Psoralea vanberkelae C.H. Stirt., A. Bello & Muasya, 2015

Bello, Abubakar, Stirton, Charles H., Chimphango, Samson B. M. & Muasya, A. Muthama, 2015, Psoralea diturnerae and P. vanberkelae (Psoraleeae, Fabaceae): two new species restricted to the Core Cape Region of South Africa, PhytoKeys 44, pp. 97-107 : 101-104

Psoralea vanberkelae C.H. Stirt., A. Bello & Muasya sp. nov.

Note.

Similar to Psoralea pinnata L., but differs in being a short (less than 1 m) resprouter with sprawling and mounding habit (versus tall reseeder to 5 m with single stem in Psoralea pinnata ); short 5-foliolate leaves (versus 7-9-foliolate); flowers solitary per axil (versus 1-6).

Type.

SOUTH AFRICA. Western Cape, Knysna (-3423), Robberg Coastal Corridor, Fynbos Private Nature Reserve (-AB), 34°05'51.72"S, 23°17'5.82"E, 134 m, 18 October 2013, N. van Berkel 1118 (holotype: BOL!; isotypes: GRA!, K!, NBG!, SCHG!, PRE!).

Description.

Habit a small sprawling and mounding shrub to 60 cm tall and up to 1.5 m wide, resprouter. Stems 1-10, branching in upper parts of stems; branches erect, rough, grey, mostly bare except for upper parts; young seasonal shoots rough, blackish, hairy. Leaves 9 mm long, 10 mm wide, pinnately 5-foliolate, linear oblong, petiolate, fleshy, basal leaves of seasonal shoots smallest, patent to semi-erect, surface bumpy, glabrous; glands raised, hyaline but drying reddish brown to black, rachis grooved; basal leaflet pair 10 mm long, 0.5 mm wide, equal to or slightly shorter than terminal leaflet; terminal leaflet 10-11 mm long, 0.5 mm wide, flat on adaxial surface with a distinct furrow; stipules 2 mm long, 1 mm wide, straight, fused, joined by a bridge of tissue, glabrescent, teeth broadly triangular, apex acute, fleshy, persistent, becoming prominent and woody when leaves are shed, hairy, hairs short and stubby, covered densely with large raised glands. Inflorescences axillary in upper nodes of short seasonal shoots; peduncle short, 2 mm long, hairy; peduncle bracts paired, minute; cupulum 1 mm long, pale green, trifid, shortly triangular, lobes equal, black-haired, covered in large glands, drying reddish brown; pedicel 2 mm long. Flowers 10-11 mm long, pale to intense mauve to blue, borne solitary per axil. Calyx 6 mm long, 4 mm wide; tube 4 mm long, ribbed; teeth equal, shorter than tube, 2 mm long, pale green, sparsely covered in small black flat hairs and densely encrusted with mixed sized glands on outside; margins of teeth densely black ciliate, inside of teeth densely stubby black-haired; vexillar teeth scarcely fused above tube. Standard petal 9-10 mm long, 7-8 mm wide; claw 2-3 mm long, flattened, erect; very broadly ovate, reflexed to 90 degrees, apex rounded; mauve but dark purple in central area above the M-shaped white nectar “guide”, venation purple; callosities above the claw absent. Wing petals 6-7 mm long, 3-4 mm wide; claw 4-5 mm long; longer than keel petals, strongly folded once along middle, slightly billowy near apex, held parallel to keel, strongly auriculate; sculpturing present, upper basal comprised of 4-5 transcostal lamellae. Keel 5-6 mm long, 3-4 mm wide; claw up to 5 mm long. Androecium 7 mm long; tenth stamen free; sheath split abaxially, fenestrate; nectarial ring present, 0.3 mm high. Pistil 7 mm long; ovary 2 mm long, stipitate, glabrous but sparsely covered in curved stalked glands across sides; ovules 1; stigma penicillate. Fruits 1, 5 mm long, 3 mm wide, papery, rugose, reticulate, brown. Seeds 4 mm long, 2.5 mm wide, oblong-elliptic, khaki with black mottles and flecks, hilum central (Fig. 2, Plate 2).

Habitat.

Endemic to South Outeniqua Sandstone Fynbos (FFs19, Rebelo et al. 2006). The vegetation type is a mixture of Eastern Fynbos and Renosterveld. It grows in full sun on sandy soils over Peninsula formation quartzite on a gentle slope. The area was subjected to a controlled burn in April 2008, so plants are becoming old and starting to die back.

Flowering time.

August to November.

Altitude.

70-150 m.

Distribution.

Psoralea vanberkelae is a narrow endemic. It is known from some hundreds of individuals in an area of 500 × 500 m along the George to Knysna coastal stretch of the Indian Ocean and also from Cairnbrogie (Nicky van Berkel pers. comm., photographs) all in Western Cape Province of South Africa (Fig. 3).

Etymology.

The specific epithet vanberkelae honours Ms. Nicky van Berkel, a C.R.E.W. volunteer and iSpotter ( “Nicky”; http://www.ispot.org.za/user/10095), who brought this species to our attention and sent us reference material and photographs. Like many plant enthusiasts from C.R.E.W. she plays a valuable role in establishing the conservation status of plants in her area. The plant is a beautiful flagship species for a very threatened habitat.

Conservation status.

Psoralea vanberkelae is locally abundant in its habitat and the main population is protected by private ownership (Fynbos Private Nature Reserve). It is, however, restricted by a narrow range of distribution (area less than 20 km2). The coastal stretches where the plants occur are all on private land with limited access. The cliff edges rise sharply from the sea and their escarpments are not easy to access. We therefore assess this species to be Vulnerable under the South African Red List categories and criteria (VU D2, von Staden et al. 2009, IUCN 3.1, 2012a, 2012b).

Discussion.

Psoralea vanberkelae is a recent discovery and is part of the Psoralea pinnata complex. It is a small, colonial, resprouting, sprawling and mounding shrub to 60 cm tall and up to 1.5 m wide. It has clasping, tightly packed, 10-11 mm long leaves on short shoots. It also has glabrous leaflets with large round impressed glands. Its terminal leaflet is in most cases longest. It has pale to intense mauve to blue flowers borne at the end of short flowering shoots in pseudo-inflorescences and held above the subtending leaves. Psoralea pinnata on the other hand is a taller much-branched reseeding shrub to small tree up to 5 m tall with 7-9-foliolate linear, 20-45 mm long, villoso-pubescent spreading leaves with the terminal leaflet shortest (Table 1 ).

Additional specimens examined.

Robberg Coastal Corridor, Fynbos Private Nature Reserve Section, Knysna, 34°05'53.84"S, 23°17'4.56"E (3423AB), South Outeniqua Sandstone Fynbos, 134 m, 14 February 2014, A. Bello, C.H. Stirton & A.M. Muasya 53 (BOL).