A new species of Namaquanula ( Amaryllidaceae : Amaryllideae ) from Namibia with notes on the genus

Namaquanula bruynsii Snijman. a rare species of Amary llidaceae from the Landsberg in southern Namibia described here, is separated from N. bruce-bayeri by plane leaves, the absence of a perigone tube and the lack of a short adaxial hook at the base of each fdament. Shared specialized characters are brittle, tan-coloured bulb tunics and short papillae at the base of each filament. A revised description of Namaquanula D.Miill.-Doblies & U.Miill.-Doblies is given and a key to the gen­ era of Amaryllideae subtribe Strumariinae is provided.


INTRODUCTION
Namaquanula D.Miill.-Doblies& U.Miill.-Doblies, endemic to southern Namibia and the Richtersveld.South Africa, is a genus of small, summer and autumnflowering plants in the family Amaryllidaceae.The genus belongs to the southern African subtribe Strumariinae sensu Meerow & Snijman (2001). in the tribe Amarylli deae.Other genera in the subtribe are Brunsvigia Heist., Crossyne Salisb., Hessea Herb., Nerine Herb., and Strumaria Jacq.(which includes Carpolyza Salisb.), all of which have specialized seeds containing a well-developed.chlorophyllous integument and a stomatose testa.In 2001, while exploring several inselbergs in arid southwestern Africa, Dr P.V. Bruyns found an isolated population of Namaquanula in full flower on Lands berg, a mountain in southern Namibia.This distinct, rare species is described and illustrated here for the first time.Deciduous, bulbous herb.80-130 mm tall in flower, up to 180 mm tall in leaf.Bulb solitary, ovoidal.± 30 mm diam.. covered by several thick, tan-coloured, brit tle tunics; neck slender, up to 30 mm long.Leaves appearing shortly after flowering, 3 or 4, suberect in lower half, spreading to recurved above, narrowly lorate.120-280 x 2.5-4.5 mm.plane, green, glabrous, dying back from apex after maturity, both surfaces alike, outer leaves sheathing at base; cataphyll absent.Inflorescence 12-18-flowered.ultimately subhemispherical, 40-70 mm across; scape erect, 30-65 x 1.5-3.0mm, strongly compressed in cross section, pale green, glabrous, remaining attached to bulb when dry'; spathe valves 2. lanceolate.20-25 x 4-5 mm.membra nous; bracteoles linear, up to 5 mm long: pedicels radi ating, somewhat downwardly curved near ovary at anthesis, becoming straight thereafter, 18-30 x 1 mm, obscurely triangular in cross section, pale green.Perigone actinomorphic.star-shaped, 10-20 mm across, without a tube, pale pink, somewhat hyaline and glistening with a darker pink or greenish median stripe on each tepal.unscented, remaining outspread and turn ing brown when old: tepals 6. free to base, oblong-lance olate.9-12 x 2 mm.spreading to recurved.Stamens 6, prominent; filaments free to base.9-10 mm long, close set at base for 2.5-3.0 mm.otherwise spreading, delicate pink, covered with minute papillae for up to 3 mm on adaxial surface: anthers dorsifixed.± 2 mm long before opening, maroon: pollen whitish.Ovary 3 mm across, trilocular, each locule filled with 1 large ovule; style up to 11 mm long, more or less equalling stamens, slender throughout; nectar collecting around style base: stigma very shortly trifid.Capsule papery, dehiscent, containing 3 seeds at most; seeds ovate.5 mm across, fleshy, pink ish; embryo green.Phenology: Namaquanula bruynsii flowers briefly in January, while the leaves are still dormant.The foliage emerges a few weeks after flowering and becomes fully developed during favourable conditions in autumn.In cultivation the leaves remain green throughout winter but die off from the tips as soon as water is withheld at the end of spring.In nature they probably remain green only as long as conditions remain suitable.

Nam aquanula bruynsii
Diagnostic features: in comparison with other species in the subtribe Strumariinae, the floral morphology of this new species is unspecialized.The flowers are star shaped, regular, and lack a perigone tube, whereas the filaments are free to the base and the anthers are dorsifixed.The only specialized feature is the presence at the base of the filaments of distinct papillae on the adaxial surface.Thus on floral morphology alone the taxonomic position of this new species is readily apparent.
When first described, Namaquanula was recognized as having flowers with a perigone tube, filaments cov ered with papillae and each bearing a short incurved hook near the base of the adaxial surface.Superficially, the star-shaped flowers of Namaquanula resemble those of Hessea and on this basis Snijman (1994) treated Namaquanula as a subgenus of Hessea.However, in a recent molecular phylogenetic analysis using internal tran scribed spacer (ITS) sequences, Hessea and Namaquanula resolved as sister to each other (Weichhardt-Kulessa et al. 2000).Moreover, in an extended phylogenetic analysis of the entire tribe Amaryllideae using morphology and ITS sequences (Meerow & Snijman 2001), Namaquanula resolved as sister to Brunsvigia with Hessea sister to them both.
In assessing the taxonomic position of N. bruynsii, the open, star-shaped flowers, and the absence of both a perigone tube and the inwardly curved hooks at the base of the filaments suggested its possible inclusion in Hessea.The dorsifixed anther attachment, rather than centrifixed to subcentrifixed anthers as in Hessea, and the conspicuous papillae at the base of the filaments, however, also indicated that the species might belong to Namaquanula.Nevertheless, when the bulbs produced leaves, the vegetative characters (the presence of spe cialized, brittle, tan-coloured bulb tunics, 3 or 4 foliage leaves, and the absence of a cataphyll) were typical of Namaquanula.Hessea, in contrast, always has parchment-like bulb tunics, 2 foliage leaves and a subter ranean cataphyll.Although plants of N. bruce-bayeri that have been cultivated in Europe have occasionally pro duced only 1 or 2 leaves per season (Miiller-Doblies & Mliller-Doblies 1985;Weichhardt-Kulessa et al. 2000) the absence of a cataphyll remains constant.
Further support for the placement of this new species in Namaquanula has also come from the molecular phy logenetic analysis of Amaryllideae by Meerow & Snijman (2001).In the results of this study, N. bruynsii (Bruyns 8105) resolved as sister to N. bruce-bayeri (Williamson 3405 NBG), suggesting their shared ances try.
Morphologically N. bruynsii is distinguished from N. bruce-bayeri mainly by its leaves, which are flat in cross section, the absence of a perigone tube, and the lack of short, adaxial hooks at the base of the filaments.In con trast, N. bruce-bayeri has somewhat succulent leaves that are elliptical in cross section, the flower has a 1.8-2.2mm long perigone tube, and each filament bears a short, adaxial hook near the base.
Distribution and habitat: the species is known from a highly localized, small population on the high plateau of Landsberg, southern Namibia (P.V. Bruyns pers.comm.)(Figure 2).The plants grow in somewhat flat patches of granite and quartz gravel in association with wintergrowing succulent plants of the families Aizoaceae, Apocynaceae: Asclepiadoideae, Crassulaceae, and Euphorbiaceae.The specimen Hall 1967 (NBG), com prising a bulb and leaves, collected from Gamochas, ± 60 miles [ 96 km] north of Aus in the quarter-degree grid 2616BA, may represent another population of N. bruyn sii.But until flowering specimens from this locality become available this cannot be confirmed.Etymology: the specific epithet honours Dr P.V. Bruyns whose tireless botanical exploration in southern Africa's arid areas has led to the discovery of this and three other species of Hessea and Strumaria over the past 10 years (Snijman 1999(Snijman , 2005)).