Indigofera asantasanensis 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 : 29-32

Indigofera asantasanensis Schrire & V.R. Clark sp. nov. Figs 2 , 3 ; Plate 2

Diagnostic characters.

Indigofera asantasanensis is similar to Indigofera alpina Eckl. & Zeyh., but differs in its (3)5-7 foliolate leaves (vs. consistently trifoliolate leaves), leaflets 1.5-3 mm wide (vs. 4-16 mm wide), and stipules 1-1.6 mm wide (vs. 2-10 mm). Indigofera asantasanensis may also be confused with Indigofera burchellii DC., being similar in having digitately 5-7 foliolate leaves, but it has wider stipules (1-1.6 mm vs. <0.5 mm). Indigofera alpina is mostly confined to the mountains of the Eastern Cape, while Indigofera burchellii is almost exclusively a southern Great Escarment species, centred from the Roggeveldberge to the Eastern Cape Drakensberg; both of these species also occur in the Sneeuberg.

Type.

South Africa, Eastern Cape Province, 3225AC, Farm 360: mountain slopes above Suurkloof, behind the old town of Petersburg, east of the Nardousberg, now included in Asante Sana Private Game Reserve, Graaff-Reinet District, Sneeuberg. 32°15'18"S, 25°00'10"E, 1708 m, 10 December 2011, Clark VR & Moholwa TT 211 (K, holotype; GRA, MO, NBG, NSW, PRE, S, isotypes).

Description.

Decumbent to erect suffrutex 100-200 mm tall, much branched, densely leafy.

Stems slender, terete to strongly ribbed, angular, or longitudinally wrinkled, scattered with pearl bodies; moderately to densely strigose with spreading biramous hairs often crisped at the tips; reddish-brown, becoming woody below; a rhizomatous colony, diffusely branching from an indistinct woody rootstock. Leaves alternate, digitately (3)5-7-foliolate, petiole 1.5-5 mm long, deeply channelled above, scattered with pearl bodies at base of leaflets. Stipules 1.5-5 mm long, (0.75)1-1.6 mm wide, triangular to obliquely ovate-lanceolate, acuminate; amplexicaule, leaving annular sheath around stems, ± membranaceous. Stipels absent. Terminal leaflet (2.5)4-10 mm × (1)1.5-3 mm, obovate to oblanceolate, apex rounded, apiculate, often complicate; sparsely to moderately spreading or appressed strigose on both surfaces, hairs often coarser above than below, secondary venation ± prominent below; margins somewhat thickened, often appearing slightly involute; lateral leaflets similar. Racemes 25-120 mm long, many times longer than the subtending leaf, including a peduncle of 15-50 mm, moderately to densely strigose, scattered with pearl bodies; ± 12-35 flowered; bracts 3-4 mm long × ca. 1.5 mm, ovate-lanceolate, acuminate, caducous. Pedicels 0.5-2 mm long, reflexed. Flowers 6-7.5 mm long. Corolla deep pink, darker wine-red in bud. Calyx 2-3 mm long, lobes triangular to lanceolate, 1-2 mm long, ± equaling to twice as long as the tube, ± sparsely to densely strigose. Standard 5.5-6 mm × 5.5-6.5 mm, broadly obovate, tapering to a short claw at the base; blade sharply reflexed upwards for distal half of length; apex round to emarginate, dorsal surface glabrous, often with translucent, short stripes. Wings 5.5-6.5 mm long, unguiculate, shortly clawed at base, asymmetrically obovate towards apex. Keel petals 5-6 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 4.5-5.5 mm long, alternately long and short, the 9 fused stamens free for ± 1 mm distally; anthers uniform. Ovary glabrous, stigma capitate. Pods 17-25 mm long, up to 3.5 mm wide, cylindrical, reddish-brown, glabrous, explosively dehiscent with the valves twisting. Seeds 4-5, 3 × 2 mm, subcylindrical, green.

Etymology.

The species is named for the Asante Sana Private Game Reserve, the owners and managers of which have been generous and instrumental in facilitating biodiversity research in the Sneeuberg. The known range of this species is almost entirely confined to this property.

