Xylopia aurantiiodora De Wildeman & T. Durand, Ann. Mus. Congo, Ser . 2, Bot. 1(1): 4. 1899.

Johnson, David M. & Murray, Nancy A., 2018, A revision of Xylopia L. (Annonaceae): the species of Tropical Africa, PhytoKeys 97, pp. 1-252 : 49-51

5. Xylopia aurantiiodora De Wildeman & T. Durand, Ann. Mus. Congo, Ser. 2, Bot. 1(1): 4. 1899. Fig. 14H-K

Artabotrys aurantiiodorus [ “aurantiodorus”] (De Wildeman & T. Durand) Engler, Monogr. afrik. Pflanzen-Fam. 6: 76. 1901. Type. DEMOCRATIC REPUBLIC OF THE CONGO ["Belgian Congo"]. Équateur Province [ “Région III"], Mbandaka [ “Coquilhatville”], 24 Jan 1896, A. Dewèvre 660 (holotype: BR!; isotypes: BR! [8824271, 8824677, 8824684, 8824691]).

Xylopia bequaertii [ “bequaerti”] De Wildeman, Pl. bequaert. 1: 469-470. 1922. Type. DEMOCRATIC REPUBLIC OF THE CONGO ["Belgian Congo"]. Tshopo Province, Kisangani [ “Stanleyville”], bords boisés de la Tshopo, 27 Feb 1915, J. C. C. Bequaert 6994 (holotype: BR!).

Description.

Tree or shrub 2-10 m tall, d.b.h. up to 30 cm; bark light colored. Twigs brown to gray, glabrous or with sparse hairs 0.2-0.3 mm long, usually marked by two ridges decurrent from each petiole base, epidermis eventually exfoliating. Leaf with larger blades 6.3-11.1 cm long, 2.5-4.7 cm wide, chartaceous to subcoriaceous, discolorous, the lower surface tan-colored, elliptic to oblong-elliptic, occasionally oblanceolate or obovate, apex rounded, obtuse, or acute, occasionally emarginate, base cuneate and decurrent, glabrous adaxially, glabrous or with a few scattered hairs abaxially; midrib plane to slightly raised adaxially, raised and somewhat keeled abaxially, secondary veins brochidodromous, 10-14 per side, diverging at 60-70° from the midrib, these and higher-order veins forming a raised reticulum on both surfaces; petiole 2.5-7 mm long, shallowly canaliculate, glabrate or sparsely pubescent. Inflorescences axillary, 1-5-flowered, occasionally with two pedicels borne on a common peduncle, glabrous to sparsely pubescent; peduncle 1.5-2.0 mm long; pedicels 3.5-7.1 mm long, 0.5-1.0 mm thick; bracts 2-3, the uppermost often just beneath the sepals, caducous, 1.1-1.5 mm long, semicircular, apex rounded; buds panduriform, apex obtuse. Sepals free and somewhat imbricate at the base, 1.5-2.1 mm long, 1.9-2.4 mm wide, coriaceous, semicircular to triangular, apex apiculate, pubescent abaxially with hairs extending beyond margins to form cilia. Petals white or pale yellow to greenish yellow in vivo; outer petals erect with the apices slightly spreading at anthesis, 8.9-12 mm long, 2.4-3.5 mm wide, 1.8 mm wide at midpoint, fleshy, ligulate-lanceolate, apex obtuse, pubescent except for glabrous center of basal concavity adaxially, buff-brown pubescent abaxially; inner petals with apices divergent, 9.3-11.2 mm long, 1.2-2.3 mm wide at base, ca. 0.8 mm wide at midpoint, narrowly oblong, apex obtuse, base with differentiated margin, with a truncate tooth 0.8-1.1 mm long overhanging basal concavity, densely puberulent on both surfaces except for the glabrous differentiated margins and basal concavity. Stamens 40-60; fertile stamens ca. 1.8 mm long, oblong, apex of connective 0.2-0.3 mm long, globose, not overhanging the anther thecae, papillate, anthers 6-8-locellate, filament ca. 0.5 mm long; outer staminodes ca. 1 mm long, broadly clavate, apex rounded, emarginate, or bilobed; inner staminodes absent; staminal cone absent. Carpels 3-5; ovaries 0.7-1 mm long, globose, pubescent; stigmas discrete, not connivent, 0.6-0.8 mm long, narrowly oblong, glabrous except for fine setae at the apex. Torus flat, 1.5-1.8 mm in diameter. Fruit of up to 3 glabrate monocarps borne on a pedicel 6.5-10 mm long, 1.2-1.8 mm thick, slightly curved, sparsely pubescent to glabrate; torus 2.8-4 mm in diameter, 2-2.5 mm high, depressed-globose. Monocarps green in vivo, 3.3-6.5 cm long, 0.7-0.9 cm wide, 0.7-0.8 cm thick, finger-shaped to narrowly oblong, strongly torulose, apex acute to rostrate, beak up to 5 mm long, base abruptly contracted into a stipe 5.5-9.5 mm long, 2-3 mm thick, wrinkled and somewhat flattened, striate and somewhat shining; pericarp 0.1-0.4 mm thick. Seeds 1-4 per monocarp, in a single row, parallel or slightly oblique to long axis, 13.3-21 mm long, 5.5-8.3 mm wide, 5.5-7.5 mm thick, narrowly ovoid to oblong, circular to elliptic in cross-section, obliquely truncate at micropylar end, distinctly pointed at the chalazal end, light reddish brown, smooth, raphe/antiraphe not evident, micropylar scar 2.7-4.5 mm long, 2-2.5 mm wide, elliptic; sarcotesta absent; aril red in vivo, orange-brown when dried, fimbriate, extending the length of the seed, membranous, smooth.

