Sabicea aurifodinae (N. Hallé) Razafimandimbison, B. Bremer, Liede & S.A.Khan

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

2. Sabicea aurifodinae (N. Hallé) Razafimandimbison, B. Bremer, Liede & S.A.Khan (in Khan et al. 2008: 14)

( Fig. 9 )

Pseudosabicea aurifodinae N. Hallé (1966: 201) .

Type :— GABON. Moubigou 2, au bout de la route de Massima vers Moumba, 21 May 1963, N. Hallé & G. Cours 6137 (holotype P [P00077578]!; isotypes BR!, K [K000414633]!, P [P00077579, P00077580]!) .

Sarmentose woody vine; stems up to 3 m long, 2–10 mm thick, rooting at base, glabrous or with very sparse woolly hairs near the apex. Leaves opposite, strongly unequal, one of them much reduced; smaller leaves subsessile, blades 0.4–0.6 x 0.15–0.3 cm; normal-sized leaves with petioles 0.5–2.5 cm long, glabrous or sparsely villose, with stiff hairs 1–1.5 mm long; blades elliptic, 11.7–29 x 5–15.7 cm, asymmetrical at base with proximal side obtuse to subcordate and distal side cuneate inserted 2–10 mm higher, acuminate at apex, papery to slightly coriaceous, strongly discolorous; upper side green, glabrous or with sparse stiff hairs 2–2.5 mm long; lower side white to buff, densely felted with woolly hairs (sparser on veins); secondary veins 12–21 on each side of midrib. Stipules opposite, interpetiolar and connate at base with the petioles into a sheath 3–8 mm long, the free part elliptic to narrowly triangular, 9–17 x 2.5–3 mm, acute at apex, erect to patent, glabrous or with very sparse woolly hairs outside, glabrous inside except the basal part with stiff hairs ca. 1.5 mm long. Inflorescences on older leafless, basal portion of stems, near the ground, 1–2 per node, sessile and densely glomerulate, many-flowered, 1.3–3.5 cm in diameter. Bracts and bracteoles not clearly distinct from each other, ± hidden between the flowers or the lower ones partly surrounding them in the young stage, the outer ones broadly ovate, concave and +/- spathaceous, 3–6.5 x 2.5–3 mm, the inner ones narrower, 5–6 x 1.2–1.8 mm, glabrous or sparsely felted outside, densely villose inside on the whole surface with soft silky hairs ca. 1.2 mm long. Flower buds with apex ovoid and slightly enlarged. Flowers 5-merous, subsessile, heterostylous. Hypanthium glabrous or sparsely felted. Calyx with purplish tube and white lobes; tube 1–2 mm long, glabrous or with short woolly hairs outside, glabrous inside; lobes narrowly triangular and gradually narrowed to an acute apex, thin, flat or faintly canaliculate, erect or

18 • Phytotaxa 293 (1) © 2017 Magnolia Press

ZEMAGHO ET AL. TAXONOMIC REVISION OF SABICEA SUBGENUS ANISOPHYLLAE

Phytotaxa 293 (1) © 2017 Magnolia Press • 19 slightly bending outwards at apex, 3.5–5 x 0.5–0.7 mm, glabrous or sparsely felted outside, villose with short appressed hairs or rarely glabrescent inside. Corolla white; tube narrow and almost cylindrical, 8.5–11 x 1–1.5 mm long; lobes triangular, ca. 2 x 1.3 mm; outside of corolla glabrous to densely felted on the lobes and upper part of tube, the apex of the lobes sometimes with additional silky hairs ca. 1 mm long; mouth and base of lobes inside densely bearded with ca. 1 mm long white moniliform hairs; inside of tube with a ring of hairs around mid-height, and either villose from the mouth down to the insertion of the stamens in long-styled flowers, or glabrous at the distal portion in short-styled flowers. Stamens either half-exserted, on filaments ca. 1 mm long attached ca. 1.5 mm below mouth in long-styled flowers, fully exserted in short-styled flowers; anthers ca. 1.2–2 x 0.5 mm long. Disk cylindrical, ca. 0.2 mm long, glabrous. Style glabrous, either ca. 10 mm long, exserted in long-styled flowers, ca. 9 mm long, included in short-styled flowers; stigmatic lobes ca. 1.5 mm long, narrowly elliptic. Fruit green (probably not mature), obovoid, 10 x 15 mm when fresh, 6–11 x 4–6 mm when dry, glabrous or with short and very sparse woolly hairs. Seeds pale brown, polygonal, ca. 0.6 x 0.3 mm, the surface with dense faint parallel striations.

unique to one of the species are in bold.

