Two new species of Asteraceae from Northern and Western Cape , South Africa and a new synonym

We recognize two new species of Asteraceae from the winter rainfall belt of South Africa and reduce a third to synonomy. Senecio speciosissimus sp. nov. has been confused with S. coleophyllus Turcz. in the past but is distinguished by its taller stature, larger and more finely serrated leaves, and congested synflorescences containing (6 -) l 5 -40 flowerheads. The two species are also geographically separated: S. speciosissimus occurs in the Hottentots Holland and Franschhoek Mountains of the southwestern Cape, whereas 5. coleophyllus is endemic to the Riviersonderend Mountains. Chrysocoma hantamensis sp. nov. is a distinctive new species endemic to the Bokkeveld and Roggeveld Plateaus. It is distinguished by its resprouting habit. 3-5-fid leaves and large capitula, 12-15 mm in diameter, with lanceolate. 3-veined involucral bracts, the largest 9 1 0 x 2 mm. Investigation of the variation in leaf morphology of the two radiate species of Oncosiphon, O. africanum (PJ.Bergius) Kallersjo and O. glabratum (Thunb.) Kallersjo. reveals that only one species can be maintained, and O. glabratum is accordingly reduced to synonomy in O. africanum.


INTRODUCTION
During the preparation of the account of Asteraceae for Cape plants (Goldblatt & Manning 2000) it was evi dent that several undescribed species were represented among the collections at the Compton Herbarium.The more distinctive of these taxa were included in the treat ment of the relevant genera as numbered entries.Some of these species have since been described (Manning & Goldblatt 2002;Nordenstam 2003).One of the more dis tinctive of the unnamed species was Senecio sp. 3, w hich we describe here as 5. speciosissimus.In addition, an unusual species of Chrysocoma with pinnatisect leaves from the Bokkeveld and Roggeveld Escarpment in Northern Cape is described as the new species C. hanta mensis.At the same time we take the opportunity of reducing to synonomy the poorly understood species Oncosiphon glabratum.which further study reveals to be conspecific with O. africanum.
Distribution and ecology: Western Cape, restricted to the southwestern coastal mountains between 600 and 1 500 m, from Bainskloof in the north to Kogelberg in the south, a distance of ± 40 km (Figure 2).Plants grow in scattered communities, never very abundantly, in moist fynbos vegetation, in seepage areas or along streams.Rainfall in these mountains is relatively high, in parts averaging more than 2 500 mm per annum, falling predominantly during the winter months, although sum mer cloud condensing against the upper slopes provides some moisture through the summer.The single stemmed, willowy growth form indicates that the species is a reseeder, re-establishing after fire through the germi nation of dispersed seeds.Plants seem to be relatively short-lived and the species is apparently a member of early successional plant communities that do not persist into more mature fynbos older than 10 years.Flowering of the species begins in winter, in July, and continues into late spring and early summer, in November or December, with peak flowering between August and October.
Diagnosis and relationships: Senecio speciosis simus is a distinctive species.Plants are single stemmed, with erect, wand-like stems up to 1.8 m tall that are branched near the tops and densely leafy to wards the tips.The ovate to lanceolate, leathery leaves are usually cobwebbed beneath, and the flowerheads are clustered in paniculate synflorescences, with pink to mauve (rarely white) ray florets.In its habit, foliage and pink ray florets, it approaches Senecio coleophyllus Turcz.(Figure 3), a smaller species, 0.5-1.0m tall, of similar moist montane habitats in the Riviersonderend Mountains to the east, and the two are apparently geographic vicariants.S. speciosissimus is readily distinguished from S. coleophyllus by its taller stature, 0.9-1.8m tall, and congested, paniculate syn florescences comprising several, relatively short inflo rescences in the upper leaf axils of the flowering branches, producing an accumulated total of (6-) 15-40 flowerheads.S. coleophyllus, in contrast, produces a solitary, slender peduncle ± 100 mm long at each branch tip, bearing l-3 (-5 ) flowerheads.The leaves in that species are also smaller, 20-30 mm long vs 30-90 mm long, and proportionately more deeply and coarse ly incised. 5. glastifolius L.f., from moist mountain slopes between George and Humansdorp, is another tall, purple-flowered species that bears a superficial resem blance to S. coleophyllus and S. speciosissimus.It is readily distinguished from both by its thinner-textured leaves with the margins flat or only slightly revolute, the complete lack of indumentum on leaves and inflores cence, its diffuse synflorescence, and by the narrower, linear involucral bracts, at most 1.5 mm wide.
History: this striking species appears to have been first collected by the German botanist Rudolf Schlechter in the mountains above Franschhoek in November 1896.Several collections have been made since then, all of which have been referred to S. coleophyllus, and the plant has been illustrated under that name in various wild flower guides (Anonymous 1980;Burman & Bean 1985).This persistent confusion has obscured the true identity of the species.During the preparation of Cape plants (Goldblatt & Manning 2000), when we had the opportunity to examine recent collections of S. coleo phyllus from the Riviersonderend Mountains, it was clear to us that the plants from the Hottentots Holland Mountains represented a distinct species, and it was accordingly included in the account as Senecio sp. 3. The type of Senecio coleophyllus is from the Riviersonderend Mountains, as are all subsequent collections that match it.The recognition of the populations from the Hottentots Holland and adjacent mountains as a distinct species, S. speciosissimus, confirms that S. coleophyllus is endemic to the Riviersonderend Mountains, where it is found along the length of the range, from Jonaskop in the west to Pilaarkop in the east (Figure 2).

