Gymnanthemum koekemoerae H. Rob. & V.A. Funk, 2014

Robinson, Harold & Funk, Vicki A., 2014, Gymnanthemum koekemoerae (Compositae, Vernonieae), a new species from South Africa, PhytoKeys 36, pp. 59-65 : 61

Gymnanthemum koekemoerae H. Rob. & V.A. Funk sp. nov.

Type.

South Africa. Limpopo Province. Thohoyandou District. Thathe-Vonde Nature Reserve. Grassland at rocky outcrop near entrance, 1233 m, 22°55'10"S, 30°19'36"E [2230CD], 23 March 2002, Koekemoer 2273 (holotype PRE!, isotype US!). Figs 1 - 3 .

Description.

Sparsely branched shrubs 1.3-1.5 m tall; stems brown, terete and striate, hispid to hirtellous and gland-dotted, hairs unicellular, with short branches and spurs. Leaves alternate; petioles 3-4 mm long; leaf blades chartaceous, suborbicular, 4.5-6.5 cm long and broad, bases rounded to broadly obtuse, abruptly terminating at petiole, margins with c. 5 broad dentations above basal ¼, apex with broad obtusely triangular tip; adaxial surface dark green when dry, essentially glabrous, primary and secondary veins priminulous in shallow grooves, tertiary veins flush with surface; abaxial leaf surface somewhat paler, sparsely pilosulous on larger prominulous veins, surface with numerous yellow glandular dots; secondary veins widely spreading at 50-80° angles, usually 4 on each side, quaternary veins minimally prominulous. Inflorescence broadly corymbiform, terminal on stems and distal branches; peduncles 3-8 mm long, capitula 13-15 mm high; involucres 4-5 mm wide, to 7-8 mm wide when in fruit; involucral bracts subimbricate in c. 5 gradate series, round to oblong, 2-7 mm long, 2.5-3.6 mm wide, inner bracts somewhat ranked, apices broadly rounded to subtruncate, with broad rounded surface outside, greenish or brownish with darker and gland-dotted distal 1/4; florets 5 in a capitulum; corollas pale lavender, c. 9.5 mm long, essentially without hairs, sparsely gland-dotted outside, basal tube c. 5 mm long, funnelform distally, throat c. 0.5 mm long, lobes evenly tapered, c. 4 mm long; anther thecae c. 4.5 mm long, apical appendage triangular, c. 0.6 mm long, 0.25 mm wide; achenes c. 5 mm long, 10-ribbed, with numerous short, spreading setulae mostly on ribs, with glandular dots between ribs; pappus mostly c. 9 mm long, becoming tawny, of c. 90 crowded capillary bristles, bristles scarcely broadened distally.

Related taxa.

Gymnanthemum koekemoerae is closest to Gymnanthemum mespilifolium in its leaf pubescence, but it has an abrupt base on the leaf blade, totally unlike the narrow acumination in Gymnanthemum mespilifolium that gives the leaves of the latter a long-petiolate appearance. The blades of the new species are also more chartaceous, and the dentations of the leaf are more numerous and are as broad as long. The dentations in Gymnanthemum mespilifolium are long and narrowly acute, and are restricted to the distal 1/3 of the leaf blade.

Notes.

The holotype (PRE) has both flowering and fruiting material while the isotype (US) material is mostly fruiting. The specimen of the new species was distributed as Vernonia triflora Bremek. (now Gymnanthemum triflorum (Bremek.) H. Rob.) which has only 3 florets in its capitula, has stiffly and densely hispid stems, and has ovate to oblong leaf blades with hispidulous abaxial surfaces.

Etymology.

The species is named for Dr. Marinda Koekemoer (PRE) who collected the type material and who has done so much to further our knowledge of the Compositae of southern Africa.

Distribution.

This species is known only from the type locality.

Figures

Figure 1. Type specimens. A Photograph of the isotype (US) B Photograph of the inflorescence of the holotype (PRE).

Figure 2. Original Illustration of Gymnanthemum koekemoerae H. Rob. & V. A. Funk: A Habit B Abaxial surface of leaf C Head D Outer involucral bract E Inner involucral bract F Floret G Longitudinal section of floret showing anthers H Style I Achene with pappus. [Illustration by Alice Tangerini (US)]

Figure 3. Illustration of heads from the holotype: A Head when in flower B Head with mature achenes. Note: there is an increase in dark coloration on the more mature head, possibly caused by fungi. [Illustration by Alice Tangerini (US)]