The occurrence in southern Africa of the hepatic , Symphyogyna brasiliensis ( Pallaviciniaceae )

In Magill & Schelpe (1979) Symphyogyna lehmanniana is confirmed as occurring in southern Africa. Subsequently, however. Grolle (1980) reported that this name, which has been applied to a liverwort widespread in Africa, is a synonym of S. brasiliensis. To draw attention to this synonymy, a description of S. brasiliensis, illustrated with photographs, is given here, as well as an account of its distinguishing features and its distribution.


INTRODUCTION
In Magill and Schelpe's (1979) checklist, Symphyogyna lehmanniana is listed as one of the species of Symphyo gyna occurring in southern Africa.
Subsequently, however, Grolle (1980) concluded that this name, applied to a liverwort reported to be widespread in Africa, is a synonym of S. brasiliensis.During the course of his investigations Grolle had compared speci mens assigned to both species, their types, as well as spores, and could find no differences.He had also examined a number of other specimens, previously assigned to several so-called different species of Symphyo gyna and Pallavicinia, all of which he eventually placed in synonymy under S. brasiliensis.Three of these species, namely S. lehmanniana, S. valida and Pallavicinia capensis, have types which were collected in southern Africa.The following description of S. brasiliensis, which is illustrated with photographs, is given to draw attention to the above information.
The two Metzgerialean genera, Symphyogyna and Pallavicinia were previously placed in the family Dilaenaceae (Dum.)Warnst.by Arnell (1963) and by Schuster (1964Schuster ( , 1982)), but this name is illegitimate (Grolle 1972).They are now classified by Grolle (1983) in the family Pallaviciniaceae Migula and are placed in different subfamilies, the Symphyogynoideae (Trev.)Schust.and the Pallavicinioideae (Migula) Grolle respectively.They are frondose liverworts, characterized by thinly winged thalli with a thicker midrib, containing a median con ducting strand of elongate, tapering cells with thickened, perforated walls.The thalli are often stipitate and are either procumbent or erect; their margins are entire, dentate, undulate or lobate; the epidermal cells are ± rectangular and lack nodular thickenings and the capsules are elongated.The two genera are separated by the type of pro tection provided for the archegonia and young sporophyte: in Pallaxicinia the archegonia, and after fertilization, the pseudoperianth and capsule, are surrounded by a short tubular or annular involucre; in Symphyogyna the arche gonia are subtended by a laciniate, scale-like involucre with the margins of the latter free and directed forward, no pseudoperianth is developed after fertilization and the young sporophyte is enclosed only by the shoot-calyptra, which has a cluster of unfertilized archegonia at its tip.Terricolous, growing on damp soil; thallose, prostrate and creeping (Figures 1A; 2B), in crowded, overlying mats, bright green when fresh, rarely developing a purplish or reddish tinge along margins and over costa, linear, simple or dichotomously branched, sometimes with ventral intercalary branching, medium-sized to large, 10-20 x 2 -3 mm, 280 nm thick over ventrally bulging costa, from which arise pale brownish, translucent rhizoids, smooth and mostly ±12.  .Costa with a central conducting strand (Figure 1C), ± 45 /xm wide, brownish to purple, formed of strongly elongated, small cells, ± 10.0 x 7.5 /xm, with straight, thickened walls, the enclosing cells up to 10 or 11 rows deep, hyaline, much larger, mostly 50.0 x 27.5 /xm, irregular in shape, walls thin and wavy.

FIGURE l.S y m p h y o g y n a bras i liens is
Dioicous.Androecia usually in 2 crowded (Figure 1A), more or less parallel rows over the costa and lateral to it on either side, each short-stalked antheridium (Figure IE) partially covered by an irregularly shaped, dentate or en tire, forwardly-directed, scale-like involucre (Figure 1G), ± 800 x 450 /xm, its cells mostly 67.5 x 45.0 /xm, with age antheridia turn yellow and cell walls of scales dar ken.Gynoecia generally one to several per frond, in acropetal succession, situated dorsally over the costa and containing several archegonia in a cluster (Figure 1A), which is subtended by a posteriorly inserted, scale-like involucre (Figure 2B), sometimes partly double toward the base, generally deeply laciniate (Figure 3A), 850-110 x 500-750/xm, its cells ± 72.5 x 50.0/xm.Calyptra thick ening and enlarging into a fleshy shoot-calyptra, up to 3 mm long and as much as 10 cell rows or 260 /xm thick in cross section (Figure 2G), with several unfertilized archegonia at the tip (Figure 2C), before it is perforated by the capsule (Figure 2D).Capsule cylindrical (Figure 2E), 2250 x 650 /xm, opening with 4 valves, wall brown, several cell layers thick, outer cells irregularly elongate (Figure 3B), ± 200 x 20-30 /xm, with cell walls evenly thickened (Figure 3D), inner cells thin-walled.Seta when young, erect, ± 290 /xm in diameter, with ± 18 cortical cell rows and ± 16 medullary cells (Figure 2F), eventually becoming long and tenuous (Figure 2E).Spores light brown, ± globular, 2 5 -3 0 /xm in diameter, ornamenta tion with low, irregularly branched, short or long, curly ridges (Figure 3E, G, H), on proximal face a discrete round area with the ornamentation much more densely arranged (Figure 3F).Elaters bright brown, tapering to the ends, up to 195 X 7.5 /xm wide in the centre, 2-spiral (Figure 3C, J).
Gradstein et al. (1983) reported it to be widely distributed in the tropical mountains of the two continents.Africa and South America, at altitudes between 1 500 and 3 000 m. whereas in subtropical Brazil, the Cape Province and on the Galapagos Islands it descends to near sea level.
In southern Africa it has been collected in northern, eastern, central and southern Transvaal, in Swaziland.Natal and Zululand, as well as in the southwestern and southern Cape (Figure 4).Symphyogyna brasiliensis is terrestrial, growing on damp streambanks.along footpaths or in forested areas.It differs from the other species in the genus by its procum bent habit, by the entire margins of the thallus, by its slightly larger spore size and by its somewhat finer spore ornamentation.S. filicum Nadeaud from Cameroon Moun tain is similar to 5. brasiliensis, except that the small cells in the central strand are thin-walled (Jones 1990) and the spore sculpture is different.It was recently segregated as a separate genus, Symphyogynopsis, by Grolle in Grolle & Piippo (1986).Symphyogyna volkensii Steph. is more robust (Vanden Berghen 1965) than S. brasiliensis and has scattered slime papillae along the wing margins and different spore ornamentation (Grolle pers. comm.).
As vegetative propagation is unknown, dispersal of S. brasiliensis must be by long range aerial transport of its spores.Its presence on young volcanic islands would support this assumption.
FIGURE 1.-Symphyogyna brasiliensis.A, male thallus with androecia; B, apical notch of thallus with slime papillae (indicated by an arrow); C, cross section of thallus showing costa with central conducting strand and unistratose lateral wings; D, marginal and laminal cells seen from above; E, antheridium; F, oil bodies and chloroplasts visible inside cells; G, scale-like involucre which partly covers antheridium.A -G , Glen 2687.A, x 22; B, F, x 350; C, E, G, x 87; D, x 175.
FIGURE l.S y m p h y o g y n a bras i liens isA, female thallus with cluster of archegonia; B -E , various stages in maturation of capsule: B, C\ young capsule enclosed in calyptra; D, capsule and seta emerged from calyptra; E, capsule with ripe spores and long, tenuous seta; F, cross section o f seta; G, cross section through middle of shoot-calyptra.A -G , Glen 2687.A, B, E, x 24; C, x 34; D, x 30; F, X IK); G, x 40.