Senecio speciosissimus
2. Chrvsocoma L Chrysocoma L., a genus of 20 species, is endemic to southern Africa, mainly the drier western and southwest ern regions, with a single species extending into Mozambique (Bayer 1981;Herman et al. 2000).In the tribe Astereae the genus is distinguished by its shrubby habit and linear or oblanceolate leaves that are usually viscid, mostly entire and often ericoid, usually solitary capitula borne on elongate, naked peduncles, biseriate pappus with an outer series comprising a row of minute, persistent scales and an inner series of caducous bristles, and flattened cypselae with thickened margins contain ing apical resin sacs beneath the marginal ribs.All but two species have discoid capitula and just a single species, C. tridentata DC. is known to have some of the leaves toothed or lobed (Bayer 1981).The species de scribed here as G hantamensis is anomalous in Chrysocoma in its distinctly pinnatifid leaves and unusu ally large capitula but accords with the genus in other respects, particularly the fruit characters.

Distribution and ecology:
Northern Cape, known from two populations on the Bokkeveld and northern Roggeveld Escarpments (Figure 2).This region, known locally as the Hantam (Manning & Goldblatt 1997), is a significant cen tre of endemism (Van Wyk & Smith 2001).C. hantamen sis appears to be restricted to doleritic clays, growing in succulent karoo vegetation.The fine-grained, red dolerite soils of the Hantam support a wealth of edaphic endemic taxa adapted to their peculiar characteristics, including other recently described species of Asteraceae (Manning & Goldblatt 2001).C. hantamensis bears a remarkable super ficial resemblance to another distinctive, narrow endemic of this region, Euryops mirus B.Nord.The two species, which grow together at the type locality east of Nieu woudtville, are extraordinarily similar in vegetative form, sharing short, partially subterranean stems and branches bearing pinnatifid leaves, and producing annual flowering shoots with long, naked peduncles bearing solitary flowerheads.It would appear to be a marked instance of ecologi cal convergence.
Diagnosis and relationships: the highly distinctive C. hantamensis is readily separated from all other species of Chrysocoma by its 3-5-fid leaves and large capitula, 12-15 mm diam.with lanceolate, 3-veined involucral bracts, the largest 9-10 x 2 mm.In its distinctly lobed leaves it approaches C. tridentata DC. (including C. pinnatifida DC.) (Bayer 1981) but this species from the Little Karoo is a divaricately branched shrublet with rather fleshy, mostly subterete leaves, and with short peduncles at most 30 mm long, bearing capitula 10-12 mm diam.In addition, the involucral bracts, like those of all other species of Chrysocoma, are smaller, ± 5 x 1.0-1.5 mm, linear-lanceolate and 1-veined.C. hanta mensis is probably most closely allied to C. oblongifolia DC., which extends from Namaqualand through the Hantam and into the Tanqua Karoo.Both species are subshrubs with decumbent annual stems bearing rela tively broad leaves with strigose margins and large capi tula carried on long peduncles.The decussate lower leaves of C. hantamensis and C. oblongifolia are also evident in the few other species of Chrysocoma that are subshrubs rather than true shrubs, although their opposite arrangement is easily overlooked.C. oblongifolia differs from C. hantamensis in its entire, oblanceolate leaves, glandular-hairy rather than villous stems and peduncles, slightly smaller capitula, 10-12 mm diam., and smaller, 1-veined involucral bracts.
