Studies in the Marchantiales ( Hepaticae ) from southern Africa . 3 . The genus Targionia and T . hypophylla with notes on T lorbeeriana and Cyathodium foetidissimum ( Targioniaceae )

A taxonomic account of the genus, Targionia. and its only representative in southern Africa, the almost cosmopolitan T. hypophylla, is given here. Much more southern African and other material, than was available to the previous authors. Sim (1926) and Amell (1963) has been examined. Material collected at Knysna by Duthie was identified by Amell (1963) as Cyathodium foetidissimum. but is shown to have been misidentified and is actually a specimen of Riccia rubricollis. The presence of the genus, Cyathodium in southern Africa, has not been confirmed.

Thallus, medium-sized, fleshy, lobes linear, sometimes widening toward apex or cordate, somewhat leathery, light green to darker green, often with a waxy bloom, in crowded patches or extensive sheets; on soil in sheltered rocky clefts or a pioneer on disturbed soil.
Branches often simple, sometimes repeatedly furcate or only apically branched, or with ventral innovations; thickened over midrib, rather abruptly thinning into wings; apex notched, tips of scale appendages curving backwards over it; not grooved.Dorsal epidermis hyaline, cell walls thickened, especially at corners; air pores simple, conspic uous, slightly raised, with 3 concentric rings of cells, their walls thin, leading below into shallow air chambers con taining chlorophyllose filaments; oil cells present; storage tissue 3-5 times thicker than assimilation tissue above; ventrally purple-black; some rhizoids smooth, others pegged.Scales in one row on each side of midrib, dark purple, large, obliquely triangular with broadly 'awfshaped appendage.

