Sabicea sciaphilantha subsp. hirsuta Zemagho, O. Lachenaud & Sonké, 2017

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

13a. Sabicea sciaphilantha subsp. hirsuta Zemagho, O. Lachenaud & Sonké , subsp. nov. ( Fig. 28 L )

Type :— GABON. Makandé, 0°41’S 11°54’E, 22 November 1993, M.M. Dhetchuvi 1401 (holo-, BRLU!) .

Sabicea sciaphilantha subsp. hirsuta differs from the typical subspecies in the the stems with long patent hairs (vs. with hairs appressed or absent) and in the densely villose outside of corolla (vs. glabrous or sparsely villose on the lobes and upper half of the tube).

Stems and petioles villose, with patent, stiff hairs 3–4 mm long, intermingled with sparse to dense appressed, woolly hairs. Hypanthium glabrous to villose. Calyx tube glabrous or densely villose outside. Corolla densely villose outside except the base of the tube.

Etymology:— The subspecific epithet refers to the long-pubescent stems.

Distribution: —Lower Guinea Domain. This taxon occurs sparsely in Equatorial Guinea, central Gabon, and southwest Republic of Congo ( Fig. 29 ).

Habitat and ecology: —Primary and secondary forest, often along tracks; up to 900 m in altitude.

Phenology: —Flowering in October–November; immature fruits in January.

Discussion: —The sole collection from Equatorial Guinea (Nguema et al. 277), one from the Republic of Congo (F. Hallé 1626) and two from Gabon (Breteler et al 14850, N. Hallé & Cours 5945) are sterile specimens. They are referred to this taxon on account of the typical stem indumentum. The latter collection was initially referred with doubt to S. batesii by Hallé (1966: 204) and later thought to belong to Pseudosabicea aurifodinae var. crystallina by Hallé (1971: 317); although it differs from both S. batesii and S. crystallina in being much more pubescent. This specimen shows peculiar pubescent galls on the stems, which at first sight could be taken for inflorescences.

Conservation status:— IUCN Red List Category: Vulnerable [VU D2]. The extent of occurrence is estimated as 27,448.469 km 2 and the area of occupancy as 36 km 2; the latter value falls within the threshold for Endangered under criterion B2. The taxon is known from six subpopulations from five locations (sensu IUCN 2012); three of them are within protected areas, Lopé National Park in Gabon, Altos de Nsork National Park in Equatorial Guinea, and the Dimonika Biosphere Reserve in Congo. The areas where it occurs are sparsely populated and the taxon seems relatively adaptable to secondary habitats, so there is no evidence of an immediate threat. However, due to the small number of known locations, the taxon qualifies for Vulnerable status under criterion D2.

Additional specimens examined (Paratypes):— EQUATORIAL GUINEA. Parc national de Nsork, Obamicu, 7 August 1998, N. Nguema, P. Esono & J. Lejoly 277 ( BRLU) . GABON. Makande surroundings, about 65 km SSW of Booué, 30 January 1999, F.J. Breteler, G. Caballé, Y. Issembe, J.M. Moussavou & O. Pascal 14850 ( WAG) ; Makandé , 30 November 1993, M.M. Dhetchuvi 1532 ( BRLU) ; Région de la «Forêt des Abeilles», campement rivière Makandé (2 km en amont de son embouchure dans l’Offoué), 14 January 1999, F. Hallé 4537 ( WAG) ; Ovala , env. d’Etéké, carrière micaschiste des recherches filoniennes, ca. 900 m, 16 May 1963, N.Hallé & G. Cours 5945 (P); Réserve de Lopé-Okanda, 26 October 1990, L.J.T. White [series 2] 170 ( MO) . REPUBLIC OF CONGO. 30 km on Dolisie-Mvouti road, just behind the telephone antenna, 21 September 2015, T.L.P. Couvreur, J.-M. Moutsamboté & C. Mampouya 799 ( IEC, WAG) . Dimonika , chemin de la “tour des physiciens”, 1986, H. de Foresta 813 (P); Col des Bambas, 13 April 1969, F. Hallé 1626 (P) .

Figures

FIGURE 28. Sabicea sciaphilantha subsp. sciaphilantha (A–K) & subsp. hirsuta (L). A, flowering stem; B, node with stipules, reduced leaf and base of normal leaf; C, detail of inflorescence with one short-styled flower; D, detail of a hair from the corolla mouth; E, flower bud; F, section of short-styled flower; G, flower bud; H, long-styled flower; I, section of long-styled flower; J, section of calyx and ovary; K, fruit; L, node with stipules, reduced leaf and base of normal leaf. From Sonké & Ikabanga 5957 (A), Lachenaud et al. 1375 (B), Lachenaud et al. 1272 (C–F), Bidault et al. 1303 (G–I), Lachenaud et al. 1289 (J–K), Breteler et al. 14850 (L). Drawing by Hans De Vries.

FIGURE 29. Distribution of Sabicea sciaphilantha subsp. sciaphilantha and S. sciaphilantha subsp. hirsuta.