mm wide, 1,5-2,0 mm thick, i.e. about once to twice wider than thick; oblong, broadening towards truncate apex (Figure 2B); groove short, soon becoming flat; margins subacute; flanks sloping outwards in a short wing (Figure ID), greyish green, occasionally with some reddish pur ple flecks; ventral surface slightly rounded to plane, pale green; when dry (Figure IB), sides partly inflexed, dorsal surface grey, dusty from accumulation of sand grains trapped between hairs
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