Xylopia congolensis De Wildeman, Ann. Mus. Congo, Ser . 5, Bot. 1: 41-42. 1903.

Johnson, David M. & Murray, Nancy A., 2018, A revision of Xylopia L. (Annonaceae): the species of Tropical Africa, PhytoKeys 97, pp. 1-252 : 51-54

6. Xylopia congolensis De Wildeman, Ann. Mus. Congo, Ser. 5, Bot. 1: 41-42. 1903. Fig. 14G

Type.

DEMOCRATIC REPUBLIC OF THE CONGO ["Belgian Congo "]. Kongo Central Province, Inkisi-Kisantu [ “Kisantu”], 1900, J. Gillet 812 (lectotype, here designated: BR!; isotypes: BR! [0000008824707, 0000008824714, 0000008824721, 0000008824769, 0000008824776]) .

Description.

Tree up to 20 m tall, d.b.h. up to 50 cm; bark medium brown to red-brown, flaking. Twigs brown to shiny reddish brown or orange-brown, eventually light gray to gray-brown, glabrous, the bark sometimes exfoliating in strips, often marked with sharp ridges decurrent from both sides of petiole base. Leaf with larger blades 6.9-11.5 cm long, 2.6-4.4 cm wide, subcoriaceous to chartaceous, discolorous, oblanceolate to narrowly elliptic, apex acuminate, the acumen 4-11 mm long, base cuneate and decurrent, glabrous on both surfaces; midrib slightly impressed to plane adaxially, raised and sharply keeled abaxially, secondary veins brochidodromous, 9-12 per side, diverging at 45-75° from the midrib, often festooned with extra loops on the outside, secondary and higher-order veins indistinct to slightly raised adaxially, raised abaxially; petiole 3-8 mm long, shallowly canaliculate, glabrous or with a few hairs. Inflorescences axillary or from the axils of fallen leaves, 1-4-flowered, appressed-pubescent to glabrate; pedicels arising from axils independently, rarely from a common peduncle ca. 2 mm long, pedicels 3.4-6.7 mm long, 0.7-1.0 mm thick, often curved; bracts 2-4, caducous, rarely persistent, 0.8-1.5 mm long, semicircular to lunate, apex rounded; buds narrowly oblong, apex obtuse. Sepals slightly spreading at anthesis, free or 1/8-1/6-connate, 1.5-2.5 mm long, 2.0-2.5 mm wide, coriaceous, triangular to triangular-ovate, apex acute to obtuse, appressed-pubescent abaxially. Petals white, pale green, or yellowish white in vivo; outer petals slightly spreading at anthesis, 12.7-22 mm long, 2.1-3.3 mm wide at base, 1.0-2.3 mm wide at midpoint, coriaceous or slightly fleshy, linear-ligulate, apex obtuse, densely puberulent except for small glabrous patch at base adaxially, appressed-pubescent abaxially; inner petals more or less erect at anthesis, 10.3-18.6 mm long, 0.9-1.0 mm wide at base, 0.6-0.9 mm wide at midpoint, coriaceous or slightly fleshy, linear or sometimes slightly spatulate, apex obtuse, base with differentiated fleshy or membranous margins, densely puberulent on both surfaces except in basal concavity and on fleshy margins. Stamens 48-61; fertile stamens 1.5-1.8 mm long, oblong, apex of connective 0.4-0.5 mm long, conical, not overhanging anther thecae, long-papillate, anthers 8-10-locellate, filament 0.3-0.5 mm long; outer staminodes 1.2-1.5 mm long, oblanceolate, apex obtuse; inner staminodes apparently absent; staminal cone absent. Carpels 3-5; ovaries 1.0-1.6 mm long, oblong, densely pubescent, stigmas discrete, not connivent, 0.4-0.7 mm long, narrowly oblong to clavate, glabrous. Torus flat, 1.7-2.1 mm in diameter. Fruit of up to 3 glabrate monocarps borne on a pedicel 12-14.8 mm long, 1.6-2 mm thick, glabrate or with scattered hairs; torus 3-4.7 mm in diameter, 2.5-3 mm high, globose. Monocarps 3.7-4.6 cm long, 0.6-0.9 cm wide, 0.8-1.0 cm thick, linear-oblong, weakly torulose, apex rostrate, the beak ca. 2.5 mm long, base contracted into a more or less distinct stipe ca. 6 mm long, 2.4-2.5 mm thick, longitudinally wrinkled and obliquely striate, faintly verrucose; pericarp ca. 0.5 mm thick. Seeds up to 5 per monocarp, in a single row, lying parallel to long axis, 10.4-11.2 mm long, 6.8-7.0 mm wide, ca. 6.7 mm thick, ellipsoid, elliptic in cross-section, truncate at micropylar end, rounded or obtuse at chalazal end, brown, smooth, dull to shiny, raphe/antiraphe not evident, micropylar scar 2.7-4 mm long, 3-3.7 mm wide, roughly circular; sarcotesta absent; aril color in vivo unknown, straw-colored when dried, fimbriate, extending the length of the seed, membranous, smooth.

