Sabicea mildbraedii var. letestui (N. Hallé) 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

10b. Sabicea mildbraedii var. letestui (N. Hallé) Zemagho, O.Lachenaud & Sonké , comb. nov. ( Fig. 22 ) Pseudosabicea mildbraedii ( Wernham 1914: 53) N. Hallé var. letestui N. Hallé, Flore du Gabon 12: 206 (1966). Type:— GABON. Tchibanga , galerie près de la Nyanga, 20 Decembre 1914, G. Le Testu 1933 (holotype P [P00077591]!;

isotypes BR [ BR0000008852014 ]!, P [P00077592] !).

Stems sparsely villose, with long patent hairs ca. 2 mm long, intermingled with a dense caducous felt of appressed woolly hairs in the young stage. Leaves sparsely villose above, with appressed stiff hairs 1–1.5 mm long, and sometimes sparse woolly hairs also present in the very young stage; densely white-felted and sparsely villose with long stiff hairs below. Stipules villose outside at least on the margins, sometimes with sparse woolly hairs present as well. Hypanthium densely villose at least in the upper half. Calyx initially +/- erect, becoming patent and cupshaped after anthesis, and +/- erect again on the fruit; tube densely white-felted outside; lobes broadly ovate to elliptic, 1.3–2 x 1.2–1.5 mm, rounded and often slightly hooded at apex, densely white-felted outside, often willose on the margin, glabrous inside. Corolla lobes densely white-felted outside and sometimes with sparse long stiff hairs near the apex. Fruits densely villose at least in the upper half, with stiff hairs ca. 1.5 mm long, initially directed upwards and later patent.

Distribution: —Lower Guinea Domain. This variety is apparently endemic to southwest Gabon, where it is locally abundant ( Fig. 21 ); it might also occur in adjacent Republic of Congo. Its range closely approaches that of var. glabrescens in the Lambaréné region, although the two varieties have never been found together.

Habitat and ecology: —Forest edges in half-shade, frequently along roads or on the borders with savanna; at 100–250 m altitude.

Conservation status:— IUCN Red List Category: Least Concern [LC]. The extent of occurrence is estimated as 9,420.131 km 2 and the area of occupancy as 48 km 2, respectively within the threshold for Vulnerable and Endangered under criteria B1 and B2. The taxon is known from 12 subpopulations representing 9 locations (sensu IUCN 2012), including one protected area (Moukalaba Doudou National Park) and thus would qualify for Vulnerable status under subcriterion B1a. However, being a common species of secondary habitats in its range, it is not threatened at present.

Phenology: —Flowers in February, April–May and October–December; immature fruits in February and September–October.

46 • Phytotaxa 293 (1) © 2017 Magnolia Press

ZEMAGHO ET AL. TAXONOMIC REVISION OF SABICEA SUBGENUS ANISOPHYLLAE

Phytotaxa 293 (1) © 2017 Magnolia Press • 47

Additional specimens examined:— GABON. Eastern foothills of the Doudou mountain , 8 December 1984, J.C. Arends., J.J.F.E. de Wilde, & A.M.Louis 693 ( BR, MO, WAG) ; Mabounié , 45 km SE of Lambaréné, 13 November 2013, E. Bidault, E. Akouangou & J.-Y. Serein 1267 ( BRLU) ; Nyanga: Doussala , 26 September 2000, H.P. Bourobou, T. Nzabi, B. Nziengui & J.F. Mayombo-Nzengue 279 ( BR, MO, P, WAG) ; Doudou Mountains National Park , c. 8 km S of Peny, 16 February 2008, S. Dessein, O. Lachenaud, S. Janssens, Y. Issembe & T. Nzabi 1909 ( BR, WAG) ; Mabounié , 12 November 2013, O. Lachenaud, T. Stévart, D. Ikabanga, Y. Issembé, A. Boupoya & J.-D. Kaparidi 1329 ( BRLU, LBV, MO) ; chantier CEB, Doussala , ca. 25 km SSW of Doussala, 16 May 1985, J.M. Reitsma, B. Reitsma, F.J. Breteler & A.M. Louis 957 ( BR, MO, WAG) ; Mabounié , 12 October 2012, B. Sonké & D. Ikabanga 5992 ( BR, BRLU) ; Mabounié , 45 km SE of Lambaréné, 5 February 2013, B. Sonké, E. Bidault, E. Akouangou, D. Ikabanga & J.-N. Boussiengui 6191 ( BR, BRLU, MO) ; Monts Doudou, au Sud-Ouest du village Moukoualou , qui se trouve à 6 km Sud de Mourindi ( Brigade de Faune de Moukalaba ), 21 March 2000, M.S.M. Sosef, Y. Isembe, H. P. Bouroubou & J.-M. Moussavou 910 ( MO, P, WAG) ; forestry concession of Bakker , 6 km N of Igotchi, 29 October 2003, J.J. Wieringa, J.L.C. H. van Valkenburg & B. Nziengui 5032 ( BR, MO, WAG) ; old logging road leading southwards of CBG chantier Peni , 18 April 2005, J.L. C. H. van Valkenburg, J. Degreef, Y. Azizet Issembé & J.-N. Boussiengui 3108 ( BR) .

Figures

FIGURE 21. Distribution of Sabicea mildbraedii var. glabrescens and S. mildbraedii var. letestui.

FIGURE 22. Sabicea mildbraedii var. letestui. A, flowering stem; B, detail of node with inflorescence, stipules and reduced leaf; C, ovary and calyx, lateral view; D, calyx, viewed from above; E, short-styled flower (calyx and ovary removed); F section of shortstyled flower, with style; G, section of calyx and ovary; H, long-styled flower (calyx and ovary removed); I, section of long-styled flower (calyx and ovary removed); J, fruit. From Wieringa et al. 3032 (A, E–F), Reitsma et al. 957 (B), Arends et al. 693 (C–D), Lachenaud et al. 1329 (G–I), Sonké & Ikabanga 6191 (J). Drawing by Antonio Fernandez.