Two new species of Nemesia ( Scrophulariaceae ) from southern Africa

Two new annual species o f Nemesia Vent, are described from southern Africa. N. w illiam sonii is characterized by bright orange flowers with an inflated yellow palate. It differs from the related N. maxii Hiem by having a spur that projects back­ wards, not downwards, and bracts that are lanceolate with a truncate base, not triangular or cordate. It is unusual for the genus in having dimorphic seeds. N. w illiamsonii occurs almost exclusively in the Richtersveld. but has been collected in a few localities across the Orange River in southern Namibia. N. h em ip tera is a delicate, wiry-stemmed annual with small white flowers. The flowers are characterized by a tiny nipple-like spur and a seed that is winged on onlv one side. N. hem ip tera is endemic to the Kamiesberg from near Garies to Kamieskroon.


INTRODUCTION
Nemesia Vent, is a genus o f ± 60 species o f annual and perennial herbs endemic to southern Africa (Steiner 1994).It has been over a hundred years since the last revision of the genus (Hiem 1904) and since that time many new species have come to light (Steiner 1989(Steiner , 1994)).A partial revision for species occurring chiefly in KwaZulu-Natal has been published (Hilliard & Burtt 1986), but there are many new species that need to be described from the Cape Floral Region and southern Namibia, where ± 75 % o f the species occur.The purpose o f this paper is formally to describe two distinctive spe cies, one restricted to Northern Cape and one occurring in the Northern Cape and Namibia.
Fruit set in the type locality was good, but no pollina tors were observed.Related species with similar look ing flowers are pollinated by anthophorid bees (Steiner unpubl.).The spurs o f N. williamsonii do not secrete nectar, but pollen may act as an attractive food source for the pollinators.

This plant was brought to my attention by Dr Graham
Williamson who first encountered it on one of his many excursions into the Richtersveld (Williamson 2000).He showed it originally to Prof. E.A. Schelpe at the Bolus Herbarium at the University of Cape Town, who recognized it as an undescribed species.However, Prof. Schelpe was unable to describe this species before his death and over the years.Dr Williamson made addi tional collections in the hope that someday it would be described.Although it was clear from herbarium material that this species was new. the author described it only after seeing living material in the field.The annotation 'Nemesia marlothii Grant' appears on some specimens of N. williamsonii at NBG and in the literature (Range 1935), but this is a nomen nudum.N em esia hem iptera K.E.Steiner, sp. nov Annual herb up to 310 mm tall; stems rectangular in cross section, com ers ridged, sides up to 0.9 mm wide, minutely glandular pilose, lateral stems up to 250 mm long.Leaves simple, opposite, sessile to shortly petiolate; petioles up to 6 mm long, glandular pilose; lamina ovate to lanceolate, 8-21 x 2 -8 mm, subglabrous to sparsely glan dular puberulous, base rounded to cuneate; apex rounded to acute; margins entire to shallowly dentate.Flowers axillary or in lax terminal racemes, racemes up to 225 mm long; bracts alternate, sessile, lanceolate, lowermost leaf-like, uppermost linear, reduced to ± 2 x 0.3 mm.base truncate, apex acute; margin entire, glandular pubescent; pedicels ± 5 -1 4 mm long, glandular pubescent.Calyx 5lobed, spreading, central upper lobe ± 2 .6 -2 .8x 0.6 mm.lateral upper lobes ± 2.6 x 0.5-0.7 mm, lower two lobes ± 2.2 x 0.6-0.8mm, all lobes narrowly lanceolate, acute, glandular pilose.Corolla bilabiate.6.2-9.6 x 6.7-9.1 mm.upper lip four-lobed.two upper lobes oblong to ovate, 3.2-3.7 x 1.2-2.5 mm.base ± perpendicular to margins, apex rounded to emarginate.two lateral lobes oblong to elliptic, 3.3-4.4x 3.1-3.3mm, base strongly oblique, apex rounded to emarginate; lobes white except for a brown rectangular nectar guide, ± 0.5 x 0.7 mm, below sinus o f upper two lobes; lower lip w ith one lobe, widely obovate and emarginate or obcordate, 3.6-5.7 x 5.0-5.8mm, white, tube below' lip strongly inflated into a convex palate; palate ± 2 .1 x 2.8 mm.white, with dense patch o f capitate, non-glandular trichomes at base o f palate near corolla opening, hypochile ± 2.4 mm long with a raised central ridge, densely pubescent with clavate trichomes; trichomes on distal 2A o f ridge brown, remainder w hite, base o f hypochile draw n out into a short nib-like spur.0.5-0.8mm long, entrance to spur flanked by three brown spots visible on outside o f corolla around base o f spur; inside o f corolla tube white with lilac tinge.widely ovate in outline, 0.6-0.7 x 0.6-0.7 mm, laterally compressed; style ± 0.3-0.4mm, compressed contrary to ovary, apex wider than base, lying between anther pairs, slightly deflexed, stigma a crescent-shaped apical band.Capsules ovate to oblong in outline, ± 3.4-4.6x 3.5-4.5 mm, laterally compressed contrary to septum, apex emarginate to bilobed, lobes acute.Seeds ovate, ± 1.3-2.0x 0.7-1.0mm, verruculate, winged on one side only, wing membranous, pale brown with numerous par allel veins.Flowering time: (July-) August to September (-Decem ber).Figure 3.

Other specimens examined
Diagnostic features: Nemesia hemiptera is easily rec ognized by its small, white flowers with a tiny spur and its seed that is winged on only one side.It can be distin guished from the related N. maxii by its colour (white vs violet), the size o f the corolla < 10 mm long, the smaller spur (< 1 mm vs > 3 mm).
Etymology?: the name refers to its unique, partially winged, seeds.
Distribution and habitat: Nemesia hemiptera is a short lived, wiry-stemmed annual that comes up after winter or early spring showers.It is endemic to Namaqualand and restricted to the Kamiesberg and adjacent rocky hills (Figure 2).It ranges in elevation from about 560 m to 1 250 m.It occurs in sandy, loam soils in Namaqualand Broken Veld, under and around shrubs at the foot o f large granite outcrops.Annual rainfall in this area is probably between 200 and 300 mm. but runoff from the surround ing granite outcrops increases the effective rainfall signi ficantly.The late flowering time for this annual is surpri sing, since the surrounding plants are mostly drying off when these plants flower.Like many annuals from arid areas, the ultimate size o f individuals depends to a large extent on available moisture and nutrients.Flowering is largely dependent on localized rainfall patterns.
Breeding systems: based on cultivated specimens transplanted from the field, Nemesia hemiptera, despite its small flowers, is self-incompatible.In the wild, it is probably pollinated by small pollen-collecting bees (e.g.halictids or allodapines).The spurs do not secrete nectar, but pollen may serve to lure pollinators to the flowers.

Nemesia hemiptera was first collected by Rudolf
Schlechter near Brakdam.± 16 km north o f Garies, on an expedition to Namaqualand that he made with his brother Max in 1897 (Gunn & Codd 1981).Since that time, it has been collected at least a dozen times, but it has never been described formally.