Three new species and some nomenclatural changes in Senecio (Compositae/Asteraceae: Senecioneae) in the Flora Zambesiaca area

Three new Senecio species are described, S. fanshawei from Zambia, S. ngandae from Malawi and S. nyangani from Zimbabwe. A new combination is made under S. brachypodus and a taxon is added to the synonymy of this species; single taxa are added for the first time to the synonymy of S. coronatus and S. purpureus, and two taxa each are added for the first time to the synonymy of S. hochstetteri and S. triactinus.


Introduction
During a revision for the Flora Zambesiaca account of the genus Senecio L., I encountered specimens that did not fit in any of the existing taxa and were different enough to warrant description as new species; these are described below. Several other taxa were found to be so close to each other that merging seemed warranted.
The taxon known as Senecio pleistocephalus S.Moore differs from S. brachypodus DC. only in its discoid (as opposed to radiate) heads, a difference already remarked on by Hilliard in her classic study of the Compositae of Natal . The ranges of these two taxa partly overlap, and I am changing the status into a variety of S. brachypodus. Senecio callimocephalus S.Moore is brought into the synonymy of this new variety, as there are no differences between these two taxa.
An old name, Othonna plantaginea Hiern, is resolved into the synonymy of Senecio coronatus (Thunb.) Harv., as there are no differences between the two.
The names of two taxa are moved into the synonymy of the widespread and variable Senecio hochstetteri A.Rich.; that of another taxon is moved into the synonymy of the widespread S. latifolius DC., another one into the synonymy of S. purpureus L., and two more into the synonymy of S. triactinus S.Moore.
RECOGNITION. This species seems closest to Senecio propior S.Moore but differs in the lack of a woolly root-crown, the glabrous leaves, the slightly longer phyllaries with hairy (rather than papillate) apex, the slightly longer disc florets and the glabrous achenes. DISTRIBUTION With only a single specimen known, occurring in a habitat that is declining as it is being used increasingly for agriculture, this must be a species in danger; however, as it might have been confused with more common taxa, I prefer to keep this as Data Deficient [DD], until specific searches for the taxon (as well as research into the status of the habitat in this area) have provided more data. http://www.ipni.org/urn:lsid:ipni.org:names:77202824-1 Erect herb 40 -90 cm high with basal leaves and fewer cauline leaves; stems unbranched except for inflorescence, glabrous except for inflorescence axes. Basal leaves narrowly elliptic, 20 -35 × 1 -2.7 cm, base long-attenuate, margins dentate, apex attenuate; glabrous except for some minute hairs on midrib and margins; cauline leaves similar but smaller, and more distal ones with cuneate base. Capitula discoid, 4 -13 together in erect sub-corymbose panicles, inflorescence axes slightly hairy and with small bracts; stalks of individual heads 1 -7.5 cm long; involucre campanulate; calycular bracts several, linear and to 5 mm long; phyllaries 20 -23, 5.3 -5.5 mm long, the outer with reddish entire margin, the inner with broad translucent margin, sparsely hairy at base with crinkly multicellular hairs, and with little tuft at apex, darker at apex. Florets 34 -38, corollas maroon or crimson-brown, 4.5 − 6 mm long, papillate at lobe apices; basal node glabrous, slightly tuberculate; style arms 0.9 − 1 mm long, truncate with a ring of papillae at apex. Achenes 1.2 − 2.6 mm long, slightly 10-ribbed, glabrous; pappus of many fine white barbellate setae, 4.5 -6 mm long. Fig. 2.
RECOGNITION. This species differs from all others with mauve or reddish florets in the absence of ray florets, the glabrous stem and leaves, the leaf shape, number and size of phyllaries, and the glabrous achenes. HABITAT. Grassland; alt. 2200 -2400 m a.s.l. CONSERVATION ASSESSMENT. This taxon has an EOO of less than 1 km 2 and an AOO of 4 km 2 . As a strict and narrow endemic to the Nyika National Park, this is a clear example of Least Concern (Conservation Dependent) [LC(CD)], as it occurs in a well-protected area; any negative change in the status of the protected area would very quickly change the assessment. NOTE. Relationships are possibly with Senecio purpureus and S. erubescens, but S. ngandae differs quite substantially from these two taxa.
