Thymelaeaceae are well represented in southern
Africa, with ± 190 species in nine genera (Bredenkamp
& Beyers 2000; Beaumont et al. 2009). Preliminary
phylogenetic analyses of nuclear and plastid DNA
sequences (Van der Bank et al. 2002; Beaumont et al.
2009) indicate the need for substantial revision in the
generic circumscriptions in subfamily Thymelaeoideae.Web of Scienc

Boatwright, James S.

Manning, John C.

Bothalia

University of the Western Cape Research Repository

84  Bothalia 43,1 (2013)THYMELAEACEAELASIOSIPHON RIGIDUS, A NEW SPECIES FROM THE TANKWA KAROO AND TWO NEW COMBINATIONS IN THE GENUS FOR SOUTH AFRICAThymelaeaceae are well represented in southern Africa, with ± 190 species in nine genera (Bredenkamp & Beyers 2000; Beaumont et al. 2009). Preliminary phylogenetic analyses of nuclear and plastid DNA sequences (Van der Bank et al. 2002; Beaumont et al. 2009) indicate the need for substantial revision in the generic circumscriptions in subfamily Thymelaeoi-deae. This is especially evident in the large and diverse Bothalia 43,1 (2013)  85 genus Gnidia L., with > 140 spp. in tropical and south-ern Africa and Madagascar. Gnidia is evidently highly polyphyletic as currently circumscribed and is re-presented by at least four distinct lineages scattered throughout the Thymelaeoideae. As a fi rst step towards a monophyletic generic classifi cation of the subfamily, Beaumont et al. (2009) reinstated the genus Lasiosi-phon Fresen., originally distinguished from Gnidia and allied tetramerous genera by its pentamerous fl owers but subsequently included within Gnidia by Petersen (1959, 1978) on account of the evident instability of this character. Molecular analyses retrieved a monophyletic Lasiosiphon clade (comprising all pentamerous species of Gnidia sensu lato plus some tetramerous species) that was separated from the remaining Gnidia species by a well-supported clade comprising the genera Dirca L., Ovidia Raf., Peddiea Harv. and Stephanodaphne Baill. (Beaumont et al. 2009). Secondary characters diagnos-tic for Lasiosiphon are the capitate, involucrate infl ores-cences subtended by foliaceous or petaloid bracts, the pubescent hypanthium, and the waxy, bright yellow to orange or red hypanthium lobes. With the inclusion of tetramerous species, the genus is diagnosable only by a combination of characters. Like Gnidia, it also includes some species with ebracteate, few-fl owered infl ores-cences plus taxa with and without petaloid scales in the mouth of the hypanthium (Beaumont et al. 2009). Lasi-osiphon currently numbers some 35 spp. from Africa and Madagascar, with ± 20 recorded from southern Africa (Wright 1915).Here we describe a distinctive new species of Lasi-osiphon endemic to the Tankwa [Tanqua] Karoo, previ-ously misidentifi ed and illustrated as Gnidia microphylla Meisn. (Van der Merwe 2010). It is distinguished by its rigid, divaricately branched habit, small, glabrous leaves, capitate infl orescences with bright yellow and reddish petaloid involucral bracts, and fl owers lacking petaloid scales (Figure 1). The specifi c epithet alludes to its characteristic habit. The species appears to have been fi rst collected by J.P.H. Acocks in 1956, and has been consistently misidentifi ed as G. microphylla (now L. microphyllum) since then.We consulted the collections in BOL, NBG, PRE and SAM (acronyms after Holmgren et al. 1990) as these contain the most extensive holdings of the southern Afri-can winter rainfall fl ora, and studied the species in the fi eld. We also take this opportunity to provide new com-binations for Gnidia pedunculata Beyers and G. seri-cocephala (Meisn.) Gilg. ex Engl., which accord with Lasiosiphon in all critical morphological characters but lack combinations in this genus. Lasiosiphon rigidus J.C.Manning & Boatwr., sp. nov. Resembling Lasiosiphon microphyllus (Meisn.) Meisn. and L. polycephalus (C.A.M.Mey.) H.Pearson in the involucrate fl ower heads surrounded by petaloid bracts, but differing in the rigid, divaricately branched habit and fi ve caducous involucral bracts, which are api-culate, yellow fl ushed with dark red and subglabrous or shortly sericeous with straight hairs; L. microphyllus has ascending branches, 5–8, obtuse, persistent involucral bracts, which are yellow to green and densely pubescent with crisped hairs; L. polycephalus has a virgate habit and 3–6, obtuse, persistent involucral bracts, which are yellow or reddish brown and densely sericeous with broad, hairless margins.TYPE.