Xylopia globosa D. M. Johnson & N. A. Murray, 2018

Johnson, David M. & Murray, Nancy A., 2018, A revision of Xylopia L. (Annonaceae): the species of Tropical Africa, PhytoKeys 97, pp. 1-252 : 37-39

2. Xylopia globosa D. M. Johnson & N. A. Murray sp. nov. Figs 3A , 9A, G-I

Diagnosis.

Species resembling Xylopia africana in its short broad flowers with outer petals thicker and broader than the inner petals, but differing in the glabrous twigs and leaves, the leaf blades consistently larger (15.7-23.5 cm long, 8.3-11.7 cm wide), the smaller and wider sepals, the more rounded apices of the outer petals, and the conspicuously keeled inner petals.

Type: GABON. Ogooué-Lolo, Chantier Bambidie (CEB), ca. 70 km E of Lastoursville, 57 km on CEB road to Okondja, 0°46.6'S, 13°23.6'E, 325 m, 1 Nov 2005, M. S. M. Sosef et al. 2180 (holotype: WAG! [1540447]; isotypes: OWU-2 sheets! WAG! [1540446, 1540448, 1540449]).

Description.

Small tree or shrub up to 8 m tall, d.b.h. up to 25 cm, bole cylindrical, knee roots [ex Sosef et al. 2180] on lower 0.5 m of trunk; bark light gray, smooth. Twigs light brown to gray-brown, eventually reddish brown, glabrous or with a few weak hairs ca. 0.4 mm long and then soon glabrate; nodes with axillary branches not seen. Leaf with larger blades 15.7-23.5 cm long, 8.3-11.7 cm wide, subcoriaceous, paler or discolorous abaxially, oblong to oblong-elliptic or oblong-oblanceolate, apex cuspidate, the cusp 3.5-9 mm long, or rarely emarginate, base rounded to broadly cuneate and decurrent on petiole, glabrous on both surfaces; midrib slightly impressed adaxially, raised abaxially, secondary veins weakly brochidodromous, 10-14 per side, diverging at 65-75° from the midrib, slightly raised on both surfaces, higher-order veins indistinct or slightly raised adaxially, plane to slightly raised abaxially, usually forming a conspicuous reticulum on both surfaces; petiole 9-26 mm long, canaliculate adaxially, glabrous. Inflorescences axillary, 1-2-flowered, finely appressed-pubescent; peduncle 1 per axil, 3.5-5.2 mm long; pedicels 1-2 per peduncle, 6.7-10.5 mm long, 2.6-2.9 mm thick; bracts 3, evenly spaced on pedicel, persistent, 2.4-4 mm long, broadly ovate to semicircular, apex rounded; buds depressed-globose, apex rounded. Sepals spreading at anthesis, 1/3-1/2-connate, 4.8-6 mm long, 7-10 mm wide, coriaceous, crescent-shaped to nearly semicircular, apex rounded or obtuse, sparsely pubescent to glabrate abaxially. Petals yellow in vivo; outer petals slightly spreading at anthesis, 9-13.4 mm long, 10-10.5 mm wide at base, 8.7-9.3 mm wide at midpoint, fleshy, broadly ovate, apex obtuse to rounded, finely pubescent on both surfaces except for the glabrous adaxial concavity; inner petals slightly spreading at anthesis, 7.8-9.3 mm long, 1.5-1.6 mm wide at base, 3.5-4.7 mm wide at midpoint, chartaceous to coriaceous, narrowly rhombic, deeply concave, strongly keeled abaxially, apex acuminate, base with undifferentiated margin, pubescent at apex on both surfaces but otherwise glabrous and somewhat verrucose. Stamens ca. 100; fertile stamens 1.7-2.3 mm long, narrowly oblong, apex of connective 0.5-0.8 mm long, shieldlike, overhanging anther thecae, puberulent to glabrate, anthers 8-11-locellate, filament 0.3-0.4 mm long; outer staminodes 1.6-1.8 mm long, wedge-shaped to quadrate, apex truncate; inner staminodes 1.7-2.6 mm long, clavate or narrowly oblong, apex rounded; staminal cone 6-7 mm in diameter, 1.3-1.9 mm high, concealing only the bases of the ovaries, rim laciniate. Carpels ca. 15; ovaries 1.8-2.5 mm long, narrowly oblong, densely pubescent, stigmas loosely connivent, 5-5.7 mm long, linear, studded on sides with round tubercles. Torus flat, 6-7.5 mm in diameter. Fruit and seeds unknown.

