Ceropegia heidukiae D.Styles & Meve, 2021

Styles, David G. A. & Meve, Ulrich, 2021, Ceropegia heidukiae (Apocynaceae-Asclepiadoideae) - a morphologically intriguing and rare novelty from South Africa, Phytotaxa 497 (1), pp. 20-28 : 21

Ceropegia heidukiae D.Styles & Meve , sp. nov. ( Figs. 1 and 2 )

Similar to Ceropegia rudatisii in a subset of vegetative and floral characters such as a cluster of fleshy fusiform roots, erect stems, short petiolate, ovate and glabrous leaves, small lanceolate sepals and longitudinally ribbed corolla tubes with unfused corolla lobe tips, and overall structure of the corona. The flowers of C. heidukiae differ from C. rudatisii in having much longer bracts (15 mm vs. 2–4 mm in C. rudatisii ), shorter pedicels (7–21 mm vs. up to 53 mm), shorter total length (50–65 mm vs. 57–85 mm), a broader corolla tube (10.5–14.5 mm wide at mouth vs. 5–7 mm), shorter spreading corolla lobes (13.5–18.5 mm vs. 27.5–34.5 mm) being broad ovate (vs. narrow lanceolate), strongly projecting (tooth-like) sinuses at base of corolla lobes (lacking in C. rudatisii ), longer staminal corona lobes (4 mm vs. 2–3 mm), and shorter seed coma (45 mm vs. 50–55 mm in C. rudatisii ).

Type: — SOUTH AFRICA. KwaZulu-Natal, Ngome , ca. 1000 m, 06 December 2019, D. G. A . Styles & A . Heiduk 5884 (holotype: NU! [ NU0090688 ]; isotype: BRNH!) .

Perennial erect herbs. Rootstock producing a cluster of fleshy fusiform roots up to 120 mm long and 4.5–7.7 mm thick; latex clear. Stems single, occasionally two from rootstock, rarely branched, annual, green, fleshy, glabrous, to 250–300 mm tall, 4–5 mm in diameter; internodes 18–48 mm long, slightly longitudinally ribbed, distally flattened. Leaves ascending to suberect, shortly petiolate; petiole channelled above, 1–4 mm long, glabrous; lamina ovate to broadly elliptic, 35–47 × 26–35 mm, flatly spread out, slightly fleshy, fairly rigid, base obtuse, apex acute, apiculate, green, glaucous, glabrous, with 5 to 6 lateral nerves. Inflorescences extra-axillary, sessile at youngest node, uniflorous, bracts narrowly linear-lanceolate, ca. 15 mm long; pedicel erect, 7–21 × 1.5 mm, green, fleshy, glabrous. Calyx lobes narrowly lanceolate, 9–17 mm long, ascending, acute, yellowish-green, glabrous, at least half as long as or as corolla tube inflation (ostiolum). Flowers with sweet-acidic scent, anthesis 1–2 days. Corolla upright and straight, 50–65 mm in total length; corolla tube 45–58 mm in total length, longitudinally ribbed with 2 x 5 ribs, five thereof prominent indicating fused petal margins, alternating with five less prominent petal midribs which run all the way up into the corolla lobe tips, outside glabrous and greenish, inside smooth and glabrous, whitish-green with longitudinal purple stripes and similar coloured reticulation on bases of corolla lobe tips; basal inflation (ostiolum) ovoid, 14.5–17 × 7.5–10 mm; median section of tube cylindrical, 13.7–17.4 × 3–3.7 mm; apical section of tube (mouth) funnel-shaped, 10.5–14.5 mm wide, with tooth-like, nearly uncinate lateral protrusions at mouth between transition to corolla lobe bases. Corolla lobes confluent with the tube, 17.6–23.7 mm in total length thereof ca. 1/3 form corolla lobe bases and ca. 2/3 form corolla lobe tips; corolla lobe bases light yellowish-green with olive-green reticulation, glabrous, forming inclined triangular struts, 4–6 mm long, leaving ca. 3 mm wide openings between each other, apically tapering and converging, 1–2 mm at narrowest section, margins gently recurved, with tufts of vibratile trichomes at lobe base upper region, trichomes clavate, pendulous, ca. 1.5 mm long, purplish; corolla lobes ascending to radially spreading into a star-shaped structure (in top view resembling a single radiate flower) arising from the constricted section of the corolla lobe bases, spreading lobe tips ovate, 13.5–18.5 × 7–8.5 mm, with projecting midrib at distal 2/3, then basally indented, abaxially greenish-brown, glabrous, adaxial surface from yellowish-golden green to bronze but always merging into contrasting purple-red towards the converging bases, finally cream-coloured at the centre of the star-shaped structure, densely pilose throughout, trichomes erect, longer at lobe margins and midrib than on area between, up to 0.5 mm long. Gynostegium shortly stipitate, whitish. Gynostegial corona ca. 3 mm in diam., of staminal and interstaminal parts, interstaminal (outer) corona lobes joined to form a shallow cup, adaxial margins purple otherwise white, lobes deeply bifid, lobules ca. 0.7 mm long, small triangular to falcate with the tips spreading, adaxially pilose with spreading translucent-white trichomes ca. 0.4–1 mm long, area below lobules white with a tuft erect, stiff white trichomes ca. 0.3 mm long; staminal (inner) corona lobes erect, linear, ca. 4 × 0.5 mm, parallel to each other with only the tips slightly recurved, basally purple, with some erect trichomes, otherwise white, glabrous. Pollinarium: pollinia broadly ovoid, ca. 400 × 320 µm, yellow, with pointed insertion crest ca. 270 µm long; caudicles ca. 70 µm long; corpusculum roughly obclavate but centrally compressed, ca. 280 × 120 µm, reddish brown. Ovaries narrowly conical, ca. 2.2 × 0.5 mm, glabrous. Follicles with two mericarps developed, erect, linear, 192 mm long and 4.7 mm in diam., glabrous. Seeds ovate-oblong, ca. 9 × 5 mm, with wing ca. 1.5 mm wide, coma ca. 45 mm long, white.

Figures

FIGURE 1. Ceropegia heidukiae from Ngome, KwaZulu-Natal, South Africa. A, Full habit; B, Lateral view of flower; C, Fully-grown, nearly mature follicles; D, E, Close up of corolla lobes showing colour variation; F, Close lateral view of tooth-like protrusions at petal sinuses; G, Grassland habitat at Ngome. Photographs: David Styles.

FIGURE 2. Morphological details of Ceropegia heidukiae flowers.A, Longitudinal section through corolla showing the inner colouration; B, Bract; C, Lateral view of gynostegium and corona (short stipe not visible); D, Top view of gynostegium; E, Pollinarium; F, Cluster of fleshy fusiform roots. Photographs: David Styles (A, B, F) and Annemarie Heiduk (C–E).