Indigofera magnifica Schrire & V.R. Clark, 2015

Clark, V. Ralph, Schrire, Brian D. & Barker, Nigel P., 2015, Two new species of Indigofera L. (Leguminosae) from the Sneeuberg Centre of Floristic Endemism, Great Escarpment (Eastern and Western Cape, South Africa), PhytoKeys 48, pp. 29-41 : 29

Indigofera magnifica Schrire & V.R. Clark sp. nov. Figs 1 , 2 ; Plate 1

Diagnostic characters.

Indigofera magnifica is morphologically similar and most closely related to Indigofera meyeriana Eckl. & Zeyh., but differs in its prostrate, compact, densely matted habit (vs. laxly spreading, less dense and diffuse habit), sparsely to moderately strigose becoming reddish-maroon and glabrescent stems (vs. green-grey to canescent), fewer flowers ( ± 3-8) per raceme (vs.>8), brighter, more vivid pink flowers (vs. paler pink), and sparsely, appressed hairy pods (vs. spreading hairy pods). The overall colour of plants of Indigofera magnifica is a darker green than the generally grey-green to grey appearance of Indigofera meyeriana . Indigofera meyeriana is common and widespread in the Western Cape and western Northern Cape Provinces, and also occurs on the Sneeuberg.

Type.

South Africa, Western Cape Province, 3224AA, Plaas 113: summit plateau of the Koudeveldberge, Murraysburg District, Sneeuberg. 32°10'32"S, 24°01'41"E, 2134 m, 9 December 2011, Clark VR & Moholwa TT 206 (K, holotype; GRA, MO, NBG, NSW, PRE, S, isotypes).

Description.

Prostrate suffrutex 20-50 mm tall, densely to laxly matted, much branched. Stems slender, terete to ribbed, sparsely to moderately strigose with whitish biramous hairs, glabrescent later, reddish-maroon; stoloniferous, often rooting from nodes, arising from a woody rootstock. Leaves alternate, digitately trifoliolate, petiole 2-8 mm long, scattered with pearl bodies at base of leaflets. Stipules 1-2 mm long, up to 0.5 mm wide at base, lanceolate, attenuate, falcate, often recurved at apex, ± membranaceous, gland-tipped, reddish. Stipels absent. Terminal leaflet 1.5-5.5 mm × 1-3 mm, obovate, apex emarginate, truncate or rounded, base cuneate, upper surface glabrous or sparsely appressed strigose, paler than below; lower surface more densely strigose and slightly rugose; margins somewhat thickened, often appearing slightly involute, often reddish; lateral leaflets similar. Racemes (10)20-70 mm long, many times longer than the subtending leaf, including a peduncle of (6)11-55 mm, becoming flattened, appearing soft-tissued on drying; ± 3-8 flowered; bracts 0.5-1.5 mm long, lanceolate-subulate, recurved at apex, caducous. Pedicels 0.75-1.5 mm long, becoming recurved in fruit. Flowers 4.5-6.5 mm long. Corolla vivid fuchsia-pink. Calyx 1.5-2.5 mm long, lobes triangular, 0.75-1.4 mm, ± equaling the tube, ± sparsely strigose appressed. Standard 5.5-6.5 mm long, up to 5 mm wide, broadly obovate, tapering to a short claw at the base; blade sharply reflexed upwards for distal half of length; apex rounded to emarginate; dorsal surface glabrous, often with translucent, short stripes. Wings 5-6 mm long, unguiculate, shortly clawed at base, asymmetrically obovate towards apex. Keel petals 5-6.5 mm long, valvately connate distally, lateral spurs to 1 mm long, distal margin curving upwards to base of the keel to an obtuse apex; claws ± 2 mm long, broadening from the base. Stamens 4-5 mm long, alternately long and short, the 9 fused stamens free for ± 1 mm distally; anthers uniform. Ovary densely strigilose laterally, glabrous along upper margin; stigma capitate. Pods (9)11-15 mm long, up to 3.5 mm wide, cylindrical, inflated, shiny, reddish-green becoming reddish-brown, sparsely strigose, explosively dehiscent with the valves twisting. Seeds 4-6, 1.5 × 1.5 mm, ± quadrate, dark green.

