Afrohybanthus Flicker, 2015

Flicker, Benjamin J. & Ballard, Harvey E., 2015, Afrohybanthus (Violaceae), a new genus for a distinctive and widely distributed Old World hybanthoid lineage, Phytotaxa 230 (1), pp. 39-53 : 43-44

Afrohybanthus Flicker gen. nov.

Diagnosis. The new genus is similar to southern Australian taxa in the Old World Hybanthus caledonicus group and many New World taxa, but divergent from Hybanthus sensu stricto in having solitary flowers, strongly zygomorphic corollas with a well differentiated bottom petal, filaments basally connate into a short “collar” with free portions to the filaments, two staminal glands, and 3–5 seeds per capsule valve. It shares with the Hybanthus caledonicus group a short but distinct spur at the base of the bottom petal, rather than a merely saccate or distended bottom petal characteristic of most New World taxa including Hybanthus sensu stricto. It is different from the Hybanthus caledonicus group in the elongate glands with medial or upper attachment on the filaments, and is unique in producing ellipsoid to narrowly ovoid, pale yellow or honey-colored seeds commonly with longitudinal ribs and/or foveolae in several to many lines.

Description. Herbs, subshrubs, occasionally shrubs 10 cm to 3 m. tall, stems glabrous to scarcely pubescent, occasionally densely pubescent. Leaves simple, alternate, occasionally fascicled, sessile to subsessile, linear to obovate, 0.5–8 cm long, 0.1–1.8 cm wide, base cuneate, lamina herbaceous to chartaceous, veins reticulate, margins entire to denticulate, occasionally with violoid gland on teeth and at apex, glabrous or pubescent, stipules persistent to deciduous, linear to lanceolate, apex acute, occasionally glandular tipped, 1.5–6 mm long, membranous to herbaceous, glabrous to sparsely pubescent, ciliate along the margins. Inflorescences of axillary solitary flowers, peduncles 2–8 mm long, glabrous to pubescent, peduncle bracts subopposite, positioned in the apical half to third near articulation point, membranous, lanceolate, usually glandular tipped, glabrous to pubescent, up to 3 mm long, summit ending at articulation between peduncle and pedicel. Flowers borne on a pedicel (from articulation to base of flower) 5–30 mm long, glabrous to pubescent, 6–25 mm long, sepals 5, herbaceous, subequal, 2.5–4 mm long, pubescent along costa, occasionally ciliate along the entire margins, 3–7-nerved, upper 3 lanceolate, bottom 2 falcate-lanceolate, all with apex acute. Corolla strongly zygomorphic, petals white, yellow, pink or purple, herbaceous, glabrous, upper pair lance-ovate, 3–6 mm long, rarely exceeding the calyx, 3–5 nerved, lateral pair falcate, 4–7 mm long, slightly exceeding the calyx, 7–9- nerved, basal petal spurred, strongly clawed, with large blade exceeding the calyx, spatulate to orbicular, apex obtuse occasionally cuspidate or retuse, 8–20 mm long, 2–6 mm wide, often marked with a honey guide. Filaments 1.5–2.5 mm long, connate at base into a minute “collar” less than 1 mm long, free portion above filament tube about 1 mm long, the bottom pair of stamens each with a nectary gland attached medially or in the upper third of the free portion of the filament, glands petioled up to 1 mm long, occasionally sessile, glands usually with a tuft of hairs. Anthers 1.5–4 mm, glabrous, the bottom 2 occasionally with long hairs along the costa of the anther connective, dorsal connective scales short, ovate, glabrous, margin entire, apex rounded. Ovary globose, 1.1–2 mm long, 0.7–1.1 mm wide, glabrous, rarely densely short-pubescent. Style slightly exceeding the anthers, up to 4 mm long, thickened at the tip. Fruit a three-valved capsule, glabrous, rarely short-pubescent, straw-colored at maturity, occasionally pale green, 4–9 mm long. Seeds typically 9, 12 or 15 (3–5 per valve), rarely 6 or 18, pale yellow or honey-colored, typically ribbed and/or foveolate longitudinally in several to many lines, very rarely smooth, narrowly ovoid to ellipsoid, glabrous, 1.2–2.1 mm long, 0.6–1.8 mm wide. Chromosome numbers based on x = 8.

Type species: Viola enneasperma L.

Etymology: —The name is based on a combination of the regional center of taxonomic diversity for the H. enneaspermus group (Africa) and the broadly defined genus to which this and other hybanthoid lineages have previously been allied.