Sabicea sanguinosa subsp. viridis O. Lachenaud, Zemagho & Sonké, 2020

Lachenaud, Olivier, Zemagho, Lise & Sonké, Bonaventure, 2020, A synopsis of the Sabicea floribunda group (Rubiaceae) from Central Africa, including three new species, Candollea 75 (1), pp. 115-143 : 140

7b. Sabicea sanguinosa subsp. viridis O. Lachenaud, Zemagho & Sonké , subsp. nov.

( Fig. 12F , 13A–B ).

Holotypus: GABON. Ogooué-Maritime: région du Lac Alombié, ± 7 km au N de Mpaga, 0°50'20"S, 9°27'14"E, 14.X.2014, fl. & fr., Lachenaud, Ikabanga & Lafferty 1918 ( BRLU!; isotype: BR!, G!, LBV!, MO!, P!, WAG!) .

A typo differt calycis bracteisque pallide viridibus, nec atrorubris.

Distribution, ecology and phenology. – This subspecies is endemic to the lower Ogooué delta in Gabon, between the coast and Lake Alombié ( Fig. 10 ); it has thus a more southern range than subsp. sanguinosa . It occurs in the same habitat as the latter, and is locally very abundant.

Flowers recorded in October-November, fruits in October (probably in other months as well).

Conservation status. – The extent of occurrence (EOO) of S. sanguinosa subsp. viridis is estimated to be 483 km ², and its area of occupancy (AOO) to be 16 km ², both values being within the limit for “Endangered” status under subcriteria B1 and B2. The taxon is endemic to the Ogooué delta in Gabon, and is known from five specimens, representing four subpopulations. It is not known from any protected area, but probably occurs in the Wonga-Wongué Presidential Reserve since it has been collected very close to its limits. In spite of its restricted range, it occurs in a sparsely populated area, and is a locally abundant plant of forest edge habitats, which benefits from small-scale forest clearing (e.g. that induced by selective logging). As a result, there is no evidence of a particular threat, and the taxon is assessed as “Least Concern” [LC] using the IUCN Red List Categories and Criteria ( IUCN, 2012).

Paratypi. – GABON. Ogooué-Maritime : Préfecture de M’paga , à env. 7 km au N du lac Alombié, au S de la réserve de Wonga Wongué , 11.X.2014, fl. & fr., Bidault et al. 1691 ( BR, BRLU, MO, P); delta de l’Ogooué en face de Port-Gentil , au S de la Pointe Fétiche , 22.XI.2016, fl., Lachenaud et al. 2270 ( BR, BRLU, G, K, LBV, MO, P, WAG); env. 5 km au SE de Mbilapé, 24.XI.2016, fl., Lachenaud et al. 2314 ( BR, BRLU, G, LBV, MO, P, WAG); riv. de Kendié en aval de Mbilapé , rive E , 25.XI.2016, fl., Lachenaud et al. 2335 ( BR, BRLU, LBV, MO, WAG).

Figures

Fig. 12. – Sabicea rubiginosa O. Lachenaud, Zemagho & Sonké: A. Plant with flowers and fruits; B. Lower side of leaf; C. Inflorescence; D. Infructescence with mature (white) and immature fruits (green). Sabicea sanguinosa subsp. sanguinosa: E. Apex of flowering stem. Sabicea sanguinosa subsp. viridis O. Lachenaud, Zemagho & Sonké: F. Stem with flowers and fruits, note bullate leaves. [A: Sonké & Ikabanga 6155; B, D: Lachenaud et al. 2105; C: Bidault et al. 1329; F: Bidault et al. 1691] [Photos: A: B. Sonké; B, D: O. Lachenaud; C, F: E. Bidault; E: J.-P. Vande weghe]

Fig. 13. – Sabicea sanguinosa subsp. viridis O. Lachenaud, Zemagho & Sonké: A. Inflorescence (short-styled flowers); B. Mature infructescence. Sabicea segregata Hiern: C. Flowering stem; D. Detail of inflorescence with short-styled flowers; E. Stem with immature fruits; F. Mature infructescence. [A–B: Lachenaud et al. 1918; C: Dessein et al. 2148; D: Bidault et al. 1316; E: Dessein et al. 1862; F: Sonké & Ikabanga 6139] [Photos: A: O. Lachenaud; B: D.I. Lafferty; C, E: S. Dessein; D: E. Bidault; F: B. Sonké]

Fig. 10. – Distribution map of Sabicea proselyta (N. Hallé) Razafim. et al. (circles), S. rubiginosa O. Lachenaud, Zemagho & Sonké (stars) and S. sanguinosa (N. Hallé) Razafim. et al. (triangles: subsp. sanguinosa; squares: subsp. viridis O. Lachenaud, Zemagho & Sonké).