Studies in the liverwort genus Fossombronia ( Metzgeriales ) from southern Africa , 1 . Three new species from Northern Province , Gauteng and Mpu malanga

Three new species of Fossombronia from Northern Province, Gauteng and Mpumalanga (formerly Transvaal) are described: F. gemmifera, F. glenii and F. straussiana. F. gemmifera is distinguished by a highly convoluted pseudoperianth, the frequent presence of gemmae produced dorsally on the stem, lamellate spores and mostly rather short elaters; F. glenii can be recognized by a smallish, deeply lobed pseudoperianth, perigonial bracts with finger-like projections shielding the antheridia and by spinous spores; F. straussiana is distinct by its hyaline or brownish rhizoids, by its dense, frilly leaves, its pseudoperianth with lamellate lateral outgrowths, by spore ornamentation that usually has inclusions in the incomplete areolae and by the elaters which are

Plants of the genus Fossombronia are small, usually gregarious with mostly prostrate, fleshy stems, laterally bearing succubously inserted, undulating or crisped thallus wings, dissected into leaf-like segments and free to the base, where they are bistratose, but unistratose elsewhere.The stems are anchored to the substrate by rhizoids which are usually purple, but hyaline in a few rare species.
The gametangia develop acropetally and are situated dorsally along the stem between the leaf insertions.They are either intermingled or borne on separate shoots in monoicous species, or they may occur on separate plants in dioicous species.The antheridia are short-stalked, ± globose and either naked or shielded by perigonial bracts.The archegonia are exposed, but after fertilization the de veloping sporophyte becomes surrounded by a campanulate pseudoperianth, constricted at the sometimes stipitate base, and flaring at the plane, lobulate or crispate mouth.The globose capsule is raised on a moderately short or long seta, 6 or 7 to 10 cells in diameter; the capsule wall is bistratose, the outer wall with delicate, hyaline cells and the inner wall with irregularly quadrangular cells, contain ing nodular and semi-annular thickenings.The walls rup ture irregularly into small plates, releasing the spores and elaters.The spores are relatively large and highly ornamented with spines, lamellae or areolae.The ornamentation on the outer face is generally considered species-specific and re garded as essential for identification, although 'so variable that patterns of ornamentation . . .must be used to define taxa' (Schuster 1992).The elaters may be well or occasion ally poorly developed and are usually 2-or 3-spiral.The determination of sterile material is extremely difficult, if not impossible because of the plasticity of the gametophytes, the morphology of which varies considerably according to en vironmental conditions.

HISTORICAL NOTES
The genus Fossombronia has been relatively poorly studied in southern Africa.Lehmann (1829) described Fossombronia (sub Jungermannia) leucoxantha, collected by Ecklon on Table Mountain, Devil's Peak and Lion's Head and also reported the presence of F. (sub Junger mannia) pusilla L. on Table Mountain.Gottsche et al. (1844Gottsche et al. ( -1847) ) confirmed the presence of F. pusilla Nees and described F. crispa Nees from Promontorio Bonae Spei.Krauss (1846) reported F. angulosa 'in rupibus rivulor montium natalensium'.Mitten (1878) described F. tumida collected by the Rev. A.E. Eaton at the foot of Lion's Head and endorsed the records of F. crispa and F. leucoxantha from localities near Cape Town.Stephani (1900) described F. zeyheri andF. spinifolia. Sim (1926) added no new species, but Amell (1952) described three from the Cape: F. capensis, F. densilamellata and F. montaguensis (Perold 1997: 29).Amell (1963) stated that 'the South African species of the genus are in great need of revision'.Scott & Pike (1984, 1987a-c, 1988a, b), who studied the genus in Australia (i.e. the western parts of the State of Victoria and adjacent regions of South Aus tralia and New South Wales) for six years and described many new species from there, expected a comparable spe cies richness to emerge from a long-term study of the genus in South Africa (and South America), since they regarded its origins to have been m ainly in Gondwanaland.This paper is the first of a series dealing with southern African Fossombronia species.

