Uvariodendron citriodorum (Le Thomas) 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 citriodorum (Le Thomas) Dagallier & Couvreur, comb. et stat. nov.

Figs 13 , 14

≡ Uvariodendron molundense var. citrata Le Thomas, Fl. Gabon No. 16, 283 (1969). Type. Gabon - Ogooué-Ivindo • N. Hallé 525 (holotype: P! (P00363400), sheet here designated, isotypes: K! (K000198798, K000198799), MO! (MO216993, MO216994), P! (P00363398), WAG! (WAG0065739)), Bélinga, mines de fer, sommet de Belvédère; 1°08'N, 13°12'E; alt. 800 m; 15 Aug. 1966.

Description.

Tree to shrub 4-5 m tall, D.B.H. unknown; young branches glabrous, old branches glabrous. Leaves with strong lemon smell when crushed. Petiole 6-10 mm long, 1.5-3.5 mm wide, sparsely pubescent to glabrous. Leaf lamina (183) 250-337 mm long, 72-97 mm wide, length:width ratio 2.3-4.2, elliptic to oblong, coriaceous, base acute to rounded (sometimes minutely decurrent at the very base, and decurrent on young leaves), apex attenuate, surface above glabrous, surface below glabrous; midrib impressed above, raised below, glabrous above, sparsely pubescent to glabrous below; secondary veins 12-18 pairs, weakly brochidodromous, impressed above, raised below; tertiary veins reticulate. Inflorescences borne on branches or axillary, composed of 1 sessile flower. Flowers bisexual, buds globose, sessile, 5-6 mm high, 5-7 mm in diameter, velutinous. Mature flower unknown, measures taken from flower buds or fruits. Bracts 1 to 4, upper bract ca. 5 mm long, ca. 7 mm wide, broadly ovate, semi clasping the pedicel, velutinous outside, glabrous inside. Sepals 3, ca. 7 mm long, ca. 6 mm wide (measures taken from bud), imbricate, velutinous outside, glabrous inside, color unknown. Outer petals 3, length, shape, indumentum and color unknown. Inner petals 3, length, shape, indumentum and color unknown. Stamens number unknown, ca. 1 mm long, ca. 0.2 mm wide, anthers linear, connective prolongation truncate. Carpels 10 to 20, ca. 2 mm long, ca. 0.4 mm wide, sparsely pubescent, free; stigma 0.5 mm long, 0.5 mm wide, pubescent. Fruiting pedicel 10-12 mm long, 2-5 mm in diameter, pubescent to glabrous. Monocarps 5 to 20, 25-40 mm long, 9-20 mm wide, length:width ratio 1.9-2.9, cylindrical, oblong, straight, truncate or rounded at apex, pubescent to glabrate, pale greyish green to red; sessile to shortly stipitate, stipe 0-5 mm long, 3-5 mm wide, pubescent to glabrous. Seeds 9-14 per monocarp, biseriate, 13 to 15 mm long, ca. 11 mm wide, semicircular.

Distribution.

Endemic to Lower Guinean Domain of the Guineo-Congolian Region. Known from one area in Gabon: Bélinga, mines de fer, and one locality in Republic of the Congo: Les Saras.

Habitat and ecology.

Mature rain forests on rocky soils. Altitude: 800-950 m a.s.l.

Phenology.

Fruits collected in July and November.

Vernacular names.

Gabon: ‘Bombamba’ in Bakota ( Hallé 2896).

Etymology.

The specific epithet refers to the strong lemon smell of the plant. The epithet ' Uvariopsis citrata ' would prevail as it is the one given by Le Thomas for the variety. However, this specific epithet is already taken by Uvariopsis citrata Couvreur & Niangadouma, from the genus Uvariopsis , which is closely related to Uvariodendron . Following the recommendation 23.A.3.h from Turland et al. (2018) ("Avoid [the specific epithets] that have been used before in any closely allied genus"), we choose the specific epithet ' Uvariodendron citriodorum '.

Notes.

