A rare new species of the genus Wiborgiella (Crotalarieae, Fabaceae)

Thenewspecies Wiborgiellaargentea isdescribed.Itiscloselysimilarto Wiborgiellaleipoldtiana and W.fasciculata butdiffersinitssingle-stemmedhabit,denselysericeousleaves,wingpetalsthatarelongerthanthekeelandde-tails of the fruit. It is known from the Robertson area where it occurs in Robertson Karoo, on rocky, south facing shale slopes. © 2014 SAAB. Published by Elsevier B.V. All rights reserved.

Most of the Wiborgiella species are highly localized with five of the species listed as threatened (critically endangered, endangered, vulnerable or critically rare), one listed as near threatened and three of least concern (Raimondo et al., 2009).This is partly due to the large scale transformation of habitat that has taken place in various parts of the Western Cape, and also to the small natural ranges of many of the species.
In this paper a new species from the Western Cape Province of South Africa is described.It was discovered by Mr. Nick Helme in 2012 during field surveys around the Vrolikheid Nature Reserve near Robertson, and this appears to be the first record of this species.

Materials and methods
Morphological data on the new species were gained through examination of herbarium material from NBG and in situ observations.Drawings were done using a stereoscope (WILD M5) with a camera lucida attachment.Similar to Wiborgiella leipoldtiana and W. fasciculata in its short calyx lobes, yellow flowers and long, inflated pods but differs in the densely sericeous leaves, wing petals that are slightly longer than the keel and linear pods that are longer than those of W. fasciculata.

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South African Journal of Botany

Distribution and habitat
The species is only known from a single locality and population, some 6 km east of McGregor, in the Breede River Valley (Fig. 3).The population occurs in Robertson Karoo vegetation (SKv7; Mucina et al., 2006) on steep, south-facing, rocky, shale slopes.Most of the population is found above the Strykhoogte Pass, with a few plants observed below the pass.A brief survey of the nearby slopes in May 2013 did not reveal a larger or more widespread population, and a brief survey of likely habitat in Vrolikheid Nature Reserve in August 2013 failed to yield the species.

Etymology
The species is named for the silvery appearance of the leaves and young vegetative parts.

Conservation status
The only known population is estimated to be between 100 and 200 plants, none of which are within the Vrolikheid Nature Reserve.The population covers an area of about 2 ha.About 30% of the population occurs within the road reserve, and the remainder is on private land that is heavily and regularly grazed and trampled by goats.The grazing clearly has an impact on the plants and habitat, although the woody nature and height of the plants seems to afford them an element of protection.It is possible that further fieldwork will show the species to be present within the Vrolikheid Nature Reserve (some 1 km to the north), where seemingly suitable habitat is present, and where grazing pressure is likely to be lower.The conservation status of the species is assessed as CR B1ab(iii) + 2ab(iii) using IUCN (2001) criteria.
j o u r n a l h o m e p a g e : w w w .e l s e v i e r .c o m / l o c a t e / s a j b caducous; bracteoles linear, 1.0-1.5 mm long, sericeous, caducous.Flowers 10-12 mm long, yellow, with brown streaks on inner surface of standard.Calyx ± 4-5 mm long, densely pilose, subequally lobed, upper sinus often deeper than the lateral or lower sinuses, carinal lobe narrower than the others; tube ± 3.5-4.0mm long; lobes ± 1.0-1.5 mm long, deltoid, tips glabrous on inner surface.Standard 8.5-12.0mm long, pilose along and around dorsal midrib in upper parts and flushed brown; claw linear, ±2.

3. 1
.1.Diagnostic characters and relationships The new species is similar to Wiborgiella leipoldtiana (Schltr.ex R. Dahlgren) Boatwr.& B.-E.van Wyk and W. fasciculata (Benth.)Boatwr.& B.-E.van Wyk in the short calyx lobes, yellow flowers and long, inflated pods.Although Wiborgiella humilis (Thunb.)Boatwr.& B.-E.van Wyk also has short calyx lobes, the pods are short, stipitate and elliptic to obovate.Wiborgiella argentea differs from W. fasciculata and W. leipoldtiana in its single-stemmed habit (W.fasciculata and W. leipoldtiana are multi-stemmed shrubs), densely sericeous leaves (leaves sparely sericeous in W. leipoldtiana and pilose in W. fasciculata), wing petals that are slightly longer than the keel (wing petals shorter than the keel in both W. leipoldtiana and W. fasciculata) and linear pods (the pods are oblanceolate to elliptic in W. leipoldtiana) that are longer (20-25 mm long) than those of W. fasciculata (pods also linear in W. fasciculata but much smaller, 14-17 mm long).Wiborgiella bowieana (Benth.)Boatwr.& B.-E.van Wyk, like the new species, also occurs in the Robertson area but differs from W. argentea in the much larger calyx (9.0-10.5 mm long) with long lobes (3.0-3.5 mm long) and the pods that are ovate to lanceolate (calyx 4-5 mm long with the lobes 1.0-1.5 mm long in W. argentea and pods linear).