—South Africa, Northern Cape, 3219 (Wup-pertal): Tankwa [Tanqua] Karoo National Park, SW foot of Leeuberg, along drainage lines, (–BB), 20 June 2012, Manning 3363 (NBG, holo.; K, MO, PRE, iso.).Rigid, densely divaricately branched shrublet up to 0.6(–1.0) m high, branches suberect to spreading, sparsely leafy and glaucous when young but later devel-oping grey, fi ssured bark. Leaves alternate, suberect or ± spreading, rather distant, shortly petiolate, blade obovate to oblanceolate, 5–10(–12) × (1.5–)2.0–4.0 mm, obtuse to acute, plane or shallowly concave, leathery, glaucous, midrib weakly raised beneath, petiole 0.2–0.5 mm long. Infl orescence terminal on main and lateral branches, capitate, bracteate, ± 15–30-fl owered, branches becom-ing hard and thorny with age; involucral bracts 5, ovate, 10–11 × 5–6 mm, yellow ± fl ushed wine-red or entirely maroon, papery, faintly nervate, apiculate, subglabrous to densely sericeous, caducous and mostly fallen at fl owering. Flowers chrome-yellow with maroon tube, unscented during day but strongly lilac-scented at night; pedicel ± 1 mm long, densely appressed pubescent; hypanthium 13–18 mm long, circumscissile 4.5–6.0 mm from base, basal portion narrowly ovoid, densely sericeous with long, ascending, silvery to golden hairs 2–5 mm long, upper portion tubular but infl ated and subglobular in distal 1.5 mm, densely appressed pubes-cent with straight, sericeous hairs ± 1 mm long in lower portion but becoming villous with crisped hairs distally, especially on distal swelling; sepals 5, spreading, ovate, 4–5 × 2.0–2.5 mm, glabrous and waxy above but villous beneath, margins revolute and apex refl exed, thus appar-ently oblong-emarginate and ± 1.5 mm wide. Petaloid scales 0. Stamens 4 + 4, subsessile; outer whorl inserted 0.5 mm below rim of hypanthium, half-exserted; inner whorl inserted at base of bulge ± 1.5 mm within throat of hypanthium, fully included; anthers ± 1 mm long at anthesis. Ovary ellipsoid and attenuate basally, ± 2 mm long, sparsely sericeous; style inserted laterally, included and reaching less than halfway up hypanthium, ± 4.5 mm long, stigma penicillate. Fruit not seen. Flowering time: June–Sept. Figures 1, 2.Distribution and ecology: evidently endemic to the central and eastern parts of the Tankwa Karoo, an arid basin between the Cedarberg and Roggeveld Mtns (Figure 3); the species is best known from around the Elandsberg, especially along the SW foot of the Leeu-berg. It is restricted to loamy soils on the banks and mar-gins of seasonal washes and drainage lines and is never abundant. Plants are typically found growing through other, often strongly thorny or prickly shrubs.Lasiosiphon rigidus is one of several shrubby species marking seasonal drainages in the Tankwa, others being Osteospermum sinuatum (DC.) Norl., Berkheya spinosa (L.f.) Druce, Eriocephalus microphyllus DC. and Pte-ronia villosa L.f. (all Asteraceae), Aridaria noctifl ora (L.) Schwantes (Aizoaceae), and Melolobium candicans (E.Mey.) Eckl. & Zeyh. (Fabaceae). 