Ceropegia gracilidens Bruyns, 2018

Bruyns, Peter V., Klak, Cornelia & Hanáček, Pavel, 2018, An account of Ceropegia sect. Chamaesiphon (Apocynaceae) in Moçambique with new records and two new species, Phytotaxa 364 (2), pp. 111-135 : 113-115

Ceropegia gracilidens Bruyns , spec. nov. ( Figs 1 , 2)

Differs from Ceropegia floribundior Bruyns in Bruyns et al. (2017: 36) by the single erect stem (in C. floribundior the plant forms a small cluster of short erect to spreading branches), the shallower corolla-tube and the glabrous outer coronal lobes.

Type:— Moçambique, Nampula, 43 km east of Ribaue (1438 DC), ± 600 m, 25 Nov. 2000, Bruyns 8567 (holotype BOL!, isotype MO!).

Perennial geophytic herb 10–30 cm tall, arising from an underground flattened discoid tuber 5–8 cm diam. Stem annual, usually unbranched, erect, 120–300 × 3–4 mm bearing 4–6 pairs of leaves, brownish green, finely pubescent. Leaves ± sessile, narrowly linear, finely pubescent, 100–150 × ± 10 mm, gradually acute. Inflorescences several per stem towards apex alongside nodes, usually 8-flowered, flowers opening ± simultaneously and with strong dunglike odour; peduncle absent; pedicel ± 10 × 1 mm, ascending, finely pubescent; sepals lanceolate, 3–4 × ± 1 mm, finely pubescent. Corolla campanulate to ± rotate, 50–70 mm diam., pale green and finely pubescent outside; tube 2–3 mm deep and very shallowly bowl-shaped, inside glabrous and yellow-green with irregular transverse blackish maroon stripes and bars; lobes ascending to widely spreading, inside glabrous and bright yellow-green, with slightly reflexed margins, narrowly lanceolate-caudate, 25–30 mm long and 8–10 mm broad at base. Corona 2-seriate, ± 7 mm diam., yellow-brown with darker purple-brown spots, glabrous; outer series obscurely cup-like, of five lobes ± 2 mm long laterally fused to inner series, each deeply divided in middle nearly to base into deltate-linear erect and slightly spreading obtuse lobules exceeding height of anthers; inner series of 5 linear obtuse lobules rising from fusion with outer series, pressed to backs of anthers and ± equaling them, ± 1 mm long. Follicles and seeds unknown.

Habitat and Distribution:— Ceropegia gracilidens is known from three collections, all from the northern part of Moçambique and separated by some 450 km. At the southernmost of these (Bruyns 7727), plants grew in a flat patch of shallow soil among scattered trees and shrubs of a robust Xerophyta Jussieu (1789: 50) . Near Ribáué (Bruyns 8567) plants grew in open forest below a low granitic dome with several geophytes. At the northernmost locality (Bruyns 9703) it grew in a small patch of flat, shallow ground among scattered trees at the base of a granitic dome. In each locality around five plants were seen. The more exposed parts of the granitic domes were inhabited by a different vegetation, largely dominated by succulents, especially Aloe , Cynanchum mulanjense Liede & Meve (2012: 753) and C. viminale ( Linnaeus 1753: 452) Linnaeus (1771: 392) , and several spiny species of Euphorbia .

Discussion:—The collection Bruyns 8567 was included under Ceropegia floribundior in Bruyns et al. (2015), to which it was thought to belong. Ceropegia floribundior was described from a single tuber sent to Kew by A. Hyslop from St Faith’s Mission in Zimbabwe, which flowered at Kew in June 1922. Turrill’s species differs from the present new one by the deeper tube in the corolla (7 mm long and bell-shaped opposed to 2–3 mm deep and shallowly bowl-shaped here) and by the pubescence on the outer coronal lobes (the whole gynostegium being glabrous here). Vegetatively they also differ, with C. floribundior producing 2–3 stems to 6 (10) cm long from the growth-point on the tuber while in the present new species each tuber usually develops only one stem that is taller, regularly reaching 15–30 cm. From C. floribundior var. mlimakito ( Masinde 2007: 64) Bruyns in Bruyns et al. (2017: 36) ( Masinde, 2007) the new species differs by flowering with fully developed leaves (flowering before the leaves are developed in var. mlimakito ), having much larger flowers 50–70 mm diam, with lobes 25–30 × 8–10 mm (no diameter given but lobes 10–13 × 2–3 mm in var. mlimakito ) and a broader, flatter gynostegium (± 7 mm diam., opposed to ± 4 mm diam. in var. mlimakito ).

Our results ( Bruyns et al. 2015) showed that C. gracilidens falls (with C. buchananii and C. cyperfolia ) among a group of large-flowered species that is widely distributed in tropical Africa from Kenya in East Africa to Nigeria in West Africa, the ‘large-flowered tropical group’ ( Bruyns et al. 2015: fig. 1).

Figures

FIGURE 1. Ceropegia gracilidens. A, side view of centre of dissected flower (scale 5 mm); B, C, side view of gynostegium (scale 2 mm, at C); D, pollinarium (scale 0.25 mm). Drawn from:A, B, D, Bruyns 8567 (BOL, MO); C, Bruyns 9703 (BOL).