Etymology.

The specific epithet magnifica is derived from the Latin adjective magnicus - a - um (a. splendid, magnificent) and is named for the magnificent, showy, vivid fuchsia-pink flowers.

Distribution and ecology.

Indigofera magnifica is confined to the summit plateau of the Toorberg-Koudeveld-Meelberg in the western Sneeuberg, between 1700-2150 m. The species is occasional to abundant, found exclusively on the dolerite-derived loamy-clays and black turf soils typical of this plateau. The vegetation type is Karoo Escarpment Grassland (Gh1, Mucina and Rutherford 2006), typical of high altitudes in the Sneeuberg mountain complex, with the dominant grass species being Tenaxia (= Merxmuellera ) disticha (Nees) N.P. Barker & H.P. Linder. Indigofera magnifica is particularly abundant on the highest parts of the plateau near the eastern and southern scarps, where it forms large colonies. It compliments a suite of several local endemics only found in the western Sneeuberg, including Acmadenia sp. nov., Erica passerinoides (Bolus) E.G.H. Oliv., Euryops dentatus B. Nord. and Faurea recondita Rourke & V.R. Clark ( Clark et al. 2009, 2012, Rourke et al. 2013).

Conservation status.

While the extent of occurrence (EOO) of Indigofera magnifica is small (ca. 30 km2), it is common (probably>10 000 individuals) in its restricted area. There are no obvious risks from the current land-use of livestock grazing: plants do not show evidence of damage from foraging or trampling. The remote, rocky high-altitude habitat renders it relatively safe from other detrimental land-use. Already restricted to summit elevations, it is however potentially at risk from global climate change. Any potential wind farm proposals for the Toorberg-Koudeveld-Meelberg would place this species at serious risk. The category VULNERABLE (Vu D2) is thus recommended.

Further collections and localities.

South Africa, Western Cape Province (straddling the provincial boundary with the Eastern Cape Province), 3223BB & 3224AA, Farms Plaas 113, Annex Koudeveld 114, Koudvelds Hoogte 117, Annex Onder Hoogde 116: summit plateau of the Koudeveldberge and Meelberg, Graaff-Reinet and Murraysburg Districts, Sneeuberg. ca. 32°10-11'S 23°59'E, ca. 2100 m, 25 November 2006, Clark VR & Te Water Naudé T 335 (GRA, K).

-Western Cape Province, 3224AA, Farm Quaggas Drift 108: Toorberg summit plateau, next to stream ca. 100 m from edge of escarpment, Murraysburg District, Sneeuberg. 32°08'46"S, 24°04'31"E, 1780 m, December 2007, Clark VR & Pienaar C 511 (GRA, K).

Figures

Figure 1. Analytical drawings of Indigofera magnifica Schrire & V. R. Clark, all drawn from the type collection (Clark VR & Moholwa TT 206) A growth habit B stoloniferous habit C trifoliolate leaf with stipules D terminal leaflet, underside E flower, front view F bud, side view G calyx H standard petal I wing petal J keel K staminal sheath L pistil M infructescence N pod O dehiscent pod P seed. Drawings by M. Tebbs.

Plate 1. Indigofera magnifica Schrire & V. R. Clark, plants in situ on the Koudeveldberge, Sneeuberg (Western Cape Province; Clark VR & Moholwa TT 206) A inflorescence B fruits C typical prostrate growth habit D mountain summit habitat. Photographs by V. R. Clark.

Figure 2. Known distributions of Indigofera magnifica Schrire & V. R. Clark (△) and Indigofera asantasanensis Schrire & V. R. Clark (○).