Psoralea papillosa C. H. Stirt. & Muasya, 2024

Stirton, Charles H., Bello, Abubakar & Muasya, A. Muthama, 2024, Ten new species and notes on the genus Psoralea L. (Psoraleeae, Fabaceae) from South Africa, Plant Ecology and Evolution 157 (3), pp. 291-312 : 291-312

2. Psoralea papillosa C. H. Stirt. & Muasya sp. nov.

Figs 2 , 3

Psoralea sp. 28 (“ Psoralea papillosa C. H. Stirt. ms. ”, nom. nud.), Stirton and Schutte (2012: 575)

Type.

SOUTH AFRICA – Western Cape Province: 3320 (Montagu) • Kogmanskloof, Legoland climbing area ; 33 ° 48 ’ 49.55 ” S, 20 ° 5 ’ 29.79 ” E; 25 Jul. 2012; Gwynne-Evans 6988; holotype: BOL; isotypes: NBG, PRE .

Diagnosis.

Species similar to Psoralea kougaensis C. H. Stirt, Muasya & A. Bello from which it differs in its hemispherical habit ( P. kougaensis erect columnar habit), seasonal shoots bright yellowish green, glabrous ( P. kougaensis greenish-black, bristly pubescent), terminal and lateral leaflets about equal, basal pair longest ( P. kougaensis terminal leaflet shorter than lateral leaflets), flowers 1–2 per axil, 9–10 mm long ( P. kougaensis 3–5 per axil, 12–15 mm long), peduncle absent ( P. kougaensis stout and rigid), cupulum bilobed ( P. kougaensis trilobed) with abaxial pair deeply cleft, appearing trilobed; standard petal broadly elliptic, white, with a 2 mm wide violet purple nectar patch above the vertical scarcely swollen callosities ( P. kougaensis standard petal very broadly ovate, dark mauve fading towards the margins and with a large broadly triangular central nectar patch above the swollen callosities from which arises a vertical purple flash tapering to the apex), and calyx teeth glabrous, subequal, carinal lobe slightly longer but narrower than the rest ( P. kougaensis equal, glabrous to sparsely pubescent with carinal lobe slightly wider and less hairy than rest).

Description.

Rounded shrubs up to 1.5 m tall; resprouter. Stems 2–4, branching from lower parts, semi-erect to arcuate, brown with scattered semi-storied lenticels; young seasonal shoots bright green, glabrous. Leaves 5 (– 7) - foliolate, petiolate, terminal and lateral leaflets about equal, 24–25 × 0.5 mm, mid-pair 5 mm shorter; basal leaves of seasonal shoots somewhat larger, 30 × 0.7 mm; furrowed on adaxial surface, surface papillose, margins irregular. Stipules 2–2.5 × 0.6–1.0 mm, fused to base of petiole, glabrous, apex acute, subulate-triangular, recurving, becoming woody when old, 1–2 - veined, densely glandular, tightly recurved, sides reflexed. Inflorescences axillary to upper nodes of short seasonal shoots; peduncle absent. Flowers 1–2 per axil, 9–10 mm long, basal bracts paired, free, minute; cupulum 1.5 mm long, bilobed with abaxial pair deeply cleft, appearing trilobed, covering base of calyx, lobes equal, patent, acuminate, adaxial lobe broadest, sparsely black-haired, minutely glandular, 1 - veined; pedicel 3.5 mm long, glabrous, glandular. Calyx lobes 5.0–5.5 × 2–4 mm; teeth subequal, 3 mm long, outside glabrous, inside black-haired in sinuses and midrib area; tube 4 mm long, not distinctly ribbed, carinal lobe slightly longer but narrower than the rest. Standard petals 7 × 6 mm; claw 1.7 mm long, narrow, incurved; white, broadly elliptic, reflexed to 90 °; with a 2 mm wide violet purple nectar patch above the vertical scarcely swollen callosities; apex apiculate. Wing petals 11 × 4 mm, claw 3–4 mm long; longer than keel petals, strongly folded along the middle; auricle well-developed, swollen and anastomosing; sculpturing present along the top groove, upper basal, comprising up to 7 curving transcostal lamellae. Keel petals 10 × 3 mm, claw up to 4 mm long, apex acute. Androecium 10 mm long; tenth stamen free, sheath split adaxially, fenestrate. Pistil 10 mm long, ovary 1.5 mm long, sessile, glabrous; height of curvature 4 mm, thickest at point of flexure, stigma capitate. Fruits and seeds unknown.

Distribution and habitat.

Endemic to South Africa (Fig. 2 ). So far known only from three collections between 203 and 210 m a. s. l. on the ecotone of Robertson Succulent Karoo (SKv 7) and South Langeberg Sandstone Fynbos (FFs 16) ( Mucina and Rutherford 2006) and from two sightings on iNaturalist. The hinterland of this species is poorly explored so it can be expected to occur more widely.

Phenology and ecology.

Little is known about the ecology of this distinctive species. Flowering occurs in July.

Etymology.

The specific epithet papillosa (Latin ‘ papilla’ = nipple) refers to the single row of small, raised glands on the upper surface of the leaflets on either side of the abaxial groove of the leaflet.

Preliminary IUCN conservation assessment.

Still too poorly known to make an assessment, therefore warranting Data Deficient (DD). The hinterland of its known occurrence, particularly the arid fynbos habitats in the Little Karoo, is still not well explored.

Additional material examined.

SOUTH AFRICA – Western Cape Province: 3320 (Montagu) • Kogmanskloof, Legoland climbing area , (– CC); 15 Jul. 2019; du Preez 675; https://www.inaturalist.org/observations/39443551 ; BOL .

Observation.

South Africa, Western Cape Province: Montagu, Kogmanskloof, 33 ° 48 ’ 48.52 ” S, 20 ° 05 ’ 32.6 ” E, 15 Jul. 2019, obs. by Marion Mclean, https://www.inaturalist.org/observations/36911558.

Figures

Figure 2. Known distribution of the ten described Psoralea species. Map by Abubakar Bello.

Figure 3. Psoralea papillosa. A. Habitat. B. Habit. C. Bark of old stem. D. 7 - foliolate leaflet. E. Fruiting calyces. F. Leaflet showing the marginal papillate glands. G. Calyx opened out. H. Section of shoot showing recurved stipules. I. Side view of a flower. J. 1 - flowered axillary inflorescences. Photographs: A, D – H by Brian du Preez; B, I by David Gwynne-Evans.