Uvariodendron fuscum var. magnificum (Verdc.) Dagallier & Couvreur, comb. et, 2023

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

Uvariodendron fuscum var. magnificum (Verdc.) Dagallier & Couvreur, comb. et stat. nov.

Figs 22 , 23

≡ Uvariodendron magnificum Verdc. syn. nov., Kew Bull. 23(3): 515 (1969). Type. Uganda - Western Province • Okodi in Hamilton 696 (holotype: K! (K000198899, K000198900, K000198896, K000198897, K000198898); isotypes: ENT, MHU! (MHU000022, MHU000023, MHU000024)); Ankole District, Kashoya • Kitomi CFR; 0°13'N, 30°15'E; alt. 1050 m; 15 Jun. 1968.

Description.

Young branches with long soft hairs producing a whitish appearance quickly falling off. Petiole 6-20 mm long, ca. 5 mm wide. Leaf lamina 210-750 mm long, 57-215 (250) mm wide, length:width ratio 3-4, base acute to cuneate, apex rounded to acuminate, surface below pilose to glabrous when young, glabrous when old; midrib pilose to glabrous below; secondary veins 23-30 pairs. Flower pedicel 10-15 mm long. Flower not seen, description from Verdcourt (1969). Bracts 5 to 6, upper bract 8-35 mm long, 10-40 mm wide. Sepals 30-55 mm long, 30-43 mm wide. Outer petals 60-70 mm long, 43-47 mm wide. Inner petals 50-53 mm long, 36-38 mm wide, length:width ratio ca. 1.4, elliptic, imbricate at apex. Carpels 150 to 160. Fruiting pedicel 13-18 mm long. Monocarps 10 to 80, 28-60 mm long, 13-32 mm wide, length:width ratio 1.9-2.5, cylindrical, curved, acuminate, pubescent, brownish, fruits not seen, data from Verdcourt (1969). Seeds 1-16 per monocarp, 18 to 23 mm long, 10-11 mm wide.

Distribution.

Endemic to Zambezian Region. Known from only one locality in the Western Province in Uganda.

Habitat and ecology.

Montane forest. Altitude: around 1050 m a.s.l.

Notes.

Ud. fuscum var. magnificum differs from the type variety in having young branches and petioles covered with long soft white hairs producing a whitish appearance quickly falling off (vs. young branches and petiole sparsely pubescent to glabrous). Compared to the type variety, it has larger leaves (21.-75 cm long and 5.7-21.5 (25) cm wide, vs. 16-45 cm long and 4.3-11.8 cm wide), with more secondary veins (23 to 30 vs. 15 to 24). It differs from the type variety and from the var. Uvariodendron fuscum giganteum by its flowers having longer pedicels 10-15 mm long (vs. 0-7.5 mm long), larger sepals (30-55 mm long and 30-43 mm wide, vs. 11-30 mm long and 13-26 mm wide), larger petals (50-70 mm long and 36-47 mm wide, vs. 20-40 mm long and 15-30 mm wide) and more carpels (150 to 160 vs. 20 to 100) (Fig. 4 , Table 4 ). This variety is known from two specimens collected more than 50 years ago in the Kasyoha-Kitomi Forest Reserve. Uganda’s forests have been reported to be degraded ( Obua et al. 2010) so this variety might be threatened.

Additional specimens examined.

Uganda - Western Province • T. Synnott 197 (MHU); Ankole District, North border of Kitomi Forest; 0°07'29.07'N, 30°18'07.11'E; alt. 1070 m; 22 Oct. 1968 .

Figures

Figure 4. Morphological continuum in Uvariodendron fuscum: traits comparison for var. Uvariodendron fuscum fuscum (fusc.), var. Uvariodendron fuscum giganteum (gig.) and var. Uvariodendron fuscum magnificum (mag.). Each point represents a measurement. Vertical bars span the minimum and maximum values of the focal traits. Photos, left: leaf of Couvreur 1046; top right: flower, below view, of Couvreur 1046; below right: flower, top view, of Couvreur 990 (CC BY-NC 4.0 Thomas Couvreur).

Figure 22. Uvariodendron fuscum var. magnificum (Verdc.) Dagallier & Couvreur A young branch with leaves and apical bud B leaf, upper side C longitudinal section of flower bud D flower, semi-side view E carpel with carpel wall partially removed to show arrangement of ovules, side view F young fruit, side view G monocarp, side view H seed, side view. A-H from Okodi in Hamilton 696 (as Ud. magnificum). Drawings by Mary Griesrson, modified from Verdcourt (1969; fig. 2, p. 517), Kew Bulletin 1969 Royal Botanic Gardens, Kew.

Figure 23. Distribution map of Uvariodendron fuscum. Shades of grey represent elevation, from white (sea level) to darker grey (higher elevation). The inset shows the extent of the map over Africa.