Ursinia arida Magee & Mucina, 2014

1. Ursinia arida Magee & Mucina View in CoL , sp. nov.

Type:— SOUTH AFRICA. Northern Cape Province, Vioolsdrif (2817): Richtersveld, Eksteenfontein, S of Rooiberg and N of Klipbokkop at road to Hellskloof Canyon (–CD), 31 August 2006, Mucina 310806/07 (holotype NBG! , isotype K! ).

Erect to sprawling annual herb, 0.80– 0.25 m tall; single-stemmed or well branched at the base, branches spreading to decumbent. Leaves cauline, alternate, 12.0–40.0 × 5.0–15.0 mm, bipinnate, glandular-punctate, sparsely pilose; lobes lanceolate to linear, 1.0–8.0 × ± 0.5–1.5 mm, mucronate. Capitula radiate, heterogamous, ca. 20–35 mm in diam., solitary; peduncle 40–140 mm long at anthesis, sparsely pilose. Involucre hemispherical to sometimes campanulate, 4.0–5.0 × 10.0–15.0 mm, glabrous; involucre bracts 4- to 6-seriate, margins and apices somewhat scarious; outer bracts ovate, 1.0– 1.5 mm long, acute, outlined purplish black; middle bracts ovate, 2.0–3.0 mm long, acute, some outlined purplish black; inner bracts ovate, 3.0–4.0 mm long, without dark markings, apical appendages ovate to broadly ovate, obtuse. Receptacle paleate. Paleae scarious, apically with elliptic appendages, heteromorphic; outer broadly oblong, appendages narrower than limb; inner lorate, appendages only slightly broader than limb; appendages shorter than or equal to florets, not enclosing developing florets. Ray florets neuter, 12 to 20; lamina 6–12 mm long, yellow. Disc florets bisexual, numerous, yellow, 5-lobed; lobes cucullate, with sessile glandular trichomes. Anthers slightly sagittate at base; apical appendages cordate. Style terete; branches linear, truncate, sweeping hairs apically-dorsally. Pappus biseriate, white, outer scales 5, transversely obovate, inner scales 5, setaceous, unequally developed, some rudimentary. Cypselas oblanceolate, geniculate, ± 3.0 × 1 mm, heteromorphic, scattered, most white, granulate, some black, rugose.

Distribution and ecology: — Ursinia arida is confined to the Richtersveld and northern Bushmanland in the Northern Cape Province ( Fig. 3 View FIGURE 3 ) and should be considered an endemic of the Gariep Center of Endemism ( Van Wyk & Smith 2001). In the Richtersveld it occurs on a variety of substrates in vegetation types such as Dg 6 Helskloof Canyon Desert and Dg 2 Richtersberg Mountain Desert ( Jürgens et al. 2006). The species appears to be particularly common in quartz-rich patches both in the Richtersveld (SKr 11 Rooiberg Quartz Vygieveld) and in Bushmanland (SKr 18 Bushmanland Inselberg Shrubland, SKr 19 Aggeneys Gravel Vygieveld) within the Succulent Karoo Biome ( Mucina et al. 2006). We expect this species to be found also in southern Namibia, especially in the Fish River Canyon and in the desert landscapes of the Gariep River valley (upstream from Vioolsdrif and Noordoewer).

Diagnostic characters: — Ursinia arida shares the inconspicuous and transparent paleae appendages and acute involucral bracts with Ursinia nana but differs in that the inner paleae are lorate with elliptic appendages ( Fig. 2M View FIGURE 2 ), rather than oblong with small ovate appendages. The species has also often been misidentified as U. cakilefolia from which it differs in that the paleae are shorter than the florets and have elliptic appendages. In U. cakilefolia the paleae are longer than the florets, and therefore conspicuous, and have prominent scale-like, ovate to transversely ovate appendages ( Fig. 2K, L View FIGURE 2 ) that are brownish-yellow to brown-black and which enclose the developing florets giving the disc a reflective appearance ( Fig. 1I View FIGURE 1 ).

Additional specimens examined: — SOUTH AFRICA. Northern Cape Province: 2817 (Vioolsdrif): Vioolsdrif, Die Toon, E. of Richtersveld National Park (–AD), July 1995, Williamson & Williamson 5657 ( NBG) ; Richtersveld, Hellskloof Canyon, lower part close to bushman’s paintings (–CA), 31 August 2009, Mucina 310806/24 ( NBG) ; Richtersveld, E of Eksteenfontein and SW of Rooiberg Guest House (–CD), 29 August 2006, Mucina 290806/04 ( NBG) ; Richtersveld, Eksteenfontein, S of Rooiberg and N of Klipbokkop at road to Hellskloof Canyon (–CD), 31 August 2006, Mucina 310806/07 ( NBG) . 2819 (Ariamsvlei): 28 miles west of Pofadder (–DD), 23 May 1961, Schlieben 8984 ( NBG, NYBG). 2917 (Springbok): O’okiep (–DB), 28 September 1939, Thorus 39 ( NBG) . 2918 (Gamoep): 48 km E of Springbok, at the edge of Bushmanland (– AD), Goldblatt & Manning 11332 ( NBG) , Boatwright & Manning 641 ( NBG) ; Naib se Berg between Springbok and Aggeneys (–AD) Mucina 080905 /4 ( NBG) ; near Ratelkraal (–CA), 7 September 1950, Barker 6621 ( NBG) ; Areb, 30 miles NE of Springbok (–CB), 12 April 1926 (NBG), Barker 8363 ( NBG) ; 45 km E of Springbok on Pofadder road (–CB), 14 May 2000, Manning 2247 ( NBG) ; Bushmanland, on road Springbok to Aggeneys, Farm Kangas (–CB), 2 September 2006, Mucina 020906 /02 ( NBG) .