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| Gymnosporia sekhukhuniensis Jordaan & A.E.van Wyk
in Jordaan & van Wyk, 2019.
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Abstract
Gymnosporia sekhukhuniensis, a new species from north-eastern South Africa, is described, illustrated, mapped, and compared with closely related species. It belongs to Gymnosporia sect. Buxifoliae, more specifically Group 1, the members of which are characterized by the capsules being (2)3(4)-valved, rugose or verrucose, and the seeds partially covered by the aril. The new species has a restricted distribution range and is near-endemic to the Sekhukhuneland Centre of Endemism. This biogeographical region rich in restricted-range plants is more or less congruent with surface outcrops of mafic and ultramafic igneous rocks belonging to the Rustenburg Layered Suite of the eastern Bushveld Complex. The range of the new species shows marginal intrusion into the far northern part of the nearby Wolkberg Centre of Endemism, where it is associated with dolomites of the Malmani Subgroup. Gymnosporia sekhukhuniensis is a suffrutex mainly associated with rocky outcrops in open savannah. Diagnostic characters include its dwarf habit (up to 1.6 m tall), capsules that are relatively small (5–8 mm long), woody, scaly-rugose, with hard pointed apices, and leaves that are very laxly arranged on the stems, with some often present on the thorns. Also included is a key to the 10 currently accepted species in G. sect. Buxifoliae Group 1. The taxonomic significance of capsule and seed characters for demarcating sections and species in the genus Gymnosporia is emphasized.
Keywords: endemism, Gymnosporia sect. Buxifoliae, morphology, sections, Sekhukhuneland, taxonomy, ultramafic soils, Wolkberg, Eudicots
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| FIGURE 1. Gymnosporia sekhukhuniensis, on the farm Hoogland 38JT, between Lydenburg (Mashishing) and Roossenekal in Mpumalanga province, South Africa. A. Plant with fruit; in natural habitat, amongst rocks of norite. B. Almost mature fruit.
Photographs: W. McCleland.
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| FIGURE 2. Gymnosporia sekhukhuniensis. A. Leafy branchlet with fruit. B. Twig with male flowers. C. Female flower. D. Male flower. E. Dehisced capsule with seed. F. Seed, with basal aril. Scale bar = 10 mm (A & B), 1 mm (C, D & F) and 2 mm (E). A from Winter 2585, B from Winter 2932, C from Schmidt 845, D from Stalmans 695, E & F from McMurtry 12408. Artist: Daleen Roodt. |
Gymnosporia sekhukhuniensis Jordaan & A.E.van Wyk, sp. nov.
Closely related to Gymnosporia heterophylla (Ecklon & Zeyher 1834–1835: 120) Loesener (1892: 207), with which it shares being a suffrutex with the stems angular-ribbed and in having capsules with a rugose surface, but from which it differs in the leaves being laxly arranged on the stems (vs. very densely and compactly), usually longer than 35 mm (vs. usually shorter than 20 mm), and capsules with apices apiculate (vs. rounded). Also related to the widespread G. buxifolia (Linnaeus 1753: 197) Szyszylowicz (1888: 34), from which it differs in being a suffrutex up to 1.6 m tall (vs. usually a shrub or tree more than 2 m tall), with stems angularribbed (vs. terete) and capsules 5–8 mm long (vs. usually less than 5 mm long), with apices apiculate (vs. not apiculate).
Etymology:— The specific epithet is derived from Sekhukhuneland, the region to which the species is largely confined.
Distribution:— Occurs along the north-eastern Great (Drakensberg) Escarpment of the Limpopo and Mpumalanga
Provinces of South Africa and is considered near-endemic to the Sekhukhuneland Centre of Endemism, with marginal
intrusion into the far northern adjoining part of the Wolkberg Centre of Endemism (Van Wyk & Smith 2001) (Fig. 3).
Common names:— The proposed common names for this plant are Sekhukhune spikethorn, sekhukhunependoring
(Afrikaans).
Marie Jordaan and Abraham van Wyk. 2019. Gymnosporia sekhukhuniensis (Celastraceae), A New Species from South Africa. Phytotaxa. 408(1); 69–76. DOI: 10.11646/phytotaxa.408.1.5