Phenology.

Specimens with flowers have been collected from January to March and from May to November; fruits have been collected in May, June, August, and September.

Distribution

(Fig. 15 ). Xylopia aurantiiodora is found in the Congo River basin in the Democratic Republic of the Congo, the southern Central African Republic, and eastern Cameroon, with disjunct occurrences in the Cabinda Province of Angola and near Lolodorf in southern Cameroon. It grows in riparian forest, on riverbanks, and in inundated forest, from near sea level up to 470 m.

Local name.

Gongo-sange (Bangala, Robyns 465).

Additional specimens examined.

CAMEROON. Eastern Province, west bank of the Sangha River, 02°23'N, 16°10'S, 22 May 1988 (fr), Harris & Fay 752 (K, OWU); Est, west bank of Sangha River opposite Ndakan camp and 2 km S, 02°21'N, 16°08'E, 12 Feb 1989 (fl), Harris & Fay 1846 (GH, MO); Mbekou près Moloundou, 17 Oct 1949 (fl), Letouzey SRFK 1374 (P); env. de Lolodorf, 1919 (fl), Rouyer s. n. (L). CENTRAL AFRICAN REPUBLIC. Sangha-Mbaere, west bank of Sangha River, opposite Bayanga, ca. 200 m upstream, 02°55'N, 16°21'E, 20 Feb 1991 (fl), Harris 2750 (OWU); bord. Riv. Ouaka [ “Waka”] 30 km N Bambari, 29 Jan 1923 (fl), Tisserant 936 (BM, P, US). DEMOCRATIC REPUBLIC OF THE CONGO. Bas-Uele: Terr. Bambesa, bord de l’Uéle, 20 Feb 1956 (st), Gerard 2162 (WAG).- Équateur: Eala, 7 Jul 1933 (fl), Corbisier-Baland 1687 (BM, K, MO, P, US); Scierie de Loukoléla, 26 Aug 1912 (st), Chevalier 28289 (P); Eala, Couteaux 425 (K, P); Botsima, parc au layon central, 1°09'S, 21°57'E, 28 Mar 1991 (fl), Dhetchuvi 1067 (BR); District de la Tshuapa [Basankusu, fide Boutique 1951b], Jul 1934 (fl), Dubois 485 (K, MO, P); district de la Tshuapa, Aug 1938 (fr), Dubois 972 (K); Popolo, forêt inondée de la Mongala, 10 Aug 1955 (fr), Evrard 1594 (BR); Popolo, forêt marécageuse de la Mongala, Evrard 1658 (P); Territ. Bolomba, R. Busisa or Busira, en amont de Isalo, Oubangui, 2 Mar 1958 (bud), Evrard 3601 (K); Territ. Monkoto, river Yenge, 25 km from mouth, 2 Aug 1958 (bud), Evrard 4431 (K); Territ. Bokota, Watsi Kengo, inundated forest of the Salonga (hautes eaux), 14 Nov 1957 (fl), Evrard 2964 (K); Wangata, Aug 1930 (fl), Lebrun 922 (A, K, MO, P, PR); entre Eala et Boyeka, rive droite de la Ruki, 8 Sep 1925 (fl, fr), Robyns 465 (B, BR-2 sheets, K); environs de Mbandaka [ “Coquilhatville”], 15 Sep 1925 (fr), Robyns 580 (A, B, K-2 sheets, P).- Maniema: Secteur Bangengele, Parc National Proposé de la Lomami, ca. 3.9 km au NNO de Katopa (en ligne directe) en descendant la rivière Lomami, 02°43'00"S, 025°05'03"E, 430 m, 3 May 2015 (fl), Gereau et al. 7632 (MO).-Mongala: Monza (village) along the Loika (Itimberi), 02.0491°N, 022.743°E, 335 m, 30 Jun 2009 (fr), Stoffelen 453 (MO).-Nord-Ubangi: entre Banzyville et Yakoma (Ubangi), Feb 1931 (fl), Lebrun 2167 (K, MO, P).