Distribution and ecology.

Indigofera asantasanensis is currently only known from a small area in the eastern Sneeuberg from the Nardousberg to the Tandjiesberg-Coetszeesberg area behind the old town of Petersburg (now incorporated in the Asante Sana Private Game Reserve) and Pearston. The Tandjiesberg here is not to be confused with the more familiar Tandjiesberg (32°23'13"S, 24°42'13"E) of lower altitude and closer to Graaff-Reinet. Indigofera asantasanensis occurs from the mid-upper slopes to the summit plateau, ca. 1500-2200 m; it is locally abundant in Karoo Escarpment Grassland ( Mucina and Rutherford 2006), dominated in this locality by inter alia Tenaxia disticha , Euryops trilobus Harv. and Helichrysum splendidum (Thunb.) Less. Indigofera asantasanensis occurs in loamy, rocky soils derived from both dolerite and Beaufort Group sandstone substrates. It compliments several local endemics, including Euryops proteoides B. Nord. & V.R. Clark and Euryops exsudans B. Nord. & V.R. Clark ( Nordenstam et al. 2009).

Conservation status.

While the extent of occurrence (EOO) of Indigofera asantasanensis is small (ca. 15 km2), it is abundant (probably>10 000 individuals) in its restricted area. There are no obvious risks from the current land-use of game farming. The remote, rocky high-altitude habitat renders it relatively safe from other detrimental land-use. Already restricted to the higher elevations, it is potentially at risk from global climate change. Local infestations of the highly invasive grass Nassella trichotoma (Nees) Hack. ex Arechav. on Asante Sana Private Game Reserve and adjacent properties do constitute a potential risk to the habitat of Indigofera asantasanensis . The category Vulnerable (VU D2) is thus recommended.

Further collections and localities.

South Africa, Eastern Cape Province, 3225AC, Farm 360: mountain slopes above Suurkloof, mountains behind the old town of Petersburg, east of the Nardousberg, now in Asante Sana Private Game Reserve, Graaff-Reinet District, Sneeuberg. 32°15'17"S, 25°01'04"E, 1853 m, 6 December 2005, Clark VR & Coombs G 208 (GRA, K).

-Farms Paardekom 5 and Annex Waterkloof 2: upper mountain slopes (Tandjiesberg-Coetszeesberg) ca. 15 km east of the Nardousberg (Sneeuberg), behind Pearston, Graaff-Reinet District. 32°16'47"S, 25°05'25"E, ca. 1950 m, 13 December 2006, Clark VR & Coombs G 635 (GRA).

-Farm 360: mountain slopes above Suurkloof, mountains behind the old town of Petersburg, east of the Nardousberg (Sneeuberg), now in Asante Sana Private Game Reserve, Graaff-Reinet District 32°15'40"S, 25°10'10"E, 1550-2000 m, 31 March 2008, Clark VR & Crause C 2 (GRA).

-3224BB, Upper Waterkloof 352: eastern end of Nardousberg ridge-line (Sneeuberg), Asante Sana Private Game Reserve, Graaff-Reinet District. 32°14'48"S, 24°55'58"E, 2171 m, 2 April 2008, Clark VR & Crause C 34 & 65 (GRA).

Figures

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

Plate 2. Indigofera asantasanensis Schrire & V. R. Clark, plants in situ on the slopes above ' Suurkloof', Asante Sana Private Game Reserve, Sneeuberg (Eastern Cape Province; Clark VR & Moholwa TT 211) A inflorescence from the front B inflorescence from the side C infructescence D close up of a single pod E the digitately foliolate leaves F growth habit G Escarpment mountain habitat. Photographs by V. R. Clark.

Figure 3. Analytical drawings of Indigofera asantasanensis Schrire & V. R. Clark, all drawn from the type collection (Clark VR & Moholwa TT 211) A growth habit B digitately foliolate leaf with stipules C growth habit D stipule E calyx F standard petal G wing petal H keel I staminal sheath J pistil K infructescence L dehiscent pod M seed. Drawings by M. Tebbs.