History: this unusual species was brought to our atten tion by Simon Todd, who collected it as part of his vege tation studies in the Nieuwoudtville area.Subsequent investigation brought to light an earlier collection from the northern Roggeveld Escarpment, made by M.F.Thompson in 1975, at which time it was filed among the undetermined species of Chrysocoma.The specimen was apparently overlooked by Bayer (1981) in her revision of the genus.

Oncosiphon Kallersjo
The genus Oncosiphon Kallersjo (Anthemidae: Matricariinae) (Kallersjo 1988) was established for a small group of annual species from Western and Northern Cape jV9 h o $07. 3 o ' ; te'bo that had been previously placed either in Matricaria (Harvey 1865), or segregated between the genera Pentzia (discoid species) and Matricaria (radiate species) (Hutchinson 1917).As circumscribed by Kallersjo   (1988), Oncosiphon is defined by its annual habit, 4lobed corolla with a brittle, swollen tube, and 4-ribbed cypselae that lack myxogenic hairs and bear a small, unequal-sided pappus.Seven species are currently recog nized in the genus (Kallersjo 1988), just two of them with radiate capitula.These two species, O. africanum (P.J.Bergius) Kallersjo and O. glabratum (Thunb.)Kallersjo, are endemic to the coastal lowlands of the southwestern Cape (Goldblatt & Manning 2000), from near Leipoldtville to Cape Town.They occur along the margins of seasonal, often somewhat saline pans, and flower in late spring as the pans dry out.The two species were retained as distinct by Kallersjo (1988)    plants (Figure 5).Well-grown, branched specimens typi cally have larger, more highly dissected leaves than smaller, unbranched specimens.For instance, Compton 9815 (NBG) comprises a dozen depauperate plants, most of which bear simple, pinnatisect leaves (Figure 5A) but one of which has the lower leaves weakly bipinnatisect (Figure 5B).While most of the leaves of Compton 5086 (NBG) are bipinnatisect (Figure 5C), the lower leaves of different branches on the well-grown plants that comprise Compton 15129 (NBG) and Hugo 667 (NBG) display a range of degrees of dissection, from simply pinnatisect to strongly bipinnatisect (Figure 5D-F).The leaves in all other species of Oncosiphon are bipinnatisect (rarely tripinnatisect) (Goldblatt & Manning 2000).Examination of the type of O. glabratum, which comprises unbranched plants, reveals that one of the leaves displays a secondary lobe and is therefore by definition bipinnatisect.The dis tinction between the two taxa is clearly untenable and O. glabratum is accordingly reduced to a synonym of O. africanum.
(1865), actually has distinctly bipinnatisect leaves and thus falls within the circumscription of O. africanum.In contrast, the ample material determined as O. africanum displays a range of leaf forms that suggests that the degree of dissection is often associated with the luxuriance of the