Uvariopsis zenkeri Engl., Notizbl. Koenigl . Bot. Gart. Berlin 2: 298 (1899)

Dagallier, Leo-Paul M. J., Mbago, Frank M., Couderc, Marie, Gaudeul, Myriam, Grall, Aurelie, Loup, Caroline, Wieringa, Jan J., Sonke, Bonaventure & Couvreur, Thomas L. P., 2023, Phylogenomic inference of the African tribe Monodoreae (Annonaceae) and taxonomic revision of Dennettia, Uvariodendron and Uvariopsis, PhytoKeys 233, pp. 1-200 : 1

Uvariopsis zenkeri Engl., Notizbl. Koenigl. Bot. Gart. Berlin 2: 298 (1899)

Figs 85A-F , 86

Type.

Cameroon - South Region • G.A. Zenker 1117 (holotype: B! (B 10 0153124); isotypes: BM! (BM000554075), G! (G00420324), GOET! (GOET005734), HBG! (HBG502515), K! (K000199042), LE! (LE00012462), M! (M0107936), P! (P00362604), S! (S07-11029), WU! (WU0025790)), Bipinde, Urwaldgebiet; 3°05'N, 10°25'E ; 1896.

Description.

Shrub to tree 2-5 m tall, D.B.H 1.5-2 cm; young branches densely pubescent to pubescent, old branches glabrous. Petiole 2-5.5 mm long, 1-1.5 mm wide, pubescent to glabrous. Leaf lamina 110-158 mm long, 36-58 mm wide, length:width ratio 2.1-3.4, elliptic to obovate, papyraceous to coriaceous, base acute to decurrent, apex acuminate, acumen 10-24 mm long, surface above glabrous, surface below puberulent to glabrous when young, glabrous when old; midrib impressed above, raised below, glabrous above, pubescent to glabrous below; secondary veins 6-13 pairs, brochidodromous, impressed above, raised below; tertiary veins reticulate. Flowers unisexual, male and female flowers similar, on same individuals (plant monoecious). Flower buds globose to subovoid. Male and female inflorescences borne on trunk, old branches or old axillary, composed of 1, (sub)sessile flower. Peduncle inconspicuous. Flower pedicel 0-7 mm long, 1-1.5 mm in diameter, pubescent. Bracts 1 to 2 (5 in bud) at base, upper bract 1-4 mm long, 2-5 mm wide, ovate, pubescent outside, glabrous inside. Sepals 2, 3-7 mm long, 4.5-7 mm wide, broadly ovate, basally fused, pubescent outside, glabrous inside, brown. Petals 4, 6-13 mm long, 4-7 mm wide, length:width ratio 1.5-2.2, ovate to triangular, fused at base over ca. 50 % of their length, pubescent outside, glabrous inside, brown outside. Male flowers: stamens 100 to 150, ca. 0.5 mm long, ca. 0.3 mm wide, anthers linear, connective prolongation truncate or absent. Female flowers: carpels 13 to 22, 1.5-3 mm long, 1-1.5 mm wide, velutinous, free; stigma 0.1-0.5 mm long, ca. 1 mm wide, coiled, glabrous. Fruiting pedicel 2-10 mm long, ca. 2.5 mm in diameter, pubescent. Monocarps, 1-3, ca. 37 mm long, ca. 17 mm wide, length:width ratio ca. 2.2, cylindrical, slightly veined and constricted between the seed when dried, tomentose, brown, subsessile; stipe ca. 1 mm long, ca. 2 mm wide, tomentose. Seeds 10-12 per monocarp, biseriate, ca. 13 mm long, ca. 7 mm wide, ellipsoid.

Distribution.

Endemic to Lower Guinean Domain of the Guineo-Congolian Region: Cameroon.

Habitat and ecology.

Lowland mature or secondary rain forests. Soil: rocky, humic, volcanic. Altitude: 0-m asl.

Phenology.

Flowers and fruits collected in April.

Notes.

