Xylopia unguiculata 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 : 174

44. Xylopia unguiculata D. M. Johnson & N. A. Murray sp. nov. Fig. 33A-D, L-O

Diagnosis.

Species resembling X. acutiflora in the tree habit, mixture of long and short erect hairs on the twigs, short pedicels 2.8-4.8 mm long, and outer petals up to 2.5 mm wide at midpoint, but differing in the cuneate to broadly cuneate leaf base and the strongly torulose monocarps with seeds in a single row and a prominent beak at the apex.

Type.

GABON. Nyanga Province, ca. 50 km SW of Forestry Camp Doussala , 2°36'S, 10°35'E, 20 Feb 1986, J. M. Reitsma & B. Reitsma 1923 (holotype: WAG! [0050003]; isotypes: MO! [3879083], NY! RSA!).

Description.

Tree up to 17 m tall, rarely a shrub, d.b.h. up to 16 cm; bark smooth. Twigs brown, pilose-pubescent, with a mixture of dense hairs 0.1-0.2 mm long and sparser longer hairs 0.7-1.3 mm long, at length gray-brown to dark brown, glabrate, with the bark somewhat exfoliating; nodes rarely with two axillary branches. Leaf with larger blades 8.9-12 cm long, 3.0-4.5 cm wide, chartaceous, slightly discolorous, elliptic to somewhat oblanceolate, obovate, or oblong, apex acuminate, the acumen 4-13 mm long, base cuneate to broadly cuneate, glabrous except for the pubescent midrib adaxially, sparsely appressed-pubescent to glabrate abaxially; midrib slightly impressed adaxially, raised abaxially, secondary veins indistinctly brochidodromous, 8-14 per side, diverging at 45-75° from the midrib, these and higher-order veins plane to slightly raised adaxially, raised abaxially; petiole 2.5-6 mm long, canaliculate, sparsely pubescent. Inflorescences axillary or from the axils of fallen leaves, 1-flowered, densely pubescent; pedicels not pedunculate, 2.8-4.8 mm long, 1.4-1.5 mm thick; bracts 3-4, imbricate, persistent, 2.3-3.8 mm long, orbicular, apex rounded to emarginate; buds linear, apex obtuse. Sepals slightly spreading at anthesis, 1/4-1/3-connate, 2.8-3.9 mm long, 3.4-3.6 mm wide, coriaceous, broadly ovate, apex acute to obtuse, densely brown-tomentose abaxially. Petals white to pale yellow with a patch of purple on the adaxial base in vivo; outer petals slightly spreading at anthesis, 22-30 (-46) mm long, 3.4-4.5 mm wide at base, (1.4-) 2.2-2.5 mm wide at midpoint, coriaceous, linear, apex acute to obtuse, glabrous and somewhat verrucose on lower half but otherwise puberulent adaxially, sericeous abaxially; inner petals appearing bent outward at the base at anthesis, 15.5-25 (-29) mm long, 3.0-3.6 mm wide at base, 1.2-1.6 mm wide at midpoint, coriaceous, linear, apex acute, glabrous on proximal 1/3-1/2 but otherwise puberulent adaxially, puberulent except for the glabrous base abaxially. Stamens 90-160; fertile stamens 1.2-1.9 mm long, clavate to narrowly oblong, apex of connective purple in vivo, 0.2-0.4 mm long, dome-shaped to shieldlike, overhanging the anther thecae, minutely papillate, anthers 9-13-locellate, filament 0.2-0.7 mm long; outer staminodes 1.2-1.9 mm long, clavate or oblong, apex obtuse to truncate; inner staminodes 0.8-0.9 mm long, clavate, apex truncate; staminal cone 1.9-2.1 diameter, 0.6-1.1 mm high, concealing the lower half of the ovaries, rim laciniate. Carpels 10-15; ovaries ca. 1 mm long, oblong, densely pubescent, stigmas connivent except for the free apices, ca. 3 mm long, linear, glabrous except for tuft of hairs at apex. Torus flat, 1.8-2.5 mm in diameter. Fruit of up to 20 sparsely pubescent to glabrate monocarps borne on a pedicel 6.7-9 mm long, 3.3-6.5 mm thick, with sepals and bracts persistent, glabrate; torus of fruit ca. 8 mm in diameter, 5 mm high, depressed-globose. Monocarps with green exterior and red endocarp in vivo, 4.9-8.5 cm long, 0.8-0.9 cm wide, 0.7-0.8 cm thick, narrowly oblong, strongly torulose, almost moniliform, apex rostrate, the beak 2.5-6 mm long, strongly curved, base contracted into a flattened and grooved stipe 8-18 mm long, 1.9-2.1 mm thick, slightly wrinkled and verrucose; pericarp 0.1-0.3 mm thick. Seeds up to 8 per monocarp, in a single row, parallel or oblique to long axis, 11.9-12.4 mm long, 6.6-7.5 mm wide, 6.0-7.0 mm thick, oblong, more or less circular in cross-section, truncate at micropylar end, rounded at chalazal end, smooth or slightly bumpy, dull, raphe/antiraphe not evident, micropylar scar 3.3-4.6 mm long, 2.9-4.5 mm wide, broadly elliptic or roughly circular; sarcotesta unknown in vivo, sometimes forming a white crust on dried seeds; aril absent.

