Xylopia gilbertii Boutique, Bull. Jard. Bot. Etat 21: 110-111. 1951.

Johnson, David M. & Murray, Nancy A., 2018, A revision of Xylopia L. (Annonaceae): the species of Tropical Africa, PhytoKeys 97, pp. 1-252 : 91-93

15. Xylopia gilbertii Boutique, Bull. Jard. Bot. Etat 21: 110-111. 1951. Fig. 23F-J

Xylopia ardua Sillans, Rev. Bot. Appliq. 33: 555-556 + pl. 8. 1953. Type. CENTRAL AFRICAN REPUBLIC [ “Oubangi-Chari”]. Boukoko, Dec 1951, C. Tisserant 2329 (lectotype, here designated: P! [00169140]; isotypes: BM! [000510989], P! [00169141, 00169142, 00169143], US! [2679729]).

Type.

DEMOCRATIC REPUBLIC OF THE CONGO ["Belgian Congo "]. Tshopo Province, Yangambi , plateau de la Luweo, alt. 470 m, Nov 1937, J. Louis 6777 (holotype: BR!; isotypes: B! [100249561], BM! [000510912, 000511052], BR! [8824738], K! [000542217], MO! [1639391], P! [00169152], US! [2091368]).

Description.

Tree up to 40 m tall, d.b.h. up to 40 cm, bole slender, cylindrical, with small buttresses at the base; bark brown or mottled with white, yellow, green, or orange-brown, lightly cracked or longitudinally fissured. Twigs brown, eventually gray and longitudinally wrinkled, persistently erect-pubescent, the hairs orange to rusty and 0.3-0.8 mm long; nodes occasionally with two axillary branches. Leaf with larger blades 4.2-9.7 cm long, 2.0-3.3 cm wide, chartaceous to subcoriaceous, slightly discolorous, elliptic-oblong to lanceolate, occasionally oblong or ovate, apex acute to nearly rounded, base broadly cuneate to rounded, erect-pubescent (densely so on the midrib) to glabrate adaxially, persistently erect-pubescent abaxially; midrib plane adaxially, raised abaxially, secondary veins indistinctly brochidodromous, 7-14 per side, diverging at 45-60° from the midrib, plane to slightly raised adaxially, raised abaxially, higher-order veins indistinct adaxially, slightly raised abaxially; petiole 2.8-4 mm long, semi-terete to shallowly canaliculate, densely pubescent. Inflorescences axillary but often clustered at bases of newly elongating shoots, 1-6-flowered, densely pubescent; peduncle 1 per axil, 1.5-2.5 mm long; pedicels 2-6 per peduncle, 1-2 mm long, 1.3-1.7 mm thick; bracts 2, evenly spaced and somewhat overlapping, caducous or persistent, 2.3-3.5 mm long, ovate to broadly ovate, apex obtuse; buds ovoid, apex obtuse or acuminate to an expanded base. Sepals spreading at anthesis, free or connate just at base, sometimes slightly imbricate at base, 1.6-2.4 mm long, 2.8-4.2 mm wide, coriaceous, reniform to semicircular, apex acute to rounded, densely pubescent abaxially. Petals fawn-olive, brown-violet, or purple in vivo; outer petals slightly spreading at anthesis, 6.6-11 mm long, 2.8-6.4 mm wide at base, 2.4-4.4 mm wide at midpoint, fleshy, lanceolate to ovate, apex obtuse, pubescent on distal half and verrucose on proximal half adaxially, densely appressed-pubescent abaxially; inner petals slightly spreading at anthesis, 5.8-9.3 mm long, 3-4 mm wide, 1.4-3.2 mm wide at midpoint, fleshy, lanceolate, apex obtuse to acuminate, base with margin differentiated into two roughly circular glands 0.6-1.4 mm in diameter, pubescent on distal half and glabrous on concavity/claw adaxially, pubescent abaxially. Stamens 80-130; fertile stamens 1.1-1.3 mm long, oblong-clavate, apex of connective 0.3-0.4 mm long, shieldlike to capitate, overhanging the anther thecae, minutely puberulent to glabrous, anthers 10-13-locellate, filament 0.3-0.4 mm long; outer staminodes 1.1-1.3 mm long, broadly clavate, apex obtuse to obliquely truncate; inner staminodes 0.9-1.0 mm long, narrowly oblong to broadly clavate, apex obtuse to truncate; staminal cone 1.3-1.8 mm in diameter, 0.4-0.6 mm high, concealing only the bases of the ovaries, rim laciniate. Carpels 6-11; ovaries 1-1.5 mm long, oblong, pubescent, stigmas connivent, 1.5-2.2 mm long, linear, sparsely pubescent. Torus flat, 1.6-2.2 mm in diameter. Fruit of up to 10 sparsely pubescent monocarps borne on a pedicel 4.5-10 mm long, 1.5-2.5 mm thick, sparsely pubescent; torus 2.8-3.8 mm in diameter, 2.5-2.6 mm high, discoid. Monocarps reddish or purplish green in vivo, endocarp color unknown, 2.5-3.7 cm long, 1-1.3 cm wide, 0.5-0.8 cm thick, oblong to clavate, sometimes irregularly torulose, apex obtuse to obliquely truncate, sometimes with an offset blunt beak 1-1.5 mm long, base contracted into a stipe 5-13 mm long, 1.2-3.5 mm thick, sometimes with a longitudinal groove abaxially, obliquely wrinkled, sparsely verrucose; pericarp ca. 1 mm thick. Seeds up to 6 per monocarp, in a single row, oblique to long axis, 7.4-10 mm long, 4.2-6.7 mm wide, (3.1-) 3.5-5.4 mm thick, ellipsoid, elliptic in cross-section, truncate at micropylar end, rounded at chalazal end, light brown, smooth, dull or slightly shiny, raphe/antiraphe not evident, micropylar scar 1.3-2.2 mm long, 1.5-2.5 mm wide, elliptic, circular, or transversely elliptic; sarcotesta red in vivo; aril absent.