86  Bothalia 43,1 (2013)Diagnosis and relationships: although initially con-fused with Lasiosiphon microphyllus, a microphyllous subshrub from drier interior South Africa with similar involucrate fl ower heads surrounded by petaloid bracts, L. rigidus is distinguished by its very different growth form and by the shape and vestiture of the involucre. L. microphyllus is a low-growing subshrub producing slen-der ascending stems with ± appressed leaves, and virgate fl owering branches 0.5–0.8 mm in diameter and leafy to the tips, with the uppermost leaves grading into 5–8 involucral bracts. The bracts persist through the fl ower-ing period and are obtuse and densely pubescent with crisped hairs. From herbarium specimens they appear to be pale yellow or greenish in colour. L. rigidus is a rigid, divaricately branched shrub with suberect or ± spread-ing leaves and short fl owering branches 1.0–1.5 mm in diameter, with the uppermost leaves distant and well dif-ferentiated from the strictly fi ve involucral bracts. These are apiculate and subglabrous or shortly sericeous with straight hairs. The yellow bracts are almost completely fl ushed with dark wine red and are caducous, abscising soon after anthesis so that the fl owers are left exposed. Although L. microphyllus is described as having small petaloid glands (Wright 1915), all the specimens that we have examined lack these glands.Lasiosiphon rigidus is evidently also allied to L. polycephalus (C.A.Mey.) H.Pearson, a virgate subshrub widespread through the drier parts of the subregion, with similar scanty foliage and fl owers in heads surrounded by yellow to reddish brown petaloid involucral bracts and lacking petaloid scales. It is recognised by its wiry, well-branched stems with sharply ascending branches and numerous, small fl ower heads with less than ten fl owers, subtended by densely sericeous bracts that are characterised by their broad, hairless margins. These three species all share densely sericeous fruits with very long hairs and appear to comprise a group of closely allied taxa from the arid South African interior. Additional specimens seenNORTHERN CAPE.—3119 (Calvinia): Klipbank, SW of Calvinia on lower N slopes, (–DD), 23 July 1956, Acocks 18870 (PRE). 3219 (Wuppertal): Tankwa Karoo National Park, Biesiesfontein, (–BB), 22 July 2006, Manning 3014 (NBG); Tankwa Karoo National Park, foot of Leeuberg, (–BB), 3 Aug. 2006, Sachse 48 (PRE); Tankwa Karoo National Park, N end of Leeuberg, E of Varsfontein, (–BB), 16 Aug. 2007, Helme 4710 (NBG); Doornrivierkruising met Ceres, Sutherland pad, (–BC), 9 Jul. 1991, Van Zyl 4198 (NBG); Tankwa Karoo National Park, Grasberg South 1103, (–BC), 16 Aug. 2008, Steyn 1446 (PRE); Tankwa Karoo National Park, track to Volmoersfontein, S of Potkleib-erg, (–BD), 6 Aug. 2009, Steyn 1525 (PRE); Tankwa Karoo National Park, track between Luiperdskop and Varsfontein, (–BD), 15 Aug. 2011, Steyn 1862 (PRE). 3220 (Sutherland): Tankwa Karoo National Park, Farm Leeukloof 114, slope W of Leeukloof, (–AC), Sept. 2007, Sachse 618 (PRE).WESTERN CAPE.—3219 (Wuppertal): Farm Koffi ewater, (–BC), 4 Aug. 2007, Bester 7722 (PRE); 3220 (Sutherland): Tankwa Karoo National Park, near Paulshoek, (–AC), 27 Aug. 2004, Steyn 624 (PRE); Bantamsfontein Kop (–CC), 17 June 1965, Acocks 23667 (PRE).Imprecise locality: Ceres Karoo, 13 May 1946, Nel s.n. STE26832 (NBG, 3 sheets).New combinationsWith the reinstatement of the genus Lasiosiphon by Beaumont et al. (2009), it is necessary to provide combi-FIGURE 1.—Morphology and habit of Lasiosiphon rigidus. A–C, E, infl orescences with fl owers at various stages; D, rigid, divaricately branched shrubby habit. Photographs: John Manning.Bothalia 43,1 (2013)  87 FIGURE 2.—Lasiosiphon rigidus, Manning 3363. A, fl owering branch; B, leaf and leaf T/S; C, involucral bract; D, bud; E, fl ower; F, open fl ower with detail of androecium; G, gynoecium. Scale bar: A, 10 mm; B–G, 2 mm. Artist: John Manning.FGACBDE88  Bothalia 43,1 (2013)nations for the following two species. Gnidia pedunculata is a narrow endemic of the Knersvlakte resembling the group of three species of Lasiosiphon discussed above in its glabrous stems and leaves and ± capitate infl orescences with petaloid involucral bracts and waxy, golden yellow fl owers with a pubescent hypanthium. It differs from