Vera-Duthiea zebrina

Martínez-Azorín, Mario, Crouch, Neil R. & Crespo, Manuel B., 2018, Vera-duthiea zebrina (Asparagaceae, Scilloideae), a new species from eastern South Africa, and a first genus record for southern Africa, Phytotaxa 375 (4), pp. 283-289 : 285-287

Vera-duthiea zebrina Mart. -Azorín, N.R. Crouch & M.B.Crespo sp. nov. ( Figs. 1 & 2 ).

− Urginea zebrina Oberm. in scheda

It differs from both V. senegalensis and V. macrocarpa in its synanthous rather than hysteranthous phenology, and its filaments that narrow considerably at their base rather than broaden substantially. The leaves of V. zebrina are broadest at the base and are abaxially maculate along their entire length, whereas those of V. macrocarpa are broadest in their middle and spotted only towards the base. Vera-duthiea noctiflora differs by the unspotted, distinctly coiled, proteranthous leaves and its much smaller flowers.

Type: — SOUTH AFRICA. KwaZulu-Natal, Bela Vista (2632 CD): Ndumo [Ndumu] Hill, Ndumo [Ndumu] Game Reserve, 4 November 1968, E. S. Pooley 127 (holotype, NU!, isotype, NH!).

Herbaceous, perennial, bulbous plant. Bulb hypogeal, compact, 5 ‒ 6 × 4.5 ‒ 5 cm, turbinate to subglobose, solitary to occasionally multiplying through division, scales white, thickly succulent, sometimes imbricate; basal plate narrow, to 1 cm in diameter, roots whitish-cream, thickened, contractile, ca. 2 mm in diameter. Leaves 2 ‒ 5(–7), synanthous, bright to mid green, unspotted adaxially and with dark green maculations abaxially that merge to form distinct transverse bands along the entire length, especially prominent at the base, glabrous, narrowly linear, tapering gradually towards an acute apex, deeply canaliculate, rounded abaxially, arching, spreading, 10 ‒ 30 cm long, 4 ‒ 5 mm wide when incurved and 8 ‒ 9 mm wide when flat (broadest at the base). Inflorescence presented above the spreading leaves, racemose, the peduncle erect to leaning, 25 ‒ 38 cm long, greenish-brown, slightly mottled at base, covered with a light white bloom, the raceme lax, 4 ‒ 10 cm long, with 5 ‒ 13 flowers, erect to arching; pedicels of flowers 20 ‒ 30 mm long at anthesis, arching down, purple-brown, with whitish bloom, elongating and arching up in fruit. Bracts very small, ca. 2 mm long, clasping, deltate-triangular, acute, greenish-brown with a membranous white margin, spurs as long as blade, flattened, appressed, those from the middle and upper parts of the inflorescence showing very short or inconspicuous spurs; bracteoles absent. Flowers short-lived, dark brown pentacyclic, trimerous, stellate, nodding, opening in the early evening and closing during night. Tepals 6, biseriate, almost free from the base, outer tepals lanceolate, 13 ‒ 14 × 4.0 ‒ 4.5 mm, with acute apex, inner tepals lanceolate, 13 ‒ 14 × 3.9 ‒ 4.2 mm, with acute apex; tepals adaxially carneous brown with lighter margins and an olive-brown median stripe, carneous brown abaxially with olive-castaneous median stripe. Stamens 6, curved; filaments free, adnate to tepals for ca. 1 mm, incurved along the lower half, almost connivent to style in middle section and spread distally, thickened, terete in cross-section, ca. 10 × 0.7 mm, proximally attenuated in lower ¼ to only 0.3 mm wide; anthers narrowly oblong, carneous, near-basifixed, ca. 3 × 0.8 mm pre dehiscence, dehiscing longitudinally along the whole length. Ovary ovate, greenish above and white at base, shallowly 3-angled, ca. 4.5 × 3.2 mm. Style well differentiated, white, round in cross-section, narrowly clavate, becoming gradually broader distally, deflexed from lower part to distally approach the spreading filaments, ca. 8 × 0.6 mm proximally– 1.1 mm distally. Stigma slightly overtopping anthers, subcapitate, shortly papillate. Immature capsule light cream, basally with conspicuous chestnut markings and green along the septal nectaries, triloculate, loculicidal, ovate, 13–14 × 8–9 mm. Seeds flattened, subelliptic, with prominent central embryo and broad wings, ca. 6.5 × 4 mm, black ( Figs. 1 ‒ 2 ).

Etymology:— zebrina , for the characteristic dark-green banding of the abaxial leaf surfaces.

Biology:—Plants grow as small, often dense clumps which have leaves fully mature when the erect to leaning few-flowered inflorescences are produced. Flowering occurs in early to mid-summer, October through January in southern Africa. The inflorescences present few flowers which last only one night. The flowers open from 17h00 until late into the night; they are strongly scented, emitting a seminiferous or yeasty odour that is presumed to attract moths.