METHODS
Samples of field-collected specimens were transferred to a conically shaped fine-mesh sieve and washed in a jet of running water to clear away soil particles.Remaining particles were manually removed by using fine-tipped for ceps.Cross sections were cut of some cleaned stems; several leaves and a pseudoperianth were detached and all trans ferred to a drop of water on a clean slide.Finally a coverslip was applied to the preparation, which was stored in a covered plastic dish lined with damp filter paper.During examination of the slide the evaporated water was periodically replen ished.The structures were measured and also photographed under a compound light microscope.
The remaining portion of the cleaned specimen was fixed in FAA (formaldehyde/alcohol/glacial acetic acid and distilled water in proportion of 2:1:1:20).For later reference some thalli were permanently preserved in FAA, the remainder only for several hours and then dehydrated in an ascending series of acetone to 100% and critical point dried in a Balzers Union dryer, using liquid CO2 as the transitional fluid.The thalli were mounted on alu minium stubs with double-sided Sellotape, gold-coated, then viewed and photographed, using an ISI SX 25 scan ning electron microscope (SEM).
There are some advantages to studying and photo graphing Fossombronia material, treated as described above, with the aid of SEM.Scott & Pike (1984) stated that the form, colour and orientation of the leaves (of dif ferent species) are distinct but 'beyond our powers to il lustrate and exceedingly difficult to describe'.Although the colour cannot be recorded by SEM, the form and cer tainly the orientation of the leaves can.Scott & Pike (1984) also observed that "male plants have often shriv elled and disappeared by the time the corresponding spores are ripe and the gametophyte is then so desiccated that its pristine vegetative appearance is irrecoverable'.Samples taken at different stages and treated as above, would have made comparisons easier for them.Scott & Pike did not illustrate the plants of any of their new spe cies, except F. rudis (Scott & Pike 1988b) and relied heav ily on d escriptions and the spore ornam entation to distinguish between species.
The spores and elaters were mounted on slides in Hoyer's fluid for examination and measurem ent by LM.For SEM m icroscopy some spores and elaters from the same capsule were allowed to air-dry, mounted on stubs with double-sided Sellotape, gold coated, viewed and p h o to g ra p h e d .SEM m icro g rap h s o f Fossombronia spores have frequently been published and have been used as an aid to identification.Features o f spore mor phology should be used with caution, however, because they can be rather variable, and the spores need to be fully mature.The Degree Reference System was used for recording distribution data (Edw ards & Leistner 1971).
Fossombronia gemmifera grows on sandy loam soil on stream banks or at seepages, often mixed with mosses or other Fossombronia species, particularly F. straussiana, which has hyaline rhizoids and is thus easily distinguished from it.This new species is quite distinctive with its highly convoluted pseudoperianth and by the frequent presence of dorsal gemmae for which it has been named.Its spore ornamentation with double-walled lamellae on the distal face and 'raised' on the proximal face above a clear marginal furrow, is also unique.There are two other species with purple rhizoids from the same distribution area: F. glenii which has spinous spores and F. zeyheri which has reticulate spores.Fossombronia gemmifera has been collected at several localities in Northern Province and Gauteng (Figure 4).
Fossombronia glenii grows on rather sandy soil in dry stream beds or on stream banks, or else on soil pockets in exposed rocky cliffs above streams.So far, it has only been collected at a few localities in Northern Province, Gauteng and Mpumalanga (Figure 4), but it is surely more widespread.It is easily recognized by the rather small pseudoperianth split into several lobes, by perigonial bracts with finger-like projections and by spinous spores.Because of its spinous spores, a specimen collected by Mogg (CH 157) at Wonderboom Poort, Pretoria, was previously misidentified as the so-called F. crispa, but the name had been misapplied (Perold b in press).Fossombronia glenii is dis tinguished from the winter rainfall species, F. leucoxantha, by the dentate leaves and pseudoperianths (Perold a in press).Both species have spinous spores.
This species is named in honour of an esteemed col league at the National Botanical Institute, Dr H.F. Glen, who has often collected liverworts, together with his wife, Mrs R. Glen (another colleague) and their young daughter, Melissa.
Fossombronia straussiana is often mixed with other Fossombronia species and grows on streambanks and in seepage areas at several localities in the Northern Province and Gauteng (Figure 4).More specimens of it, J. Braggins 91/191 and S.M. Perold 2654, were collected in 1991 in Malawi on the Zomba Plateau, as well as at Nyika Nat.Park, S.M. Perold 2663', thus it appears to be widespread . Vanden Berghen (1965) reported F. husnotii (with hyaline rhizoids) from the Congo Republic, Symoens 4329, and from Tanzania ( = Tanganyika), Bryan 1036.The spores of these specimens have much taller lamellae than those F. straussiana and also appear to differ from those of F. husnotii.In 1978 Vanden Berghen reported F. husnotii from Shaba, Zaire (Malaisse 9039), without mentioning the rhizoids, but presumably referred here because they are hyaline.Scott & Pike (1988a) comment that the spores of F. husnotii are extraordinarily variable and that more research is required.Beside F. husnotii, which has mostly hyaline rhizoids, Scott & Pike (1984) also described three new Australian species, F. punctata, F. scrobiculata and F. vermiculata, as having hyaline rhizoids on all or on most plants.
Fossombronia straussiana has been named in honour of Mrs Susan Strauss, owner of the Farm Geelhoutbosch, where she has collected it a number of times, together with other Fossombronia species.This species is easily distinguished by its hyaline or brownish rhizoids and dense, frilly leaves, its pseudope rianth with lamellate, lateral outgrowths, by the spore or namentation that usually has incomplete areolae with inclusions and by the usually finely papillose elaters.The specimen, Scott 13, has a larger and more elaborate pseudoperianth than those usually encountered in this spe cies.Its spore ornamentation is very similar, however, and the rhizoids are hyaline.