DISCUSSION
In the family Targioniaceae, two subfamilies, Targionioideae and Cyathodioideae Grolle, are recognized, each with only a single genus.They are characterized by gynoecia that become ventrally displaced at the apex of the thallus and capsules which are enclosed in a bivalved.mussel-shaped involucre.
In Targionia species the thalli are compact and some what leather), with low air chambers containing chlorophyllose filaments and a thick layer of storage tissue below : in Cyathodium species the thalli are delicate, with tall air chambers lacking chlorophyllose filaments and with much reduced storage tissue.
To date, no monographic studies have been done on the genus Targionia.although as many as 26 names have been recorded under it (Geissler & Bischler 1990).Piippo (1991), however, recently speculated that most of these names will undoubtedly prove to be synonyms of T. hypophylla.There are at least two other Targionia species with well-defined specific limits, namely T. stellaris (K.Miill.)Hassel de Menendez (1963) from Argentina and a new species from India reported by Udar & Gupta (1983).
Targionia hypophylla.the only representative of the genus, is a widespread, almost cosmopolitan species [for total range see Piippo (1991)].occurring especially in tem perate and seasonally dry areas w here it grows as a xero- phyte on soil in rock crevices, on soil over rock outcrops or under rock overhangs, or as a pioneer on disturbed earth banks, like road cuttings.Sometimes other liverworts such as Riccia spp., Plagiochasma spp., or Mannia spp.are also present.
Targionia hypophylla is easily recognised, when fertile, by the ventrally displaced capsule contained in a shiny black pouch at the apex, by which further lengthening of the branches is arrested.Sterile plants are distinguished by their dark green, somewhat leathery appearance, the conspicuous white-encircled air pores and reddish to pur ple-black triangular ventral scales with a single append age.Kashyap (1914) regards it as a very variable species, and so does Schuster (1992), who thinks that incipient speciation is under way; on the other hand Muller (1951Muller ( -1958) ) observes that, in spite of its wide distribution, plants display little variation and the species is probably very old.It is somewhat similar to Mannia spp., but these differ from it by their less conspicuous air pores and by capsules borne aloft on a longish stalk.Plagiochasma spp.have smaller air pores and more pronounced spicules on the dorsal epidermal cells, with the capsules also raised on a stalk.
T. hypophylla was previously described from southern Africa by Sim (1926) andAmell (1963).It has been quite rarely collected in Namibia (from whence Volk (1979) recorded 14 collections), central Transvaal, Natal, Orange Free State, Lesotho, Transkei, central, southern and eastern Cape, but frequently in the winter rainfall areas of the northwestern and southwestern Cape (Figure 4).
Further north in Africa it has also been recorded from Ghana by Jones & Harrington (1983), Tanzania (Bizot et al. 1978), Kenya and again Tanzania (Bizot et al. 1985), Malawi (S.M. Perold 2665 PRE), Zambia (Vanden Berghen 1972), Zimbabwe (Sim 1926;Best 1990) and the adjacent islands of Madagascar (Arnell 1963) and Reunion (Bischler 1990), although in the latter report, it is listed as T. hypophylla and in brackets, 'or T. lor-beeriana\ Frey & Kiirschner (1988) report T. hypophylla from the Arabian Peninsula (together with T. lorbeeriana) as well as a possible new morphotype, T. hypophylla spp.linealis (spp.nova?).T. elongata is also known from Af rica (Ethiopia), and Scott & Pike (1988) have published SEM micrographs of its spores, which are very distinct and clearly different from those of T. hypophylla, in that there are only 5 or 6 large, ± smooth areas on the distal face, as opposed to the usual 16 or 17 reticulated ones in T. hypophylla.On a recent visit to Malawi, some speci mens of Targionia were collected, one of which, S.M. Per old 2653, had up to 30 reticulated areas (Figure 3F), 7.5-10.0(im wide, on the distal face; the spore diameters were 65-72 |im.It is not certain, however, whether we are dealing with a different species or not.Targionia hypophylla L. var.fimbriata K. Muller is not treated as a distinct variety in this study of southern Af rican specimens as was done by Amell (1963), because the presence of fimbria along the ventral scale margins is very variable, even in thalli from the same population.Apical scales are also more frequently fimbriate than older ventral scales on the same branch.Schuster (1992) regards the intrapopulational variation in this feature as so great that no taxonomic segregation of the two extremes seems possible to him.1956; Jovet-Ast &Zigliara 1967 andZigliara 1970) have confirmed the existence of an allied species, T. lorbeeriana (Muller 1940) of which I have studied the type specimen (leg.Huber-Tharandl, (5) collected in Sicily).Arnell (1963) and Magill & Schelpe (1979) record the presence of T. lorbeeriana in southern Africa, but this could not be confirmed in the present investigation although (Arnell (1963) even records T. lorbeeriana var.fitnbriata from here).The specimens which Arnell placed under T. lorbeeriana, Garside 6573 [spore diameter 57.5-62.5 |im (Figure 2E)] and Schelpe 4947 [spore diameter 75-85 (im (Figure 2F)] are undoubtedly T. hypophylla, judging by their spore ornamentation and cell measurements of the thalli and scales.The correct naming of old dried herbar ium material is, however, difficult, since the colour of the thalli fades, as does the distinctive odour of T. lorbeeriana.Spore ornamentation (see later) seems to be a more reli able and certainly more permanent distinguishing charac ter.Grolle (1983) regards reports of the occurrence of T. lorbeeriana in the East African Chyulu Mountains (Bizot et al. 1978), as well as in the Cape (and India), as needing verification.Targionia lorbeeriana is thought to be a 'triploid race' of T. hypophylla, as it has 27 chromosomes.It is said to be characterized by a strong smell of acid pear drops when fresh; by the cordate shape and light green colour of the thallus; by larger, oval air pores and by dif ferent cell dimensions [for the latter see Zamora et al. (1990)1.Schier (1974) reports slight differences in the flavonoids of the two species.Differences in the spore ornamentation of the two species were demonstrated by Jovet-Ast & Zigliara (1967).Scott & Pike (1988) consider the spore sculpturing as the clearest and least ambiguous way of separating the two species: in their Australian ma terial they consistently found that T. hypophylla has reg ular areolae, whereas in T. lorbeeriana the areolae are irregular in arrangement.
Spore samples of 20 different specimens of T. lorbeeri ana (on loan from European herbaria) were presently stud ied with the SEM and compared with more than 40 spore samples of local T. hypophylla.In T. lorbeeriana spores there are fewer ridges on the proximal face (Figure 3E) and on the distal face, the fine reticulum, particularly that covering the inside of the polygonal areas of the coarse reticulum, has thicker walls (Figure 3A-D); the proximal spore face in T. hypophylla has numerous contorted ridges and the walls on the distal face are thin and the areolae oval or irregular in shape and size, the fine mesh present ing an altogether 'looser' appearance (Figure 2A, D-F).Of the southern African material examined, spore orna mentation of Magill 6606, Van Rooy 2973, 3142a  Pike (1988: plate 1.1), appear to be of T. lorbeeriana and 1.2 of T. hypophylla, in other words, the reverse of what they are stated to be.The T. hypophylla spores illustrated by Taylor et al. (1974) are closely similar to those in my study.

