Sabicea jacfelicis (N. Hallé) Zemagho, O. Lachenaud & Sonké

Zemagho, Lise A., Liede-Schumann, Sigrid, Lachenaud, Olivier, Dessein, Steven & Sonke, Bonaventure, 2017, Taxonomic revision of Sabicea subgenus Anisophyllae (Ixoroideae, Rubiaceae) from Tropical Africa, with four new species, Phytotaxa 293 (1), pp. 448-450 : 448-450

7. Sabicea jacfelicis (N. Hallé) Zemagho, O. Lachenaud & Sonké , comb. & stat. nov. ( Fig. 15 )

Pseudosabicea mildbraedii ( Wernham 1914: 53) N. Hallé var. jacfelicis N. Hallé, Flore du Gabon 12: 208 (1966).

Type :— GABON. km 25 Makokou, piste du Bouéni, 12 February 1961, N. Hallé 1143 (holotype P [P00077589]!; isotypes BR [ BR0000008851987 ]!, K [K000414628]!, P [P00077590]!) .

Scrambling sarmentose woody vine; stems 1.5–5 m long, 1–3 mm thick, densely white-felted and sparsely villose when young, with stiff hairs ca. 1.5 mm long, becoming glabrescent with age. Leaves opposite, strongly unequal, one of them much smaller; smaller leaves sessile, 0.4–2 x 0.3–1.2 cm; larger leaves with petioles 0.5–1.2 cm long, densely white-felted and villose on the upper side when young, with stiff hairs ca. 0.7 mm long; blades narrowly elliptic, 3.3–16 x 1.5–6.5 cm, strongly asymmetrical at base with proximal side round to subcordate and distal side cuneate to round inserted 3–5 mm higher, acuminate at apex, coriaceous, strongly discolorous; upper side green, usually sparsely villose throughout (rarely on the midrib only) with short scabrid stiff hairs 0.5(–1) mm long; lower side whitish, densely felted with woolly hairs, sometimes with sparse stiff hairs 1–1.5 mm long present as well; 10– 16 secondary veins on each side of midrib. Stipules opposite, interpetiolar and connate at base with the petioles into a sheath 2–3 mm long, the free part narrowly triangular, 7–14 x 1–2 mm, entire or shortly 2–3-fid, the lobes, when present, 1–4 mm long, glabrous outside, ciliate on the margin with short woolly and long stiff hairs intermingled, glabrous inside except for long stiff hairs at the base. Inflorescences on old leafless portion of stems or more rarely in the axils of the lower leaves, 1–2 per node, sessile, densely glomerulate, many-flowered, 0.6–1 cm in diameter. Bracts and bracteoles numerous and not clearly distinct from each other, ± hidden between the flowers and not enclosing them, the outer ones elliptic to narrowly triangular, 2.3–3.5 x 0.5–1 mm, acute at apex, the inner ones elliptic, ca. 1.5 x 0.2 mm, glabrous or sparsely felted outside, villose inside near the base with stiff hairs ca. 1 mm long. Flower buds with apex enlarged and ovoid. Flowers 5-merous, heterostylous, subsessile, the minute pedicel (<0.5 mm long) with dense long stiff hairs ca. 1 mm long. Hypanthium glabrous to densely white-felted. Calyx green (probably white outside); tube 0.8–1 mm long, densely white-felted outside, glabrous inside; lobes broadly elliptic to suborbicular, 1–2 x 0.7–1.3 mm, round at apex, densely white-felted outside, glabrous or sparsely villose, with short appressed hairs ca. 0.3 mm long inside. Corolla white; tube cylindrical to slightly funnel-shaped, 4 x 1–1.5 mm; lobes triangular, 1–2 x 0.7–1 mm; corolla glabrous outside, or rarely with a few woolly hairs at lobes apex; mouth and base of lobes densely bearded inside, with white moniliform hairs 0.8–1 mm long; inside of tube either with a ring of trichomes around the insertion of the stamens in short-styled flowers, or villose from the insertion of the stamens to the throat in long-styled flowers. Stamens included, with filaments 0.5–0.8 mm long, inserted slightly above the middle of the tube in long-styled flowers, completely exserted, with filaments of same length and attached just below corolla mouth in short-styled flowers; anthers 1–1.2 x 0.3 mm. Disk cylindrical, ca. 0.5 mm long, glabrous. Style glabrous, exserted, 5.5 mm long in long-styled flowers, included, 4 mm long, almost reaching the corolla mouth in short-styled flowers; stigmatic lobes 0.8–1 mm long, +/- cylindrical, thickened at apex. Fruits pale purplish-white to blackish, obovoid, 7 x 5 mm when fresh, glabrous, subsessile. Seeds pale brown, polygonal, ca. 0.6 x 0.3 mm, the surface with dense parallel striations.

