Ceropegia gilboaensis Heiduk, N. R. Crouch & D. Styles 2023, sp. nov.
Creators: name: Heiduk, Annemarie
name: Crouch, Neil R.
name: Styles, David G. A.
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Gentianales
Apocynaceae
Ceropegia
Ceropegia gilboaensis

description: Ceropegia gilboaensis Heiduk, N.R.Crouch & D.Styles sp. nov. (Figs 3, 4 A−E, 5A)   
 Diagnosis: —Plants of Ceropegia gilboaensis are perennial tuberous succulents with a prostrate growth habit, ovate to elliptic leaves, verrucose follicles, and a cylindrical-campanulate corolla, that can be separated from C. ngomensis (Figs 1I, 5B) in lacking the distinctly keeled or fluted corolla lobe bases that embed the gynostegium forming a characteristic 5-star shaped corolla mouth in C. ngomensis. The basally fused corolla lobes of C. gilboaensis have transverse burgundy bands but are purple-mottled in C. ngomensis. In C. gilboaensis, the inner corona lobes are adpressed to the back of the stamens along their full length and closely proximate to subconnivent over the style-head, whilst in C. ngomensis they are short and only adpressed to the base of the stamens. The outer corona lobes are deeply bifid in C. gilboaensis but undivided to form five cups with incurved margins in C. ngomensis.   
 Type: — SOUTH AFRICA. KwaZulu-Natal, the Karkloof, Mt Gilboa, ca. 1620 m, 12 November 2020, D. G. A. Styles & A. Heiduk 5841 (holotype; NU0092539!).   
 Description: —Perennial dwarf herb. Root a subterranean tuber, 20–40 mm in diameter, ca. 20 mm high, somewhat depressed on upper side, rounded below. Stems 1 or 2, up to 150 mm long, produced annually, branched sparingly at base, slender, creeping, prostrate, shortly pubescent. Leaves in 3–6(–8) pairs, shortly petiolate (to 1.7 mm long), lamina elliptic-ovate, 10–12 × 7–9 mm, ciliate with white hairs along the thin often purplish margins, pubescent above and below, venation prominent on lower surface and recessed on upper surface, basally rounded, apically acute. Flowers 1(–2) lateral at nodes, open in succession, with pungent fetid, slightly acidic-fecal floral scent; pedicels slender, pubescent, 6–7 mm long. Sepals narrowly triangular, 2.2–3.7 mm long, sparsely pubescent. Corolla steep cylindricalcampanulate, ca. 13–14 mm across, corolla lobes spreading, divided into fused and unfused section ± halfway; tube 4.5–6.3 mm deep, velvety, glabrous (rarely with sparse white trichomes on margins of corolla lobe tips), cream within with raised, transverse burgundy bands that proximally are more entire than distally; lobes narrowly triangular, 3.3–5.4 mm long, keeled, concave above, proximally cream with raised burgundy striations, distally velvety and brownish-red to rarely olive-green. Gynostegium sessile, glabrous, dark purple. Gynostegial corona 3.6–4.4 mm in diam., 2.0– 3.1 mm high, of staminal and interstaminal parts, interstaminal (outer) corona lobes joined to form a cup with V-shaped outer margin, deeply bifid, lobules ca. 0.3 mm long, falcate, inclined towards the inner lobes; staminal (inner) corona lobes adpressed to stamina along their entire length and incumbent on style-head, linear, ca. 1.7 × 0.3 mm, apices inclined over the staminal column, closely proximate to subconnivent. Pollinarium pollinia sagittate, ca. 450 × 400 μm, brownish, insertion crest ca. 250 μm long, stramineous; caudicles ca. 90 μm long; corpusculum sagittate, ca. 315 × 140 μm, brown. Follicle with both mericarps developing, erect, ca. 40–45 mm long and 4 mm at widest point, verrucose, green flecked with purple, maturing to purple-brown. Seeds ovate-elliptic, ca. 6 × 2 mm, brown, comose, coma ca. 7 mm, white.   Additional material examined:  
 Ceropegia gilboaensis: SOUTH AFRICA. KwaZulu-Natal, the Karkloof, Mt Gilboa, ca. 1630 m, 03 April 2022, D. G. A. Styles & A. Heiduk 6032 (NU 0092540!; fruiting material).   
 Distribution and ecology: — Ceropegia gilboaensis is to date known only from the Karkloof in the KwaZulu-Natal Midlands, South Africa. It is the only representative of the genus documented from the Karkloof, and is considered endemic there, at elevations of 1320−1670 m. This new species is found within grassland, growing exposed in shallow soil on the margins of, and in between, dolerite rock outcrops. Common grasses at the sites include Aristida junciformis Trin. et Rupr. (1842: 143) and Sporobolus natalensis (Steudel 1855: 154) Durand & Schinz (1894: 822). Associated herbaceous species include Aloe neilcrouchii Klopper & Smith (2010: 95), Crassula dependens Bolus (1881: 391) and Ledebouria sandersonii (Baker 1870: App. 5) Venter & Edwards (2003: 50).   
 The national vegetation map shows that C. gilboaensis occurs in Midlands Mistbelt Grassland and Mooi River Highland Grassland (South African National Biodiversity Institute 2006 –2018). In this area, Midlands Mistbelt Grassland appears to have been mapped as occurring below a contour approximating an elevation of 1500 m, and Mooi River Highland Grassland above this. However, this likely represents an over-simplification of the floristics in contact areas, where C. gilboaensis occurs just above 1500 m.   
 Midlands Mistbelt Grassland is described as “forb-rich, tall, sour Themeda triandra [Forsskal (1775: 178)] grasslands transformed by the invasion of native Ngongoni grass (Aristida junciformis subsp. junciformis). Only a few patches of the original species-rich grasslands remain.” (Mucina et al. 2006: 422). This vegetation type is “Endangered (one of the most threatened vegetation types of KwaZulu-Natal)” according to Mucina et al. (2006: 423). Furthermore, the Mistbelt of KwaZulu-Natal has been identified as an important centre of endemism (Mucina et al. 2006), although not yet formally recognized as such (Mucina et al. 2006; Van Wyk & Smith 2001). More limited floristic information is provided on Mooi River Highland Grassland, which is also considered threatened, but with the status of Vulnerable rather (Mucina et al. 2006).   
 Phenology: —Seen in flower from October to December, and in fruit from January to April.   
 Etymology: — Ceropegia gilboaensis is named for the type locality at Mt Gilboa in the Karkloof, SouthAfrica, where it was discovered in 2008 by Isabel Johnson, a field botanist, ecological consultant and dedicated conservationist.   
 Conservation Status: — Ceropegia gilboaensis is only known from two localities 7.5 km apart from each other. At each locality, plants were observed within an area of less than 1 km 2. However, a study of aerial imagery indicates that within the surrounding landscape there may be a further 35 km 2 of similar habitat in which C. gilboaensis could potentially occur. The total number of plants is estimated at less than 250 individuals. The grassland habitat at one of the two localities suffers from the trampling effects of cattle, but does not otherwise appear to be under anthropogenic threat. The species’ conservation status is suggested as Endangered (EN) under IUCN criteria B2(a)(b)(iii) and D (IUCN Standards and Petitions Subcommittee 2019).
description: Published as part of Heiduk, Annemarie, Crouch, Neil R. & Styles, David G. A., 2023, Ceropegia gilboaensis (Apocynaceae), a new species from the Midlands of KwaZulu-Natal, South Africa, pp. 125-136 in Phytotaxa 591 (2) on pages 129-133, DOI: 10.11646/phytotaxa.591.2.4, http://zenodo.org/record/7797469