them in its tetramerous fl owers with small petaloid scales. Gnidia sericocephala was one of 11 species treated by Wright (1915) in the genus Arthrosolen C.A.Mey., which was distinguished from Gnidia by the absence of petaloid scales. This character is now known to be vari-able within both Gnidia and Lasiosiphon, and Arthroso-len was treated as a synonym of Gnidia by Peterson (1959, 1978). The three species with pentamerous fl ow-ers should, however, be included in Lasiosiphon. Com-binations in Lasiosiphon exist for two of the species, viz. L. polycephalus (C.A.Mey.) H.Pearson and L. caloceph-alus (C.A.Mey.) Domke, but not for the third, Gnidia sericocephala.Lasiosiphon pedunculatus (Beyers) J.C.Manning & Boatwr., comb. nov. Gnidia pedunculata Beyers in Bothalia 32: 79 (2002). Type: South Africa, Western Cape, 3118 (Vanrhynsdorp): Knersvlakte, Olifants River Settlement 316, near Eastern border, (–BC), 6 Aug. 1993, Le Roux & Hilton-Taylor 27 (NBG, holo.!; K, PRE, iso.).Lasiosiphon sericocephalus (Meisn.) J.C.Manning & Boatwr., comb. nov. Arthrosolen sericocephalus Meisn. in DC., Prodromus systematis naturalis regni vegetabilis 14, 2: 561 (1857). Gnidia sericocephala (Meisn.) Gilg. ex Engl.: 634 (1921). Type: South Africa, ‘In mont. Macalisberg Caffrariae’, Zeyher 1494 (G-DC, holo.).ACKNOWLEDGEMENTSWe thank Hester Steyn (PRE) for providing images of the Acocks collections of this species, and Elizabeth Parker, Rose Smuts and Mervyn Berowsky for assist-ance in the fi eld.REFERENCESBEAUMONT, A.J., EDWARDS, T.J., MANNING, J.C., MAURIN, O., RAUTENBACH, M., MOTSI, M.O., FAY, M.F., CHASE, M.W. & VAN DER BANK, M. 2009. Gnidia (Thymelaeaceae) is not monophyletic: taxonomic implications for Thymelaeoideae and a partial new generic taxonomy for Gnidia. Botanical Journal of the Linnean Society 160: 402–417.BEYERS, J.B.P. 2002. A new species of Gnidia from the Knersvlakte, Western Cape, South Africa. Bothalia 32: 79–81.BREDENKAMP, C.L. & BEYERS, J.P.J. 2000. Thymelaeaceae. In O.A. Leistner, Seed plants of southern Africa: families and gen-era. Strelitzia 20: 544–546. National Botanical Institute, Pretoria. DE CANDOLLE, A.P.. 1857. Prodromus systematis naturalis regni vegetabilis 14, 2. Treuttel & Würtz, Strasburg.ENGLER, H.G.A. 1921. Die Pfl anzenwelt Afrikas 3, 2. Engelmann, Leipzig.HOLMGREN, P.K., HOLMGREN, N.H. & BARNETT, L.C. 1990. Index Herbariorum. Part 1: The Herbaria of the World. New York Botanical Garden, New York. PETERSON, B. 1959. Some interesting species of Gnidia. Botaniska Notiser 112: 465–480. PETERSON, B. 1978. Thymelaeaceae. In R.M. Polhill, Flora of tropi-cal East Africa: 1–37. Crown Agents for Overseas Governments and Agencies, London. VAN DER BANK, M., FAY, M.F. & CHASE, M.W. 2002. Molecular phylogenetics of Thymelaeaceae with particular reference to African and Australasian genera. Taxon 51: 329–339.VAN DER MERWE, H. 2010. Wild fl owers of the Roggeveld and Tan-qua. H. van der Merwe, Calvinia. WRIGHT, C.H., 1915. Thymelaeaceae. In W.T. Thiselton-Dyer, Flora capensis 5: 1–81. Reeve, London. J.C. MANNING* and J.S. BOATWRIGHT***Compton Herbarium, South African National Biodiversity Institute, Private Bag x7, 7735 Claremont, Cape Town / Research Centre for Plant Growth and Development, School of Life Sciences, University of KwaZulu-Natal, Pietermaritzburg, Private Bag X01, Scottsville 3209, South Africa. Email: J.Manning@sanbi.org.za.**Department of Biodiversity and Conservation Biology, University of the Western Cape, Private Bag x17, 7535 Belville, Cape Town. Email: jboatwright@uwc.ac.za.MS. received: 2012-08-01.FIGURE 3.—Distribution of Lasiosiphon rigidus.

Lasiosiphon rigidus, a new species from the Tankwa Karoo and two new combinations in the genus for South Africa

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Lasiosiphon rigidus, a new species from the Tankwa Karoo and two new combinations in the genus for South Africa

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