Heliophila verna Al-Shehbaz, 2022

Al-Shehbaz, Ihsan A., Mandáková, Terezie, Mummenhoff, Klaus & Lysak, Martin A., 2022, Heliophila verna (Brassicaceae), a new species from the Northern Cape of South Africa, Phytotaxa 555 (2), pp. 195-199 : 195-199

Heliophila verna Al-Shehbaz , sp. nov.

Diagnosis:— Heliophila verna is readily distinguished from the other glabrous annual congeners with filiform leaves and submoniliform terete fruit by having fruiting pedicels 2–3 mm long, smallest flowers (petals to 1.5 mm long), slender and cylindrical styles 0.2–0.3 mm wide, and 14–18 ovules per ovary.

Type: — SOUTH AFRICA. Northern Cape, Namakwa District, Kamiesberg, Verbe Farm , Lat. -30.074167; Long. 18.003056, 760 m, 4 October 2019, T. Mandáková, M. A. Lysak & K. Mummenhoff s.n. (holotype, MO-6942172). Figures 1–3 .

Description: —Plants annual herbs, not glaucous, glabrous. Trichomes absent. Stems herbaceous, 2.5–7 cm tall, smooth, terete, erect, simple or rarely1-branched above. Leaves cauline, subfleshy; petiole absent; blade simple, filiform, 1.5–2.7 cm × 0.3–0.5 mm, margin, entire, not auriculate at base, without a pair of stipule-like glands at node, glabrous, base not decurrent. Racemes terminal, lax, 7–11-flowered, elongated in fruit, not secund; rachis straight, glabrous; fruiting pedicels without a pair of basal bract-like glands, not articulate at base, glabrous, slender and narrower than fruit, ascending, straight, persistent, lowermost 2–3 mm long; flower buds oblong. Sepals suberect, oblong, 1.5–1.7 mm long, glabrous, caducous, both pairs not cucullate at apex, not saccate at base. Petals white, oblong-obovate, 1.4–1.5 × 0.7–0.8 mm, erect, obtuse at apex, unappendaged, not papillate; claw absent. Stamens erect, subtetradynamous; filaments 0.5–0.6 mm long, glabrous at base, all unappendaged; anthers ovate, ca. 0.3 mm long, not apiculate at apex. Nectar glands lateral, minute, median glands absent. Ovary glabrous; ovules 14–18 per ovary. Fruit dehiscent silique, capsular, linear, excluding style 1.5–2.3 cm × 0.7–0.9 mm, terete, glabrous, submoniliform, undulate along replum, subtorulose, ascending; valves papery, midvein distinct, lateral veins obscure, margin not thickened; gynophore obsolete; style in fruit 2.2–3.5 mm long, cylindrical, slender, 0.2–0.3 mm wide, glabrous; stigma entire. Seeds uniseriate, ovoid, plump, wingless, not margined, 0.7–0.8 × 0.5–0.55 mm; cotyledons diplecolobal. 2 n = 18.

Phenology: —Flowering and fruiting late September into October.

Distribution: —Known only from the type collection in Kamiesberg of the Northern Cape.

Discussion: — Heliophila verna can easily be confused with H. namaquana Bolus (1896: 16) , another diploid with 2 n = 18 ( Mandáková et al., 2015). The close relationship of the two species is supported by phylogenetic analysis based on nuclear ribosomal DNA internal transcribed spacers (ITS-rDNA; unpublished data) (in prep.). Both species are annuals with narrowly linear to filiform, undivided, subfleshy to fleshy leaves, short fruiting pedicels generally <4 mm long, submoniliform fruit with undulate replum, and uniseriate seeds. Although both species grow in Kamiesberg of the Northern Cape, the latter is also widespread in the Western Cape. H. verna is easily distinguished from H. namaquana in having rather slender (vs. stout) fruiting pedicels, slender and cylindrical styles 0.2–0.3 mm wide (vs. stout and globose, ovoid, clavate, or cylindrical-clavate styles (0.6−) 0.9−2.5 mm wide), fruit 0.7–0.9 (vs. 1–2.2) mm wide, and smaller flowers with sepals 1.5–1.7 (vs. 2.2–4) mm long, petals 1.4–1.5 × 0.7–0.8 mm (vs. (3–)3.5–5.5 × 1.5–2.5 mm) without claw (vs. with claw 0.5–1 mm long), and filaments 0.5–0.6 (vs. 2–3.5) mm long. Furthermore, plants of H. verna are always glabrous, not glaucous, and lack the stipule-like leaf basal glands and petal appendages. By contrast, plants of H. namaquana are puberulent, pubescent, or glabrous, always glaucous, and the foliar stipulelike glands and petal appendage may be present or absent.

Figures

FIGURE 1. Heliophila verna. A. Plant. B. Sepal. C. Petal. D. Fruit and fruiting pedicel. E. Seed. Drawn by Al-Shehbaz from the holotype (Mandáková et al. s.n., MO-6942172).

FIGURE 2. Heliophila verna. Image of holotype (Mandáková et al. s.n., MO-6942172).

FIGURE 3. Heliophila verna. A. Plant. B. Mitotic chromosome spread. Scale, 10 µm. C and D. Photos of the type locality in Kamieberg of the Northern Cape. Arrows indicates the exact collection site. (Photos by T.M.).