Aspalathus nickhelmei C.H.Stirt. & Muasya, 2016

Stirton, C. H. & Muasya, A. M., 2016, Seven new species and notes on the genus Aspalathus (Crotalarieae, Fabaceae) *, South African Journal of Botany 104, pp. 35-46 : 42-44

3.6. Aspalathus nickhelmei C.H.Stirt. & Muasya , sp. nov.

Type: South Africa. Western Cape Province, Riversdale (3421): 10 km NW of Stilbaai, near Voelfontein (− AD), 18 Sep. 2011, Helme 7168 ( BOL, holo.!) .

Tall laxly branching shrub to 1.7 m tall, reseeder. Stem single, pale brown with irregular network of peeling grey to yellowish bark strips; leaf bases woody, persistent. Stems arising from about 70 cm high and regularly up the stem, semi-erect tending to horizontal when flowering; young branches densely silvery velutinous. Leaves congested, arranged in clusters of up to 6–12 leaflets. Lea fl ets 8–11 mm long, linear, upper surface flattish, lower convex, soft, semi-erect to patent, mostly incurved, appressed velutinous, silvery-grey. In fl orescences unifloral, on lateral short shoots, many, scattered along seasonal branches. Flowers 10–15 mm long, all petals bright sulphurous yellow, longer than leaves; pedicel <1 mm long, tomentose; bracts and bracteoles 3–4 mm long, linear, pubescent. Calyx 11–12 mm long, campanulate, appressed velutinous, hairy inside; teeth dark green, broadly lanceolate, equal, displayed outwards, strongly net-veined, 5–6 mm, laterals broadest, 3 mm wide, soft; tube 4–5 mm long, pale yellowish green; slightly shorter than lobes. Standard blade 14 × 15 mm, broadly ovate, margin ciliate, emarginate, back hairy throughout, apex of front sparsely hairy; claw 2.5–3.0 mm, narrow, recurved. Wing blades 12 × 5 mm, broadly cultrate, glabrous; petal sculpturing present, upper basal and upper central, comprised of 5–6 rows of 12–15 lunate costal pockets becoming transcostal lamellate in a depression near the auricle; claw 4 mm, strongly upcurved. Keel petals 10 × 4 mm, blades fused, glabrous, auriculate, pointed, with spurred pocket, claw 5 mm long, tapering. Androecium 10 mm long with 5 basifixed and 5 dorsifixed, versatile anthers. Pistil 8 mm long; ovary 5 mm long, shaggy, ovules 2; style upcurved, bent midway, hairy along upper margin to point of inflecture; stigma inward facing. Fruits 10 × 4 mm (immature), obliquely ovate; densely shaggy, style persistent; immature fruits kidney-shaped; seeds khaki, hilum subterminal. Fig. 8.

3.6.1. Etymology

The specific epithet nickhelmei honours the Cape Town based botanist Nick Helme who discovered this species, and who has rediscovered many poorly known or forgotten species.

3.6.2. Diagnostic characters

Aspalathus nickhelmei is a striking new species that falls into Dahlgren's (1988) Group 34: Laterales. The species is similar to A. joubertiana Eckl. & Zeyh. but differs in its lax much-branched, floppy shrub habit to 1.7 m (versus ascending shrublet to 0.7 m); filiform bracts and bracteoles (versus dentate or subulate bracts and bracteoles); densely hairy (versus almost glabrous) standards; and with spurred pocket (versus non-spurred) keel.

3.6.3. Distribution and habitat

Aspalathus nickhelmei is thus far known from a single small population on a rocky, north facing limestone ridge in the Stilbaai region of the southern Cape, and is found in Canca Limestone Fynbos (FFI 3) ( Rebelo et al., 2006) at an elevation of about 90 m ( Fig. 5 ). Flowering takes place in September and October, and the species appears to be a fast growing post-fire specialist, as the only specimens were observed in veld that had burned three years before, and no plants were observed in similar nearby unburned veld.

3.6.4. Conservation status

Aspalathus nickhelmei appears to be rare and localised, and no previous collections are known. This may be partly due to the assumed biology of the species, which is likely to be a fast growing, short lived perennial that flowers only for the first 4 or 5 years after fire, and then persists in mature veld as a soil stored seed bank. This ecological trait is a relatively common feature of the genus. The only known population consists of a few flowering plants, outside a protected area, and close to a recently constructed road. The species was discovered during an environmental impact assessment. Nick Helme assessed (personal communication) this species to be critically endangered (CRD; population size estimated to number fewer than 50 mature individuals) under the IUCN Red list categories and criteria ( IUCN, 2001), but notes that the species may be under-collected due to its apparent need for fire in order to stimulate germination and flowering. Anecdotal evidence from local farmers suggests that it probably also occurs on the plateau higher up in the local “backlands”.

3.6.5. Additional material studied

South Africa. Western Cape: 3421 (Riversdale): near Voelfontein , 10 km NW of Stilbaai (− AD), 20 Oct. 2014, Stirton and Bello 14,091 ( BOL, GRA, K, NBG, PRE) .

Figures

Fig. 8. Aspalathus nickhelmei. (A) habitat;(B) habit; (C) fruiting branches;(D) portion of flowering shoot; (E) front view of flower; (F) side view of flower; (G) portion of fruiting shoot; (G) young fruit.

Fig. 5. Known distribution of Aspalathus barbigera (open circle), A. eriocephaloides (cross), A. eustonbrownii (black circle), A. macrocarpa (grey square), A. modesta (black square), A.nickhelmei (black triangle) and A. usnoides (grey circle) in Western and Eastern Cape Provinces.