Cyathodium foetidissimum Schiffner
Amell (1963) observed that a specimen in the National Herbarium.Pretoria, collected by A.V. Duthie at Belve dere, Knysna, probably belongs to this species, i.e.Cyathodium foetidissimum.This specimen has been ex amined and its spores photographed.It is undoubtedly a species of Riccia and the ornamentation of the spores proves it to be R. rubricollis Garside & Duthie ex Perold (Perold 1991).On the small specimen packet inside the larger envelope, in Sim's handwriting is the note 'Miss Duthie's (No. 23) new Riccia, Belvedere, Aug. 1928* and below it, in Amell's writing and signed by him is the annotation 'Cyathodium sp.'.One wonders why Amell had ignored Sim's identification, as the latter must have received the specimen from Duthie herself.In mitigation, it may be added though, that the material had been pressed and it is only a small sample, perhaps even a little atypical, but the internal sporangia and spores immediately place it correctly.
The other two species of Cyathodium.C. africanum and C. aureonitens which Amell (1963) thought would possibly be found in southern Africa, have so far not been collected here and it is doubtful if they ever will be, since they are conspicuous and luminous green, and it is un likely that they could have been overlooked.The presence of the genus, Cyathodium in southern Africa has therefore not been confirmed although it is very widely distributed in the rest of Africa (Jones 1952).

FIGURE 1 .
FIGURE 1.-Targionia hypophylla, A, dorsal aspect of thallus with tip of involucre protruding at apex; B, thallus with short ventrally innovating branch bearing terminal disc with antheridia; C, ventral aspect of thallus with pouch-like involucre at apex and 2 rows of ventral scales; D, tranverse section of thallus; E, air pore from above; F, transverse section of air pore, dorsal cells and chlorophyllose filaments; G, scale with margins ± intact; H, scale with fimbriate appendage; I, cells of capsule wall with thickening bands.A, C, D, F, I, Koekemoer 477a; B, E, G, Garside 6674; H, Schelpe 4947.A, B, C, x 11; D, x 22; E, x 300; F, x 275; G, H, x 55; I, x 250.

FIGURE 1 .-
FIGURE 1.-Targionia hypophylla, A, dorsal aspect of thallus with tip of involucre protruding at apex; B, thallus with short ventrally innovating branch bearing terminal disc with antheridia; C, ventral aspect of thallus with pouch-like involucre at apex and 2 rows of ventral scales; D, tranverse section of thallus; E, air pore from above; F, transverse section of air pore, dorsal cells and chlorophyllose filaments; G, scale with margins ± intact; H, scale with fimbriate appendage; I, cells of capsule wall with thickening bands.A, C, D, F, I, Koekemoer 477a\ B, E, G, Garside 6674; H, Schelpe 4947.A, B, C, x 11; D, x 22; E, x 300; F, x 275; G, H, x 55; I, x 250.