Phenology.

Specimens with flowers were gathered in September and November.

Distribution

(Fig. 10 ). Known from four scattered localities in Gabon and from one locality in the southern Republic of the Congo; secondary forest and forest edge; 80-325 m.

Local name.

Ntsua (Normand s. n.).

Additional specimens examined.

GABON. Estuaire: Cristal Mountains , 9 km S of Kinguélé, ca. 0°24'N, 10°15'E, 80 m, 21 Sep 1994 (st), Breteler et al. 12978 (WAG); Estuaire du Gabon, sud de Chinchoua [0.0149°N, 9.8094°E], 16 Sep 1959 (fl), Normand s. n. (P).- Moyen-Ogooué: about 10 km NNW of Ndjolé, 0°04'S, 10°47'E, 150 m, 25 Sep 1994 (st), Breteler et al. 13000 (MO, WAG) . REPUBLIC OF THE CONGO. Environs de Dimonika, forêt vieille secondaire entre tour meteo et piste Kuilila-Makaba , 14 Dec 1982 (st), Cusset 1200 (P-01963323) .

The flowers of Xylopia globosa are large, fleshy, and spherical, and scarcely resemble those of a Xylopia . In addition, the leaves of this new species are the largest of any African Xylopia , oblong to elliptic in shape, and usually sharply cuspidate at the apex, and allow confident identification of sterile specimens. The species is most similar to X. africana from which it differs in several additional floral features: the sepals are wider than long and crescent-shaped to semicircular, the outer petals are rounded at the apex, and the inner petals have a crestlike keel on the abaxial surface.

Fruits and seeds of Xylopia globosa are not yet known. A specimen from Equatorial Guinea (Litoral: Monte Alen National Park, Monte Mitra , 01°21'46"N, 9°57'40"E, 1000 m, 30 Sep 2005 (fr), Leal et al. 817 (MO)) is possibly a collection of this species with fruits. This specimen was taken from a tree 10 m tall, the fruit described as having black seeds with red arils. The plant was growing on a swampy mountain summit at 1000 m in elevation. The specimen was initially identified as X. staudtii , but its leaf blades are thinner, larger, and more rounded at the bases than is typical for that species, with a sharply short-acuminate to cuspidate apex. Xylopia staudtii typically has yellow to orange arils, and fruits on a tree 10 m in height would also be unusual. The leaves of this specimen are more similar in shape to those of X. globosa than to those of X. staudtii , but are smaller (largest 12.4 cm long, 5.8 mm wide, with a petiole 5 mm long and acumen 9 mm long) and chartaceous. There are no seeds present on the specimen, only two detached and dehisced monocarps .

Figures

Figure 3. Flowers of representative Xylopia species. A Flower from type collection of Xylopia globosa from Gabon B Xylopia tenuipetala from Mozambique C Xylopia quintasii from Gabon D Xylopia aethiopica from Gabon E Xylopia longipetala from Mali, representing a record for the country not otherwise documented F Xylopia piratae from Ivory Coast G Xylopia odoratissima from Zambia H Xylopia arenaria from Tanzania I Xylopia collina from Tanzania. A, D by Thomas L. P. Couvreur B by Frances Chase C by Ehoarn Bidault E by Philip Birnbaum F by Celine Pirat G by Warren McClelland H and I by D. M. Johnson.

Figure 9. Xylopia globosa and X. africana. A, G-I X. globosa A Leaf G Inner petal, abaxial view, showing keel H Inflorescence, showing four buds and one flower with petals fallen I Outer petal, adaxial view B-F, J, K X. africana B Seed, lateral view with most of aril appendages fallen C Four inflorescences D Seed, micropylar end view E Inner petal, abaxial view F Outer petal, adaxial view J Leaf K Fruit. A, G-I from Normand s. n. (P), B, D, E, F, J, K from Letouzey 14551 (WAG) C from Thomas 4554 (MO).

Figure 10. Distributions of Xylopia africana, X. globosa, and X. staudtii. Bolder lines represent country borders, fainter lines lakes and major rivers.