Phenology.

Specimens with flowers have been collected in February and once in August, with large buds in January, and with fruits in October.

Distribution

(Fig. 15 ). Gabon and southwestern Democratic Republic of the Congo, occurring in evergreen rainforest at 200-500 m.

Local names.

Lukanga (Hauzer 18), mvouma (Fang, Hladik 1689 part A, part C), ngambo (Bakota, Hladik 1689 part C).

Additional specimens examined.

GABON. Nyanga: Mayombe bayaka, Tchibanga, région du Nyanga, 2 Feb 1915 (fl), Le Testu 2006 (A, BM, MO-2 sheets, P) .- Ogooué-Ivindo: SEGC, 11 Jan 2017 (buds), Abernethy s. n. (OWU); Ipassa, vieille route, Makokou , 500 m, 29 Feb 1972 (fl), Hladik 1689 part A (P); Ipassa, 10 km S of Makokou, 29 Feb 1972 (fl), Hladik 1689 part C ( US) ; Station d’Etudes des Gorilles et Chimpanzés, forêt de l’Aeroport, 2 Feb 1993 (fl), Tutin 80 (MO); Reserve de Lope-Okanda , 0°25'S, 11°30'E, 20 Dec 1990 (tiny buds), White [series 2] 285 (MO), Reserve de Lope-Okanda , 0°25'S, 11°30'E, 10 Feb 1991 (fl), White [series 2] 345 (MO); Lope Reserve , Pothos death site, Aug 1993 (fl), White 960 (MO) . DEMOCRATIC REPUBLIC OF THE CONGO. Kongo Central: Kisafu ( Maduda ), Oct 1951 (fr), Hauzer 18 (BR) .

In the herbarium this species is separable with difficulty from X. quintasii s. s. but is more readily distinguished in the field. The flush of leaves on new growth is white (L. White and K. Abernethy, personal communication), and in central Gabon the flowers appear mostly in February. The most striking quantitative difference is in the size of mature flowers, with the outer petals of X. congolensis sometimes exceeding 20 mm in length. There are, however, small differences that can be discerned in herbarium material. The leaves of X. congolensis tend to be proportionally narrower than those of X. quintasii and are usually glabrous; the decurrent ridges on the twigs are raised and persistent, the pedicels are relatively short, and the bracts are caducous well before anthesis. In the Lopé Reserve field site, both species are present and have maintained discrete phenologies over a period of many years (K. Abernethy and E. Bush, personal communication). Associates of X. congolensis mentioned by collectors are species of Parinari , Treculia , and Pentadesma (Hauzer 18), and understory Marantaceae (White [series 2] 285).

Boutique (1951b) expressed the opinion that Xylopia congolensis was not necessarily conspecific with X. quintasii , calling attention to the smaller seeds and shorter aril of the type specimen. While the fruits and seeds on the type specimen of X. congolensis are immature, thus accounting for these differences, the specimen shows vegetative features that place it with a number of specimens from Gabon.

Figures

Figure 14. Xylopia quintasii, X. congolensis, and X. aurantiiodora. A-F X. quintasii A Seed, lateral view B Outer petal, adaxial view C Monocarp, lateral view D Flower, lateral view E Inner petal, adaxial view F Leaf G X. congolensis, flower, lateral view. H-K X. aurantiiodora H Leaf I Inner petal, adaxial view showing tooth J Flower, lateral view K Monocarp, attached to pedicel L Outer petal, adaxial view. A, C from Reitsma 1423 (WAG) B, D-F from de Wilde et al. 9156 (WAG) G from Tutin 80 (MO) H, K from Harris 752 (MO) I, J, L from Harris & Fay 1846 (MO).

Figure 15. Distributions of Xylopia aurantiiodora, X. congolensis, and X. quintasii. Bolder lines represent country borders, fainter lines lakes and major rivers.