Aspalathus dahlgrenii 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 : 36

3.1. Aspalathus dahlgrenii C.H. Stirt. & Muasya , sp. nov.

Type: South Africa. KwaZulu-Natal Province, Port Edward (3130): Umtamvuna Nature Reserve (− AA), 3 Dec. 2009, Abbott 9069 ( BOL, holo.!; K!, MO!, NBG!, NH!, NU!, PCE!, PRE!, S!, iso.) .

Robust erect shrubs up to 4 m tall, reseeder. Stems single, with a trunk up to 7.5 cm diam., bark brown with fine encrustations; branches erect to spreading, young branches densely silvery sericeous. Lea fl ets 5–8 mm long, needle-like, stiff, spreading, covered with silvery-grey, appressed pubescence, arranged in clusters of up to 6 leaflets. In fl orescences unifloral, on short brachyblasts, scattered in upper third of each branchlet. Flowers 10–11 mm long, yellow, exceeding leaves; pedicel 1 mm long, tomentose; bract 2–3 mm long, filiform, fewhaired; bracteoles 2.5 mm long, filiform. Calyx 8 mm long, oblongcampanulate, appressed sericeous inside and outside, margins with dense white tufts; lobes narrowly subulate, acuminate, terete, teeth 4 mm, green; tube 4 mm long, equal to teeth, yellowish. Standard blade 11 × 9 mm, broadly elliptic, emarginate; claw 3 mm wide, scarcely channelled, curved. Wing blades 5.5 × 2.0 mm, shorter than keel, glabrous, with raised ridge along the midline; petal sculpturing comprises 2–3 (4) rows of 13–17 small lunate costal pockets upper basal and upper central; claw 3 mm, slightly recurved. Keel petals 9.0 × 3.0– 3.5 mm; blades 6 mm wide, glabrous, apex obtuse, pocketed, fused; claw 3 mm long, ribbon–like, straight. Androecium 5 mm long; anthers with 5 shorter basifixed and 5 longer dorsifixed, versatile anthers. Pistil 8 mm long; ovary 1 mm long, shaggy, ovules 2; style straight to gently upcurved, hairy along upper margin. Fruits almost obliquely hemi-spherical (immature), style persistent; seeds unknown. Fig. 1.

3.1.1. Etymology

The specific epithet dahlgrenii honours the late Rolf Dahlgren who contributed so much to our understanding of the genus Aspalathus ( Dahlgren, 1988) and other Cape Fabaceae . The first author was fortunate to accompany him and Mrs. Anne Bean on a number of field trips; the highlight of which was finding the very rare tree-like A. bidouwensis Garab. ex R.Dahlgren , an event that stimulated interest in the genus.

3.1.2. Diagnostic characters

Aspalathus dahlgrenii is a distinctive species that falls into Dahlgren's (1988) Group 33: Calcicolae. It is similar to A. frankenioides DC. and A. gerrardii Bolus but differs in its 2–4 m tree-like (versus decumbent or ascending to 1.5 m) habit; and flowers 9–13 mm (versus 4–8 mm) long.

3.1.3. Distribution and habitat

Aspalathus dahlgrenii is known only from stream sides along the escarpment on the KwaZulu-Natal side of the Umtamvuna River ( Fig.2 ) in Pondoland-Ugu Sandstone Coastal Sourveld (CB 4) ( Mucina et al., 2006a). It occurs at about 180–430 m and flowers from December to January.

3.1.4. Conservation status

Aspalathus dahlgrenii is a reseeder that appears to be rare and localised, collected for the first time as recently as 2005. The species is fast growing and emerges as seedlings after fire. Based on its patchy distribution and few known localities, all in a small area less than 20 km 2, and that it may be threatened if fires are too frequent and if its preferred streamside habitats are unprotected, we evaluate the conservation status of this taxon as vulnerable (VU D2) under the IUCN Red list categories and criteria ( IUCN, 2001).

3.1.5. Additional specimens studied

South Africa. KwaZulu-Natal. 3030 (Port Edward): Nkwazamani, Maringo Flats (− AA), 24 Jan. 2010, Abbott 9078 ( PCE, PRU) ; Pont Outpost, Umtamvuna Nature Reserve (− AA), 3 Dec. 2005, Abbott 8299, 8899 ( PCE, PRU) ; Nilsen Farm, Port Edward (− AA), 30 Dec. 2009, Abbott 9069 ( BOL) ; 31 Dec. 2009, Abbott 9070 ( BOL) ; 5 Jan. 2010, Abbott 9071 ( BOL) ; Abbott 9085 ( PCE, PRU) .

Figures

Fig. 1. Aspalathus dahlgrenii.(A) habit of fire-killed plants; (B) habit of mature living plants; (C) flowering branches; (D) flowering shoot; (E) side view of flower preserved in FAA; (F) young fruits; (G) bark.

Fig. 2. Known distribution of Aspalathus dahlgrenii (grey circle) and A.spinifera (black circle) in Eastern Cape and KwaZulu Natal Provinces.

Fig. 3. Aspalathus spinifera. (A) habitat; (B) habit; (C) leaf fascicles on young shoot; (D) flowers; (E) flowering shoot.