This species differs from the other species, and particularly from Ud. molundense , in having leaves emitting a strong lemon scent when fresh material is crushed. Apart from this character, this species is morphologically very similar to Ud. molundense . However, as Ud. citriodorum and Ud. molundense are not monophyletic (Fig. 1 , Suppl. materials 1, 2), they can’t be considered the same species following the phylogenetic species concept.

Preliminary conservation status.

This species is only known from one locality in Gabon and one locality in the Republic of the Congo. The EOO of the species is estimated at 2,256 km2 and its AOO at 20 km2. The unique occurrence in the Republic of the Congo dates back more than 30 years and the occurrences in Gabon are situated in Bélinga. Although the project of exploitation of the Bélinga iron ore deposits has been canceled, this locality is still threatened by a possible future exploitation of the ore. Following IUCN criterion B, it is thus assigned a preliminary conservation status of Endangered EN B1a(i,ii,iii,iv)+2a(i,ii,iii,iv).

Additional specimens examined.

Gabon - Ogooué-Ivindo • M.S.M. Sosef 2219 (BR, K, LBV, MO, WAG), Bélinga, Mines de Fer , 4 km on the road to Mvadi; 1°05'N, 13°12'E; alt. 900 m; 05 Nov. 2005 • N. Hallé 2896 (P), Bélinga; 1°05'N, 13°08'E; alt. 900 m; 29 Oct. 1964 • N. Hallé 3082 (P), Bélinga; 1°05'N, 13°08'E; alt. 950 m; 07 Nov. 1964 • N. Hallé 13 (P), Bélinga, mines de fer, route du Belvédère; 1°05'N, 13°12'E; alt. 950 m; 08 Jul. 1966 • N. Hallé (P), Bélinga, mines de fer, route du pt. B3; 1°06'N, 13°12'E; 25 Jul. 1966 • N. Hallé (K, MO, P), Bélinga, mines de fer; 1°08'N, 13°12'E; alt. 950 m; 16 Jul. 1966. Republic of the Congo - Kouilou • H. de Foresta 1759 (P), Les Saras, piste Cofibois, environs de la plantation Coobama de 1987; 4°22'S, 12°22'E; 25 Nov. 1988 .

Figures

Figure 1. Phylogenetic trees of the Monodoreae inferred with ASTRAL, based on 334 nuclear genes trees. The branch support is given as local posterior probability (LPP) in three shades of greys. For the details on the specimens see Suppl. material 3. Insets: flowers of A Ophrypetalum odoratum (Couvreur 82) B Sanrafaelia ruffonammari (Dagallier 31) C Asteranthe asterias (Dagallier 10) D Hexalobus crispiflorus (no specimen associated) E Uvariastrum zenkeri (no specimen associated) F Isolona hexaloba (no specimen associated) G I. cauliflora (Dagallier 44) H Monodora grandidieri (Dagallier 26) I M. myristica (living specimen at NY conservatory) J M. tenuifolia (Couvreur 1019) K Mischogyne elliotana (no specimen associated) L Uvariodendron gorgonis (Dagallier 38) M Ud. molundense (Bidault 2222) N Ud. connivens (Couvreur 1016) O Ud. var. fuscum (Couvreur 990) P Uvariopsis congensis (Lachenaud 1384) Q Up. lovettiana (Couvreur 97 b) R Up. bakeriana (Couvreur 1000) S Up. submontana (Couvreur 627) T Up. pedunculosa (Couvreur 878). Photos CC BY-NC 4.0 A, D-F, J, N, O, Q-T Thomas Couvreur B, C, G-I, L Leo-Paul Dagallier K Carel Jongkind M Ehoarn Bidault P Olivier Lachenaud.

Figure 13. Uvariodendron citriodorum (Le Thomas) Dagallier & Couvreur A entire specimen sheet with branch, leaves and flower buds B flower bud showing bracts, semi-side view C fruit with monocarps, some monocarps transversally cut, top view D fruit with monocarps, some monocarps transversally cut, side view. A, B Halle 525 (type) C, D Sosef 2219. Photos Leo-Paul Dagallier.

Figure 14. Distribution map of Uvariodendron citriodorum. Shades of grey represent elevation, from white (sea level) to darker grey (higher elevation). The inset shows the extent of the map over Africa.