Phenology.

Specimens with flowers have been collected from October to February, and with fruits from February to April, in June, and from October to December.

Distribution

(Fig. 24 ). Scattered in a narrow band from southern Cameroon and northern Gabon east to the southwestern Central African Republic and the north ern Democratic Republic of the Congo; upland forest; 470-900 m. Associates include Coula edulis Baill. and Millettia duchesnei De Wild. Harris (2002) reports the species from the Dzanga-Sangha region of SW Central African Republic, but we have not seen the vouchers.

Local names.

Bompaie bo fufow (Turumbu, Louis 6777), molo-mosoma (Lissongo, Tisserant 625, 2329).

Additional specimens examined.

CAMEROON. A 9 km à l’ouest de Yenga Port Gentil, village situé à 35 km au NNE de Moloundou, 21 Apr 1971 (fr), Letouzey 10707 (P); près Akonetche, PK 95 sur route Minton I (70 km E de Djoum)- Mbalam (140 km ESE de Djoum), 22 Jan 1973 (fl), Letouzey 11876 (BR, K) . CENTRAL AFRICAN REPUBLIC. Boukoko , 17 Jan 1948 (fl), Tisserant 625 (BM, P) . GABON. Ogooué-Ivindo: Bélinga, Mines de Fer, 700-900 m, 4 Jun 1966 (fr), Hallé 3735 (P).- Woleu-Ntem: ca. 9 km ESE Medouneu, Elot, bas inselberg Simanguen , 0°58.62'N, 10°54.01'E, 661 m, 21 Dec 2002 (fr), Ngok Banak et al. 1057 (MO); Inselberg, ca. 28 km ESE of Medouneu, 0°55'N, 11°01'E, 500 m, 3 Feb 1986 (fl, fr), Reitsma et al. 1821 (MO, NY, WAG) . DEMOCRATIC REPUBLIC OF THE CONGO. Tshopo: Territ. Tsangi, Yangambi , 12 Feb 1952 (fl), Donis 3634 (K); Yangambi , 1938 (st), Gilbert 1099 (K, US); Yangambi , 1938 (buds) Gilbert 1423 (K, MO, US); Yangambi , 29 Nov 1935 (fl), Louis 733 (NY, RSA); Yangambi , 470 m, 17 Oct 1936 (yg fr), Louis 2741 (K); Yangambi, réserve-flore Isalowe, 7 Oct 1937 (st), Louis 6324 (FI-T, MO, P); Prov. Orientale, Territ. Tsangi, Yangambi, plateau de l’Isalowe, 12 Mar 1951 (fr), Toussaint 886 (K); Prov. Orientale, Tsangi Territory, Yangambi, environs de la Réserve floristique, Nov 1960 (fr), Yafunga 7 (WAG) .