20 • Phytotaxa 293 (1) © 2017 Magnolia Press

ZEMAGHO ET AL.

Distribution: —Lower Guinea Domain. S. aurifodinae is apparently endemic to southwest Gabon, where it occurs in the Doudou Mts and the western part of the Chaillu massif ( Fig. 8 ). It might be expected in the Republic of Congo.

Habit and ecology: —Forest edges in half-shade, particularly along roads; at 140–650 m altitude.

Phenology: —Flowers in May and October: fruits (probably not mature) in April–May and November.

Discussion: — Sabicea aurifodinae is similar to S. crystallina , S. ndjoleensis and S. sciaphilantha . All these species are robust, sarmentose, woody vines, with leaves in strongly unequal pairs, stipules entire, corolla tube long, and inflorescences mostly on the older, basal portion of stems (below the leafy nodes). The differences between them are given in Table 3.

The species is here regarded as monotypic, as we consider Pseudosabicea aurifodinae var. crystallina N. Hallé (1971: 316) to represent a separate species, Sabicea crystallina . Part of the material cited under P. aurifodinae in the Checklist of Gabonese Vascular Plants ( Sosef et al. 2006) belongs to either Sabicea crystallina (A.M. Louis 116, G. Walters 505 & G. Walters 553) or S. sciaphilantha (F.J. Breteler 14850, F. Hallé 4537, D.W. Thomas 6460).

Hallé (1966) described the calyx of S. aurifodinae as glabrous and used this character in his key to the species. The indumentum of the calyx (and also the external indumentum of the corolla) is in fact quite variable in S. aurifodinae , and even on the type specimen some calyces are sparsely villose on the inside of the lobes.

Conservation status:— IUCN Red List Category: Vulnerable [VU D2]. The extent of occurrence is estimated as 1410.124 km 2 and the area of occupancy as 20 km 2, both within the limit for Endangered under criteria B1 and B2. The species is known from five subpopulations (two of which are in the Moukalaba Doudou National Park) corresponding to four locations (sensu IUCN 2012). The areas where it occurs are sparsely populated, and the species apparently favours secondary habitats such as roadsides, so there is no evidence of an immediate threat. Nevertheless, due to its restricted range and small number of locations, the species qualifies for Vulnerable status under criterion D2.

Additional specimens examined:— GABON. Nyanga: Doudou Mountains, Chantier SNF– Bakker , 29 November 2003, C.C.H. Jongkind 5825 ( BR, WAG) ; Chantier CEB, ca. 65 km SSW of Doussala, 17 May 1985, J.M. Reitsma, B. Reitsma, F.J. Breteler & A.M. Louis 1011 ( MO, WAG) ; Eastern slopes of Doudou-mountains , 20 April 1987, J.M. Reitsma, B. Reitsma & C. Wilks 3366 ( MO, WAG) ; forestry concession of Bakker , 6 km N of Igotchi, 29 October 2003, J.J. Wieringa, J.L.C. H. van Valkenburg & B. Nziengui 5026 ( MO, WAG) .

Figures

FIGURE 8. Distribution of Sabicea arborea, S. aurifodinae and S. becquetii.

FIGURE 9. Sabicea batesii. 1, portion of stem with one leaf and stipules; 2, flowering stem; 3, bract; 4, section of short-styled flower; 5, disk. Sabicea aurifodinae; 6, portion of stem with two unequal leaves and stipules; 7, flowering stem; 8, bract seen from inside; 9, section of short-styled flower; 10, anthers, seen from front (left) and back (right); 11, disk; 12, cross section of ovary. From N. Hallé 2125 (1–5) & N. Hallé 6137 (6–12). Drawing by N. Hallé, reprinted with permission from Hallé (1966: 203).