-Tshopo: Terr. Isangi, Yangambi, île Tutuku, Jul 1963 (fl) Bolema 1192 (K, P, WAG-2 sheets); 0°26'S, 25°28'E, Ubundu, rives du fleuve Zaire et îles en amont d’Ubundu, 12 Mar 1978 (fl), Lejoly 2915 (BR); près d’Ubundu, bord d’une île sur le Zaire, 11 Mar 1978 (fl), Lisowski 47959 (K); env. de Yangambi, bord du Zaire au pied de la Falaise, 28 Apr 1979 (bud), Lisowski 52352 (K); Yangambi, 17 Aug 1937 (fl), Louis 5804 (B, BM, F-2 sheets, K, MO, NY, P, US); Yangambi, 9 Feb 1938 (fl), Louis 7839 (B, K, MO, P, US), Yangambi, 21 Mar 1938 (fl), Louis 8542 (MO); Yangambi, 28 Jul 1938 (fl), Louis 10543 (BM, EA, FI-T, K, P), Yangambi, 3 Aug 1938 (fr), Louis 10671 (BM, EA, FI-T, K, P); Yangambi, 13 Aug 1938 (fr), Louis 10790 (BM, EA, FI-T, K, P), Yangambi, 29 Jan 1939 (fl), Louis 13464 (BM, K); Yangambi, île Tutuku, 31 Jul 1939 (fl), Louis 15674 (K, MO, P, US). ANGOLA. Maiombe, banks of river Luali, Gossweiler 7168 (BM, COI-00067909); banks of the river Luali at Sera, Maiombe, 7 May 1917 (fl), Gossweiler 7169 (BM, COI-0067910); Maiombe Portuguesa, Sera, proximum flumen Luali-Chiloango, Jun 1924 (fl, fr), Gossweiler 9006 (B, BM, K).

Xylopia aurantiiodora differs from X. congolensis and X. quintasii in having a prominent tooth on the inner surface of the inner petals (Fig. 14I ), strongly striate monocarps that are acute at the apex, and larger pointed seeds. The tooth of the inner petal is especially useful for identification, because it appears early in petal development and is visible even in young buds. The connivance of the bases of the inner petals is more pronounced in this species than in other species of the genus and is reminiscent of Artabotrys ; presumably on this basis, X. aurantiiodora was moved to Artabotrys by Engler and Diels (1901), who erected a special section for it. Xylopia aurantiiodora also differs from X. congolensis and X. quintasii in both habit and habitat, being a riverine tree reaching only 10 m in height, while the other two species are trees of upland forest commonly reaching a height of 20 m or more. Associated species of X. aurantiiodora mentioned on herbarium labels include Irvingia smithii , Trichilia retusa , and Uapaca heudelotii . The species epithet marks the field observation of Dewèvre that the flowers had the scent of citrus flowers.

We treat Xylopia bequaertii as a taxonomic synonym of X. aurantiiodora , as previous authors have (e.g. Boutique 1951b), observing only that, in his original description of X. bequaertii , De Wildeman (1922) made no mention of X. aurantiiodora but instead contrasted X. bequaertii with X. striata Engler, drawing attention to floral differences between the two species as well as the larger number of secondary veins in the leaves of X. bequaertii .

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.