Habitat:—At Ndumo Game Reserve, plants grow in full sun at the edge of pools and pans ( Fig. 1A ) and in seasonally inundated short grassland at an elevation of ca. 35–85 m, on both clay and sandy soils in Western Maputaland Sandy Bushveld (SVl 19) and Western Maputaland Clay Bushveld (SVl 20) within the Savanna Biome (Rutherford et al. 2006). In the Kruger National Park (Mpumalanga Province) plants similarly grow in open moist vlei areas, but at a slightly higher elevation of ca. 240 m.

Distribution:—The new species is known so far only from the northernmost part of KwaZulu-Natal along the Mozambique border, and from Kruger National Park, both sites within South Africa and some 210 km distant ( Fig. 3 ). The likelihood of V. zebrina occurring also in southern Mozambique is high given the proximity of both known localities to borders with that country; the most recent flora checklist for Mozambique ( Da Silva et al. 2004) does not list ‘ D. indica ’. This species may yet be identified from the nearby Kingdom of eSwatini (formerly known as Swaziland).

Taxonomic relationships:—Three species of Vera-duthiea were accepted by Speta (2001, 2016): Vera-duthiea senegalensis , V. macrocarpa and V. noctiflora . The new species clearly differs from all previously accepted species in the genus by the synanthous leaves that are maculated abaxially for their entire length showing a zebrine pattern, whilst the other species present hysteranthous or proteranthous leaves which are only sometimes maculate basally. Moreover, filaments of both V. senegalensis and V. macrocarpa broaden substantially at their base whilst those of V. zebrina narrow distinctly. Vera-duthiea noctiflora is unique in the subfamily in having coiled leaves and produces much smaller flowers than V. zebrina . Further, the four species have disjunct distribution ranges: V. noctiflora is endemic to the arid regions of southwestern Morocco, V. senegalensis is known only from western central Africa, V. macrocarpa (= Ornithogalum laikipiense Newton 2003: 18 ) occurs in East Africa, and V. zebrina is known from the northeastern regions of southern Africa. Other genera closely related to Vera-duthiea are Indurgia , Thuranthos , and Zingela . However, Thuranthos and Zingela show bulbs comprised of loose, cucullate, pedicellate scales, and leaves which are prominently keeled, among other characters, whilst bulbs of Vera-duthiea are compact and their leaves are not distinctly keeled. Members of Indurgia are restricted in range to southwestern Asia, and although superficially similar in flower morphology to Vera-duthiea zebrina , they differ by their unspotted, proteranthous leaves, among other characters.

Additional material studied (paratypes):— SOUTH AFRICA. Mpumalanga: Acornhoek (2431), East of Muntshe Hill, Kruger National Park (- DD), 3 December 1969, line illustration prepared from A. A Mauve 4823 ( PRE!) ; KwaZulu-Natal: Bela Vista (2632), Ndumo Game Reserve near gate area, in seasonally inundated grassland (- CC), elev. 300 ft, 5 November 1969, E. J. Moll 4309 ( NH!, PRE!) ; Bela Vista (2632), Ndumo Game Reserve to southwest of Shokwe Pan on road to Red Cliffs (- CC), elev. 45 m, 16 November 2016 (in flower and immature fruit), N. R. Crouch s.n. (v.v.) ; Bela Vista (2632), Ndumo Game Reserve , alongside road 3.5 km northwest of main gate to reserve (- CC), elev. 40 m, 16 November 2016 (in flower and immature fruit), N. R. Crouch s.n. (v.v.) .

Figures

FIGURE 1. Vera-duthiea zebrina Mart.-Azorín, N.R.Crouch & M.B.Crespo. A. Plant in flower in moist open grassland, Ndumo Game Reserve, KwaZulu-Natal Province, South Africa (Photograph N.R. Crouch); B. Line illustration by R. Collett based on Mauve 4823 (PRE): 1. Bulb and leaves (× 0.5); 2. Raceme (× 0.5); 3. Style and stigma (× 2); 4. Capsule (× 0.5); 5. Seed (× 1).

FIGURE 2. Vera-duthiea zebrina Mart.-Azorín, N.R.Crouch & M.B.Crespo plant in flower in cultivation from Ndumo Game Reserve, KwaZulu Natal Province, South Africa, on 28 June 2018. A. Inflorescence; B. Flower in lateral, apical and dorsal views; C. Dissected flower in lateral view; D. Tepals, outers above and inners below, lateral views; E. Tepals with stamens, dorsal and lateral views; F. Gynoecium and stamens, lateral views; G. Bulb with portion of leaves, lateral view; H. Basal part of leaves and peduncle; J. Details of the canaliculate leaves (left) and apex (right); K. Infructescence; L. Immature capsule, lateral view. Scale bars: 1 cm.

FIGURE 3. Known distribution of Vera-duthiea zebrina Mart.-Azorín, N.R.Crouch & M.B.Crespo in eastern South Africa.