Phenology.

Specimens with flowers have been collected in February, March, May, July, and December, and with fruits from October to December.

Distribution

(Fig. 34 ). Gabon, with one collection from the northern part of the country near the border with Cameroon and the remainder from southern Gabon, in primary rainforest or exploited high forest, at elevations of 250-650 m.

Additional specimens examined.

GABON. Nyanga: Tchibanga , 5 Oct 1907 (fr), Le Testu 1179 (BM, P); forêts du Mayombe, Tchibanga, Dabilila, 15 Nov 1908 (fr), Le Testu 1446 (BM, P); Mayombe bayaka, Dabilila, 11 Dec 1908 (fl), Le Testu 1514 (BM-2 sheets, MO, P); région Nyanga, Tchibanga, 8 Dec 1914 (fr), Le Testu 1903 (BM, P); chantier CEB, ca. 50 km SW of Doussala, 2°36'S, 10°35'E, 26 Aug 1985 (buds), Reitsma & Reitsma 1401 (MO, NY, RSA) ; about 30 km NW of Doussala, in the direction of Bongo, 400 m, 16 Mar 1988 (fl), de Wilde & Jongkind 9393 (MO, WAG).- Ogooue-Maritime: 32 road-km N of Igotchi-Mouenda, Bakker timber concession, 250 m, 02°41'S, 10°30'E, 13 May 1977 (fl), McPherson 16960 (MO), McPherson 16960A (MO).-Woleu-Ntem: région entre Ogooué et Cameroun, Mbabou, 31 Jul 1933 (fl), Le Testu 9208 (BM, K, P) .

Xylopia unguiculata bears monocarps with distinctive claw-like apices; the specific epithet alludes to this apex shape. The illustration of the fruit identified as X. acutiflora in Le Thomas (1969) shows the appearance of the apex well. The new species shares with X. acutiflora from West Africa a tree habit and a short pedicel covered by imbricate bracts. Xylopia unguiculata differs, however, in its cuneate to broadly cuneate, rather than broadly cuneate to rounded leaf base, broader outer petals, and a larger number of falciform, strongly torulose monocarps with the prominent claw-like beak and seeds in a single row. [Note: The illustrations in Le Thomas (1969) provided for Xylopia acutiflora show a mixture of two species, the flowers and floral parts being based on Bates 1852, identified here as X. thomsonii , and the fruits on Le Testu 1179, identified as X. unguiculata .]

Xylopia unguiculata may prove to be more widely distributed, but as known at present it is endemic to the Congo Subregion within the Congolian Biogeographic Region of Linder et al. (2012). It is of potential conservation concern, with an EOO of 15,417 km 2 and AOO of 20 km 2.

Figures

Figure 33. Xylopia unguiculata, X. acutiflora, and X. piratae. A-D, L-O X. unguiculata A Monocarp, lateral view B Seed C Leaves D Flower, lateral view L, M Staminodes, abaxial view N Stamen, abaxial view O Carpel, lateral view with ovary wall cut away to show arrangement of ovules E-G X. acutiflora E Monocarp, lateral view, attached to pedicel F Leaves G Flower, lateral view H-K X. piratae H Flower bud, lateral view I Leaves J Flower, lateral view K Fruit. A-B from Le Testu 1179 (BM) C-D from Reitsma & Reitsma 1923 (NY) E-G from Beentje 879 (WAG) H-J from de Koning 4999 (WAG) K from de Wilde 356 (P) L-O from McPherson 16960 A (MO).

Figure 34. Distributions of Xylopia acutiflora, X. dinklagei, X. monticola, X. piratae, X. thomsonii, and X. unguiculata. Bolder lines represent country borders, fainter lines lakes and major rivers.