This species resembles Up. bisexualis , Up. congensis and Up. oligocarpa in having elliptic leaves generally less than 16 cm long with decurrent base. It differs from these species in having densely pubescent to pubescent young branches (vs. pubescent to glabrous). It also differs from Up. bisexualis with its unisexual flowers (vs. bisexual flowers). Up. zenkeri has less carpels (13 to 22 vs. 20 to 40 in Up. congensis ), which results in generally 1 to 3 monocarps reaching maturity on the ripe fruit (vs. up to 15 mature monocarps in Up. congensis ). The monocarps of Up. zenkeri are tomentose (vs. glabrate to glabrous in Up. congensis and pubescent to sparsely pubescent in Up. oligocarpa ), slightly constricted between the seeds (vs. not constricted between the seeds in Up. oligocarpa ) (Table 6 ).

Conservation status.

This species is endemic to Cameroon. It occurs in nine locations, only four of which are situated in protected areas ( Campo-Ma’an National Park, Ebo National Park, Mont Cameroun National Park, Takamanda National Park). It has been previously assessed as Vulnerable VU under criteria B2ab(i,ii,iii,iv,v) ( Texier and Stévart 2021).

Additional specimens examined.

Cameroon - South Region • G.A. Zenker 3045 (B, BM, G, K, L, M, MA, WAG), Bipindi; 3°05'N, 10°25'E; 1904 • G.A. Zenker 3228 (G, L, M), Bipinde, Urwaldgebiet; 3°05'N, 10°25'E; 1904 • G.A. Zenker 515 (B, G, G, M, MA, MO, WAG), Bipindi; 3°05'N, 10°25'E; Mar. 1914 • G.P. Tchouto Mbatchou 2846 (KRIBI, WAG), Efoulan, Ongongo and Nkolomekok hills in Akom II area; 2°44'43'N, 10°31'48'E; alt. 1000 m; 25 Apr. 2000 • G.P. Tchouto Mbatchou 3252 (KRIBI, SCA, WAG), Campo-Ma'an area, Massif des Mamelles, Mamelles highlands; 2°33'57'N, 9°56'58'E; alt. 280 m; 23 Apr. 2001 • T.L.P. Couvreur 707 (MPU, WAG, YA), Campo Ma'an National Park, 11 km on trail from Ebinanemeyong village, on road, 7 km from Nyabessan to Campo town ; 2°28'24.59'N, 10°20'41.79'E; 14 Feb. 2015 - South-West Region • D.W. Thomas 3455 (B, K, LBV, MO, WAG), forested lower slope of Mount Cameroon, above Batoke; 4°05'N, 9°05'E; alt. 300 m; 24 Apr. 1984 • D.W. Thomas 7372 (MO, P, WAG), Takamanda Forest Reserve ; 6°13'N, 9°26'E; alt. 500 m; 30 Apr. 1987 • S.N. Ekema 944 (K, SCA); Ndian, Dikome, Mokoko Forest Reserve ; 4°25'11.64'N, 9°03'29.16'E; alt. 120 m; 05 May. 1994 • T.L.P. Couvreur 1027 (MPU, WAG, YA), on trail leading to top of Mt Etinde, after Ekonjo village ; 4°04'02.29'N, 9°09'11.15'E; alt. 756 m; 01 Apr. 2016 • T.L.P. Couvreur 978 (WAG, YA), on top of hill, near Small Ekombe village, 3 km after Kumba on road to Ekondo Titi town ; 4°37'21.52'N, 9°22'26.62'E; alt. 589 m; 13 Jan. 2016 - Unknown major area • J. Osborne 200 (K, WAG), Littoral Province, Ebo Forest proposed National Park. Ebo Forest Research Station-Bekob drinking stream trail; 4°21'N, 10°25'E; 27 Oct. 2006 .

Figures

Figure 85. Uvariopsis zenkeri Engl A leaf, upper side B male flowers on brnch C male flower, one petal removed D stamen E female flower, one petal removed F carpel, front and side view, detail of ovules. Uvariopsis congensis Robyns & Ghesq. G flowering branch with male flower bud H male flower, one petal removed I stamen J flowering branch with female flower K female flower, one petal removed L carpel, side view and detail of ovules M fruit A-E from Zenker 1117 F from Zenker 63 G-L from Tisserant 1363 M from Letouzey 5494. Drawings by Helene Lamourdedieu, Publications Scientifiques du Museum national d'Histoire naturelle, Paris.

Figure 86. Distribution map of Uvariopsis zenkeri. Shades of grey represent elevation, from white (sea level) to darker grey (higher elevation). The inset shows the extent of the map over Africa.