Xylopia gilbertii is either an uncommon or infrequently collected species. It can be recognized by a combination of the sparse but persistent erect pubescence of the twigs, leaves, and monocarps, the relatively broad but small flowers on short pedicels, and the rounded marginal glands on the inner petals. Xylopia gilbertii shares inner petal glands with X. flamignii and X. toussaintii , but the former has strongly reticulate leaves and more numerous, up to 22, glabrate monocarps, while the latter has proportionately narrower inner petals and less persistent indument of the twigs, leaves, and monocarps. An odd feature of X. gilbertii , not observed in the other two species or in fact in any African Xylopia , is the tendency for inflorescences to be produced at the bases of expanding shoots, such that it is difficult to determine the inflorescence position. Xylopia staudtii has occasionally been confused with X. gilbertii , but lacks the hairy twigs and leaves and the inner petal glands, and has larger and distinctly arillate seeds.

Descriptions of flower color for Xylopia gilbertii are inconsistent. Boutique (1951a), in the protologue for the species, described " Flores lutei," but on the label of the holotype specimen, the flowers are described as “olive-fauve,” i.e. fawn-olive. Other collectors give flower colors such as brown-violet and purple, suggesting a darker color for the flowers. The lighter colors likely represent immature flowers. Endocarp color is unknown, but Gautier-Hion et al. (1985) reported that the seeds are dispersed by birds, monkeys, and small rodents, noting that the small rodents can also be predators on the seeds.

Sillans (1953), while mentioning X. gilbertii in the protologue for Xylopia ardua , did not explain how the two species were to be distinguished. The type specimen of X. ardua , while showing shorter and broader leaves than those of the type of X. gilbertii , overlaps widely with other specimens in both qualitative and quantitative characters, and we have thus placed it in synonomy. Two specimens from northern Gabon, Reitsma et al. 1821 and Ngok Banak et al. 1057, also with broader leaves, both differ somewhat from specimens elsewhere in having subcoriaceous leaves and longer stipes on the monocarps, but otherwise conform to this species .

We calculated an EOO of 249,251 km 2 and an AOO of 52 km 2 for Xylopia gilberti . It was given a conservation assessment of Vulnerable (D2) by Onana and Cheek (2011).

Figures

Figure 23. Xylopia flamignii and X. gilbertii. A-E X. flamignii A Flower, side view B Close-up of adaxial leaf surface, showing raised venation C Leaves D Inner petal, adaxial view E Outer petal, adaxial view F-J X. gilbertii F Flower, side view G Inner petal, adaxial view H Outer petal, adaxial view I, J Leaves. A-E from Bradley 1136 (OWU) F-I from Louis 6777 (MO) J from Letouzey 10707 (P).

Figure 24. Distributions of Xylopia gilbertii, X. toussaintii, and X. flamignii. Bolder lines represent country borders, fainter lines lakes and major rivers.