Ceropegia pseudorhynchantha Bruyns, 2020

Bruyns, Peter V., Klak, Cornelia, Mazuch, Tomáš, Gelle, Faysal Jama, Elmi, Hassan Sh Abdirahman & Hanáček, Pavel, 2020, New species of Ceropegia (Apocynaceae) from the Horn of Africa, Phytotaxa 441 (2), pp. 195-202 : 199-201

Ceropegia pseudorhynchantha Bruyns , spec. nov.

Type:— ETHIOPIA. Sidamo Region, 60 km SE of Negele on track to Welensu ranch, 1350 m, May 1982, Friis et al. 2751 (holotype ETH!,, isotype K!). Figs 1 , 4 .

This new species differs from C. somalensis Chiovenda (1916: 427) by the shorter corolla-tube with proportionally much longer basal inflation, the tube only slightly widening towards its mouth and by the lack of fine hairs on the outside of the tube.

Slender climbing succulent perennial arising from cluster of swollen fusiform roots. Stem usually solitary from rootstock, slightly fleshy, climbing to 1–2 m, 2–4 mm thick, twining and sometimes branching above, glabrous, grey-green; leaves 20–40 × 12–20 mm, ovate to ovate-lanceolate, acute, flat, not fleshy, glabrous except for fine marginal hairs, green, with petiole 8–12 mm long. Inflorescence glabrous, bearing several flowers in gradual succession on slender spreading peduncle 10–25 mm long with several small bracts at apex; pedicel 5–8 × ± 1 mm, grey-green, ascending; sepals 1.5–2.5 mm long, 1 mm broad at base. Corolla 28–33 mm long, tubular with lobes remaining fused at tips and twisted together in slender column above tube; outside pale green, glabrous and finely papillate; inside tube with prominent maroon lines on pale green and glabrous in basal inflation, above basal inflation with red lines and fine paler hairs, on lobes pale green along midrib (brownish near base) and rest white with irregular red veins, with short cilia ± 0.5 mm long on margins of lobes and longer hairs ± 1.5 mm long along midrib near mouth of tube; tube ± 16 mm long, with ovoid basal inflation ± 10 × 7 mm, narrowing to 3 mm diam. then widening gradually to ± 5 mm at mouth; lobes ± 17 mm long, folded longitudinally for lower 4 mm where ± 4 mm broad then narrowing to ± 0.25 mm broad and gradually widening to 0.5 mm broad at tips. Corona ± 2.5 × 3 mm, with slight basal stipe; outer lobes <1 mm tall, spreading to form broad bays around guide-rails, notched in middle to half of height into two obtuse lobules, translucent with dark purple-black margins and yellow patches inside this, with many straight white hairs <1 mm long inside; inner lobes ± 1.7 mm long, ± 0.5 mm broad above middle, adpressed to backs of anthers then rising together in column over centre of gynostegium, yellow in upper third then pale red below, obtuse, glabrous. Follicles and seed unknown.

Distribution & Habitat:—This species is known in southern Ethiopia in Harerghe near Babile and in Bale around Sof Omar and further south in Sidamo along the track from Negele southwards to Welensu. It occurs at altitudes of 1300–1600 m, with rainfall probably between 400 and 600 mm annually, falling mainly in summer.

In both areas in the Bale region it occurs on stony flat areas with shallow soils overlaying limestone. In the second area the vegetation consists of scattered trees, with a uniform cover of other shrubs around 1 m tall and with many other small succulents, mainly growing under these shrubs. The very inconspicuous C. pseudorhynchantha climbs into these other shrubs.

Discussion:—On account of its swollen roots, slightly fleshy cylindrical stem, deciduous non-succulent leaves that are a slightly paler green than the stem and the broadly basin-like outer corona with relatively low, bifid, pubescent lobes, this species belongs to sect. Phalaena Huber (1957: 30) . Analyses of molecular data also placed it there, where it was annotated as ‘ C. rhynchantha Ethiopia’ in Bruyns et al. 2015: fig. 1.

This new species was initially thought to belong to Ceropegia rhynchantha Schlechter (1913: 155) which occurs in West Africa. This was because of the similarly slender flowers, slight basal inflation and the only slight expansion of the tube towards the mouth, as well as the relatively long, narrow lobes. It was listed as an unnamed species that is similar to C. rhynchantha by Gilbert (2003: 164). However, molecular data showed that it is more closely allied to C. affinis Vatke (1876: 218) and C. somalensis ( Bruyns et al., 2015: fig. 1), which also occur in Ethiopia and in other parts of North-east Africa. It differs from C. somalensis in the considerably smaller flower (this is 35–44 mm long in C. somalensis ) which is not pubescent outside (finely pubescent outside in C. somalensis ) and has a shorter and less constricted tube, more of which is taken up by the basal inflation (the basal inflation is much smaller relative to the length of the tube and of the flower as a whole in C. somalensis , as shown in Bruyns 1989: fig. 6) and the only slight widening of the tube towards its mouth (while the tube more than doubles its diameter towards the mouth in C. somalensis ). The shape of the corolla is different from that in C. affinis , which lacks the long extensions to the lobes. In C. affinis the lobes are short, rising up briefly above the tube to become nearly horizontally incumbent over it in a small, globose cage. In C. affinis the gynostegium is raised on a pedestal above the base of the tube, which is lacking in C. pseudorhynchantha .

Ceropegia rhynchantha also belongs to Sect. Phalaena ( Bruyns et al., 2017) but it is more distantly related to our new species ( Bruyns et al., 2015). In C. rhynchantha the corolla is similar in shape, but the tube is slightly longer above the basal inflation (± 13 mm long as opposed to around 6 mm long in C. pseudorhynchantha ). Ceropegia rhynchantha also differs in habit. Many plants have shoots spreading horizontally on the ground from the rootstock and the shoots only ascend and twine slightly when they are about to flower. It usually occurs in shallow pockets of soil on large granitic outcrops and boulders, with the shoots forming runners between adjacent pockets of soil on these rocks and readily rooting when a new pocket of soil is reached.

Additional specimens examined:

ETHIOPIA. Harerghe Region, Gursum, west side of Daketa Valley, 5.5. km east of Babile, 1500–1600 m, May 1993, Kuchar & Kidar 19075 (ETH!). Bale Region, Sof Omar, near Ghinir, 1400 m, May 1982, Friis et al. 3679 (K!). Sidamo Region, 60 km SE of Negele on track to Welensu ranch, 1350 m, May 1982, Friis et al. 2751 (ETH!, K!). 28 km towards Welensu ranch, 1370 m, Nov. 2009, Bruyns 11584 (BOL!, E!, MO!).

Figures

FIGURE 1. A, B, Ceropegia buraoensis. A, branch with flower. The rearward-pointing bases of the leaf-rudiments can clearly be seen here. B, branch showing rear of corolla. C, Ceropegia marronina, Bruyns 13247 (BOL), D, Ceropegia pseudorhynchantha, Bruyns 11584 (BOL, E. MO). Photographs by:A, B, T. Masuch. C, D, P.V. Bruyns.

FIGURE 4. Ceropegia pseudorhynchantha. A, plant greatly reduced in length (scale 10 mm). B, bud (scale 3 mm). C, side view of flower (scale 3 mm, as for E). D, corolla-lobe (scale 2 mm). E, side view of base of dissected flower. F, side view of gynostegium (scale 1 mm). G, face view of gynostegium (scale 1 mm). H, pollinarium (scale 0.25 mm). Drawn from Friis et al. 3679 (K) by P.V. Bruyns.