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Distribution: —Lower Guinea Domain. Sabicea jacfelicis occurs in southern Cameroon and north-eastern Gabon ( Fig. 16 ), where it is locally common. It is likely to occur in Equatorial Guinea as well.

Habitat and ecology: —The species is apparently partial to riparian forest edges, at ca. 470 m altitude.

Phenology: —Flowering in March–April, June and October; fruiting in February, April and August.

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Discussion: — Sabicea jacfelicis was originally described as a variety of Sabicea mildbraedii by Hallé (1966), but differs considerably from that species in the taller habit, the inflorescences borne on leafless stems or in the axils of the lower leaves, and the corolla glabrous outside or nearly so (the leaves are also usually narrower, but this character is not absolutely diagnostic). These characters justify its treatment as a species of its own. The ranges of the two taxa are separate, S. jacfelicis being more northern.

Sabicea jacfelicis differs from other lianescent species with inflorescences on the old stems ( S. aurifodinae , S. crystallina , S. ndjoleensis and S. sciaphilantha ) by the shorter calyx lobes and especially by the much shorter corolla tube.

Notes: — Two specimens from Gabon (N. Hallé 2865, Minkébé Series W379) are atypical in having the leaves glabrous above except for the midrib; all other collections show sparse scabrid hairs on the lamina.

Conservation status:— IUCN Red List Category: IUCN Red List Category: Vunerable [VU B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v)]. The extent of occurrence is estimated as 50,672.789 km 2 and the area of occupancy as 40 km 2, the latter value being within the limit for Endangered under criterion B2. The species is known from 10 subpopulations representing 8 locations (sensu IUCN 2012). Two of these locations are potentially threatened by the construction of dams (around Nyabessan in Cameroon, and Makokou in Gabon) and one by a mining project (Bélinga, Gabon). Therefore, a decline in the extent of occurrence, area of occupancy, extent and quality of habitat, number of locations and number of individuals can be projected, and the species qualifies as Vulnerable under conditions B1ab(i,ii,iii,iv,v) and B2ab(i,ii,iii,iv,v).

Additional specimens examined:— CAMEROON. East Province : between Somalomo and Milon, 69 km SE of Akonolinga, 18 June 1981, J.n. Asonganyi 311 ( BR, P, YA); Station du Cacaoyer de N’Koemvone, 14 km on the road from Ebolowa to Ambam, 28 August 1974, J.J.F.E. de Wilde 7442 ( BR, WAG) ; Station du Cacaoyer de N’Koemvone , 14 km on the road from Ebolowa to Ambam, 8 April 1975, J.J.F.E. de Wilde 8155 ( BR, MO, P, WAG, YA); Ambam, bords du Ntem, April 1940, H. Jacques-Félix 5128 ( BR, P, WAG); Somalomo, 17 April 1961, R. Letouzey 3876 ( BR, MO, P); rives de la Biwome près Nyabessan, 8 April 1968, R. Letouzey 9280 ( BR, P, YA); rives du Dja au NE de Sangmélima, près du confluent Lobo – Dja, 25 March 1981, W. Meijer 15247 ( WAG) . GABON. Ivindo National Park , Ivindo River downstream from Ipassa, 9 March 2008, S. Dessein, O. Lachenaud ,

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S. Janssens, Y. Issembe & T. Nzabi 2463 (BR, LBV); Bélinga , 28 October 1964, N. Hallé 2865 (P); Bélinga, 22 June 1966, N. Hallé 3976 (P); Minkébé area, 1°31’N 12°49’E, 18 May 1990, Minkébé Series W 379 ( WAG) .

Figures

FIGURE 15. Sabicea jacfelicis. A, flowering stem; B, detail of a node showing the stipules; C, inflorescence; D, flower bud; E, longstyled flower; F, section of long-styled flower (calyx and ovary removed); G, short-styled flower; H, section of short-styled flower (calyx and ovary removed). From Letouzey 3876 (A), Letouzey 9280 (B–F), de Wilde 8155 (G–H). Drawing by Antonio Fernandez.

FIGURE 16. Distribution of Sabicea jacfelicis.