Studies in the genus Riccia ( Marchantiales ) from southern Africa . 22 . R . rubricollis , now validated , typified and described

Riccia rubricollis is a very rare endemic species, only known from a few collections by Duthie at Knysna. Unfortunately she and Garside did not publish anything on it, and Arnell's (1963) description has neither a Latin diagnosis nor was a type specimen cited. These omissions have now been rectified here, following the recent rediscovery of Duthie's collections

T Y P E .-Cape,3423 (Knysna): Knysna.Belvidere, on turf in shady places, not far from lagoon (-A A ), Sept./Oct.1929.Duthie 5014 (BOL. lecto.; PRE. isolecto.)Riccia rubricollis is known only from Knysna in the southern Cape, where it was collected on a few occasions by Duthie (Figure 1).It has so far not been found else where in southern Africa.It grows at low altitude, in damp, shady places, with R. purpurascens Lehm.& Lindenb., Fossombronia sp. and Pleuridium sp.The rainfall is 600 -800 mm per year and may occur all year round.Thallus dioicous, .'perennial, in gregarious patches (Figure 3A) sometimes with branches overlying, or scattered, not in rosettes, yellowish green, occasionally with some purple blotches; branches once (Figure 2A) or twice symmetrically or asymmetrically furcate, rarely simple, and then apically bilobed.moderately to widely divergent, up to 12,0 mm long, segments 2 ,5 -6 ,0 x 2.8-3.0 mm.0.7-1.0mm thick medianiy, thinner toward winged margins, in section 2 -4 times wider than thick; oblong or somewhat linear as in species of section Ric ciella.tapered toward apex (Figure 3C); groove deep only at apex, soon shallow and wide; margins subacute, rather irregularly undulating, winged; flanks sloping obliquely to very obliquely, yellowish; ventrally rounded or median iy keeled; when dry. margins not inflexed, somewhat raised, straw-coloured to light brown, dorsally pitted in older parts.
Antheridia in a row along midline of male thalli, when mature bulging dorsally, with conspicuous, mostly dark purple necks (Figure 2B), up to 300 x 25 /xm.Archegonia 3 or 4 serially arranged toward base, necks purple, thin, hidden.Sporangia up to 1100 /xm wide, deeply imbedded, not bulging dorsally or ventrally, but eventually opening to upper surface, containing ± 620 spores each.Spores 92 -100(-105) /xm in diameter, triangular-globular, polar, reddish brown to deep russet-brown, semitransparent to opaque; wing 5 /xm wide, wider and perforated at marginal angles (Figure 4E), and often perforated elsewhere too, margin finely crenulate, slightly undulating; ornamenta tion completely or incompletely reticulate, rather different on 2 spore faces: distal face (Figure 4C, F) with 5 or 6 areolae across diameter, central ones larger, 2 0 -2 5 /xm wide, toward margin smaller, 10 /xm wide, walls ± 4 /xm thick and 6 /xm deep, shallower laterally (Figure 4D), not raised at nodes (Figure 4E); proximal face with triradiate mark prominent (Figure 4A), widening toward marginal angles at junction with wing (Figure 4B), areolae up to 12 /xm wide, mostly incomplete, walls slightly raised at nodes.Chromosome number: unknown, as living material not available.This species is characterized by ± linear, apically tapering branches, which, in the male plants, bear a single median row of conspicuous, deep purple antheridial necks.Stolons are confined to the thickened perennating tips of some branches (Figure 3B).Although more robust and fleshy, R. rubricollis is clearly related to R. purpurascens Lehm.& Lindenb., because of its somewhat linear habit, but it is not classified together with it and R. stricta (Lindenb.)Perold in section Ricciella (subgenus Ricci el la), as the sporangia do not conspicuously bulge ventrally.Na-Thalang (1980) regards the Australian species R. collata, as having the closest affinity to R. rubricollis, although the latter plant is larger and on the distal spore face, the areolae are wider.
The specific epithet, R. rubraosteolata, in Duthie's handwriting, appears on the labels of her collections, one of which she kept in cultivation for some time at Stellenbosch, but unfortunately she and Garside did not publish a description of this rare, endemic species.Amell's (1963) illustrations are reported to be after Garside, but the originals have not been traced.Arnell eventually described the species under the name, R. rubricollis, but did not give a Latin diagnosis and cited no specimens,  He had, however, assured me that there were no such specimens held at BOL.In my study (Perold 1989) of the spore wall ornamentation as an aid in identifying southern African species of Riccia, I therefore mistakenly stated that there are no examples of R. rubricollis.
The largest collection of this species, Duthie 5014, con sists of two packets; one of them is selected here as the lectotype and is held at BOL; the duplicate specimen, the isolectotype, is held at PRE.
FIGURE 1. -Distribution of R. rubricollis in southern Africa.