Polhillia fortunata B. du Preez 2021, sp. nov.
Creators: name: du Preez, B.
name: Dreyer, L. L.
name: Stirton, C. H.
name: Muasya, A. M.
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Fabales
Fabaceae
Polhillia
Polhillia fortunata

description: 3. Polhillia fortunata B.du Preez, sp. nov. (Fig. 11)
Type: South Africa, Western Cape, 3321 (Ladismith): Vanwyksdorp District, Farm Waterval, about 1.5 km east of homestead along road to Herbertsdale (— CD), 23 Sept 2018, B. du Preez 564 (BOL, holo.!; K, MO, NBG, PRE, PRU, SCHG, iso.!)
Erect shrub up to about 2 m tall, sprouting from a woody rootstock. Branches silky-sericeous when young, older branches unknown. Stipules 2.0 — 4.0(— 6.0) mm long, silvery. Lea fl ets oblanceolate, grey-green, silky-sericeous, partially conduplicate, arcuate, apex apiculate, base cuneate, terminal leaflet 3.0 — 8.0 X 1.5 — 3.5 mm; lateral leaflets 3.0 — 7.5 X 1.0 — 3.5 mm; leaves subsessile. In fl orescence 2 — 5 flowered terminal cluster, pseudo-pedunculate, pseudo-peduncles up to 7.0 mm long; pedicel up to 7.0 mm long; bract ± 1 mm long, linear. Flowers yellow, 9 — 12 mm long. Calyx 3.5 — 4.8 mm long, lime-green, shortly villous; tube 2.5 — 3.5 mm long; dorsal teeth broadly triangular, 1.0 — 1.5 mm long, fused for less than one third of their length, apex acute; ventral teeth triangular, 1.0 — 1.5 mm long, fused for ± half their length, converging, apex acute. Standard 11.5 — 13.5 mm long; claw linear, 3.5 — 5.0 mm long; lamina broadly ovate, 9.0 — 10 X 11.5 — 13.5 mm, apex emarginate, base cordate; back shortly sericeous only on and around apical half of midline. Wing petals 10.1 — 11.1 mm long, slightly longer than keel; claw 3.0 — 4.0 mm long; lamina obovate, 8.4 — 9.3 X 3.7 — 4.1 mm, glabrous, apex obtuse, base auriculate, triangular and oblong depression with lamellate sculpturing. Keel petals 9.2 — 10.5 mm long; claw 3.0 — 4.0 mm long; lamina broadly lunate, 7.1 — 7.7 X 3.5 — 4.2 mm, pilose along front edge, apex acute-squared, base auriculate-truncate. Stamens basifixed anthers 1.1 — 1.4 mm long, carinal anther 0.9 — 1.0 mm long, dorsifixed anthers 0.5 — 0.6 mm long; staminal tube 6.8 — 9.6 mm long, unfused portion spreading somewhat, sub-erect, loosely arranged around style. Pistil 9.2 — 10.9 mm long; ovary 5.9 — 7.0 X 1.0 — 1.2 mm, ovules 10 — 12; style usually at about 70 — 90̊ angle, height of curvature 2.5 — 3.0 mm, glabrous except basally. Fruit indehiscent, plicate, straight or falcate toward apex, sericeous, olive green before ripening, 21.0 — 25.0 X 2.5 — 3.0 mm, ripe fruit unknown. Seed unknown.
Etymology
The specific epithet is a direct translation from Latin meaning “lucky”. This epithet was selected as the discovery of this species was fortuitous. The area in which this species occurs was burnt in a massive fire for the first time in nearly 100 years in February 2018, allowing profusion of resprouting shrubs to be visible from the road in what was previously near-senescent Renosterveld vegetation.
Diagnostic characters
Polhillia fortunata is morphologically similar to P. obsoleta and P. ignota, but also shares morphological characters of Overberg Polhillia species. The presence of pseudo-peduncles comprised of 2 — 5 flowers resembles P. obsoleta and P. ignota, but the leaves are densely silvery pubescent, similar to P. pallens and P. xairuensis. This species bears the strongest resemblance to the Swartland endemic P. ignota based on the dense arrangement of flowers on a pseudo-peduncle and the densely pubescent and plicate fruit. It, however, differs from P. ignota in having falcate fruit (versus straight); leaves up to 8.0 X 3.5 mm, conduplicate, densely silky sericeous and arcuate (versus leaves up to 12.0 X 2.5 mm, flattened, green sericeous and straight); and pseudo-peduncles up to 7.0 mm long (versus up to 15 mm long). It also has comparatively long pedicels of up to 7.0 mm long, while pedicels of other Polhillia species never exceed 3.5 mm, with the exception of P. involucrata that has pedicels of up to 6.0 mm long.
Distribution, ecology and conservation status
Polhillia fortunata flowers from August to October. It is known only from the type location (Fig. 6B) where it grows in Montagu Shale Renosterveld (FRs 7) on south facing slopes and along a seasonal riverbed (Mucina and Rutherford, 2006). It appears to be highly localized, as much of the surrounding habitat appears to be unsuitable, even though much of the area is still in a natural state. This area is poorly explored botanically and other sub-populations may still be found (Vlok, pers. comm.). The population does not face any direct threats at present, as most of this area is used for wildlife breeding and there are no exotic tree species. Due to the arid nature of the area, fire is infrequent and the last fire in that area before the fire of January/ February 2018 was in the early 1920’s based on Muir’ s collection of P. connata in 1925. This single population consists of roughly 300 — 400 plants that were sprouting after the recent fire, while some seedling recruitment was also observed. The Red Data List status of this species is proposed as Vulnerable (VU D1) following the latest IUCN categories and criteria (IUCN, 2012).
Additional specimens examined
South Africa. WESTERN CAPE: 3321 (Ladismith): Vanwyksdorp District, Farm Waterval, about 1.5 km east of homestead along road to Herbertsdale (— CD), 29 Jun 2018, B. du Preez 501 (BOL, SCHG).
description: Published as part of du Preez, B., Dreyer, L. L., Stirton, C. H. & Muasya, A. M., 2021, A monograph of the genus Polhillia (Genisteae: Fabaceae), pp. 156-183 in South African Journal of Botany 138 on pages 169-170, DOI: 10.1016/j.sajb.2020.12.022, http://zenodo.org/record/10496862