RECOGNITION. This species most resembles Senecio moorei R.E.Fr. from Uganda and Kenya but differs in the glabrous stem and leaves (not tomentose and sometimes glandular), narrower leaves with thickened revolute margins (not denticulate to dentate) and eight (not 11 -13) ray florets with wider rays.  . Although the type specimen in P has a label saying 'isotype', this must have been part of Schultz Bipontinus' own herbarium. Therefore, I regard this sheet, which bears notes in ms, as the holotype).   Shrubby scrambler with long branches, 2 -5 m high; stems fleshy, more than 5 mm across, whitish green, glabrous. Leaves semi-succulent, elliptic to obovate, 1.5 -7 × 0.7 -3.7 cm, base attenuate, margin almost entire to slightly lobed with several, up to 7 mm long, narrow lobes near leaf base, apex acute to obtuse, glabrous. Inflorescences of dense corymbs or corymbosepaniculate, the whole to 18 × 16 cm. Capitula homogamous, dark yellow with strong unpleasant smell; calycular bracts few, up to 1.5 mm long; phyllaries 5 -7 (in specimens examined), 3 -4 mm long, with thin membranous margins, glabrous; disc florets 8 -13, presumably yellow, narrowly infundibuliform, 4.4 -6 mm long. Achenes 1.2 -1.5 mm long, glabrous; pappus 4 -6 mm long. HABITAT. Occurs in thicket margins, woodland and disturbed areas, sometimes covering shrubs and small trees; alt. 0c. 1100 m a.s.l. NOTES. I take Burtt Davy 2906 to be the holotype, as this is the main sheet cited by Moore (1905). He further mentions "(Alsoat Kew -Delagoa Bay; Monteiro, 25)" and I take this to be an indication to regard Monteiro 25 as a secondary citing. I agree with Hilliard that this is distinct from Senecio brachypodus only by its discoid heads, always with five phyllaries (as opposed to radiate with 5 -8 phyllaries). Hilliard reports that its range partly overlaps with the range of S. brachypodus s.s. and, that in Umgeni Valley, Kwazulu-Natal, the two taxa grow together and flower at the same time; Hilliard felt it was possible that subspecific rank might be more appropriate. I agree with her as to the need to show that these taxa are closely related, and the taxon is brought into varietal rank here, rather than subspecific, as the ranges overlap. Variety pleistocephalus is discoid, not 'disciform' as stated by Moore. Hilliard (1977)  TUB00 5654]) which seems to differ from S. hochstetteri in shorter, stalked glands on the leaves (rather than twisty glandular hairs) and in the inflorescence, which in the type has either solitary or paired heads. Much of the South African material at Kew named S. variabilis has longer leaf indumentum and more heads per stem but almost uniformly is described as having purple or mauve florets. The protologue of S. variabilis specifically declares that the florets are golden yellow (Capitulis dicoideis, 25 − 28 floris, aureis), although the author compares his new taxon to both S. mucronulatus (now a synonym of S. purpureus, with purple or mauve florets) and S. hochstetteri (published years later, but known to Schultz Bipontinus). With limited time on my current project I am leaving the taxa separate.
I have put Senecio acroleucus into synonymy here. This taxon was described by Merxmüller based on a single specimen, Dehn 240 from Marondera (Zimbabwe), but he only compared it to S. effusus (a synonym of Crassocephalum uvens). This specimen is really indistinguishable from the range of S. hochstetteri.
I have also reduced Senecio greenwayi to synonymy. The differences between that taxon and S. hochstetteri were gradual, with the capitula at the larger end of the range, but the key differences all disappear into a continuous range of variation in the specimens I have seen.