Psoralea nitens (C.H.Stirt. & Muasya) C.H.Stirt.

Stirton CH & Muasya AM. 2017. Ten new species and a new record for the genus Otholobium (Psoraleeae, Leguminosae) from South Africa. Kew Bulletin 72:50. DOI 10.1007/S12225-017-9722-5

Type

Type: South Africa, Western Cape Province, between Krom Rivier Peak and Krom Rivier Dome, Krom Rivier Kloof (3419CA), 10 Oct. 1963, Esterhuysen 30375 (holotype BOL!; isotypes K!, MO!, NBG!).

Morphology General Habit

Erect, densely branched, somewhat cylindrical shrub up to 150 cm tall

Morphology Stem

Stems 1 - many, pubescent, nitid when villous, internodes short

Morphology Leaves

Leaves digitately trifoliolate, petiolate, ascending, aggregated atthe ends ofshortseasonal shoots

Morphology Leaves Leaflets

Leaflets 20 - 30 (- 35) x 3 - 3.5 (- 11) mm; laterals arcuate, asymmetrical, about ⅔ the length of the terminal leaflet; narrowly obovate to obovate, recurved-mucronate, base cuneate, margin finely crenate; surface nitid, densely glandular, glands either sunken or evident only as bumps on the surface, pellucid, drying blackish or reddish brown, glabrous, young leaflets prominently appressed sericeous along midrib and margins; petiole 3.5 – 4 mm long, 2 mm persistent after leaf abscission; petiolules 1 mm long

Morphology Leaves Stipules

Stipules 3 – 5 x 3 mm, longer than petioles, obliquely ovate-lanceolate to triangular, striate, membranous, glan­dular, clasping, pubescent

Morphology Reproductive morphology Inflorescences

Inflorescences in axils of short shoots, pedunculate, pedicellate; peduncle 5 – 7 mm long, comprised of a single triplet of flowers; the triplet subtended by an ovate, 5 x 4 mm, black-haired, glandular bract

Morphology Reproductive morphology Flowers

Flowers 11 - 13 mm long, mauve to dark purple

Morphology Reproductive morphology Flowers Calyx

Calyx lobes unequal, 10 - 12 mm long; much longer than the tube; teeth 6 - 8 mm long; carinal tooth 6 – 7 mm wide, 3- 4 times wider than other teeth; glabrous except for appressed black hairs along the veins and margins. Standard 12 - 13x7- 8 mm, oblong to elliptic, mauve with large purple central nectar guide and veins; scarcely auriculate; claw 2 mm long; apex emarginate, glabrous

Morphology Reproductive morphology Flowers Corolla

Keel petals 6.5 – 7 x 2 mm, claw 2 - 2.5 mm long, apex slightly beaked Wing petals 13 x 3 mm, claw 3 mm long; twice as long and enclosing keel blades; sculpturing upper basal and left central, comprised of up to 20 transcostal lamellae; tips billowy

Morphology Reproductive morphology Flowers Androecium

Androecium 6.5 - 7 mm long, vexillary stamen fused to lower ⅓ of adaxially split sheath, anthers 1 – 2 mm long, equal

Morphology Reproductive morphology Flowers Gynoecium Pistil

Pistil 6 - 7 mm long; ovary1.5 mm long, sparsely glandular; height of curvature 1.5 mm; stigma penicillate

Morphology Reproductive morphology Fruits

Fruits 5x3 mm, papery, reticulate, glabrous

Morphology Reproductive morphology Seeds

Seeds 4 – 5 x 2- 3 mm, chestnut brown, hilum central

Note

Otholobium nitens is related to O. mundianum (Eckl. & Zeyh.) C. H. Stirt. and can be separated from that species by the characteristically numerous dense and variously-sized internal pellucid leaf glands, drying black (vs leaf glands more or less evenly sized, drying reddish orange, sparse),narrower,3- 3.5 (- 11) mm wide leaflets (vs broader, (7 - 11 mm wide leaflets), mauve or bluish purple standard with deep purple nectar guide (vs white standard with green nectar guide), carinal tooth of the calyx black-haired and 3x broader than other teeth (vs carinal tooth white-haired and 2x broader than other teeth), and the wing petals twice as long as the keel petals (vs wing petals one third longer than keel petals). The name Otholobium nitens has been used in Goldblatt & Manning (2000: 502) and Manning & Goldblatt (2012: 569) even though not validly published. The plants growing in the core (Slanghoek, Du Toits Kloof, and Wemmershoek Mountains) area are characterised by the narrowness and shininess of their leaves and the large characteristic keel lobe of the calyx fringed with long black hairs. To the south of these populations there are some isolated colonies in which the flowers are smaller, the keel lobe of the calyx much narrower and the leaves much broader, becoming distinctly obovate. Typical examples include Kerfoot 5523 (Jonkershoek), Esterhuysen 35814 (Franschhoek Mts) and Rycroft 1453 (Kogelberg Peak). These specimens may constitute a distinct taxon but more material needs to be collected as the available material is depauperate. Another atypical specimen is Esterhuysen 29919 . This is a laxer plant with narrower sepals and with leaves intermediate in shape and gland concentration and type. It has the facies ofa hybrid and additional collections are desirable.

Distribution

Africa: South Africa, Western Cape. The greatest concentration of this species occurs in the Slanghoek, Du Toits Kloof, and Wemmershoek Mountains.

Ecology

Mesic mountain fynbos, usually on steep rocky slopes with a southerly aspect at 700 - 1200 m altitude.

Conservation

Otholobium nitens is a rare species and occasional in its occurrence. Under the IUCN Conservation status criteria (IUCN 2001) this species faces no threats but it is a habitat specialist occurring on mountain peaks restricted in the South Western Cape with an extent of occurrence (EOO) below 500 km2 and is therefore Rare (R; von Staden etal.2009). The Rabinowitz Rarity Code is RSN (restricted, sparse, narrow); constantly sparse and geographically restricted in a specific habitat. This species is a resprouter commonly found after fire, but its seed production is sparse.

Phenology

Flowering from late October to late December with a peak in November.