Xylopia thomsonii Oliver, Fl. trop. Afr. 1: 31. 1868.

Johnson, David M. & Murray, Nancy A., 2018, A revision of Xylopia L. (Annonaceae): the species of Tropical Africa, PhytoKeys 97, pp. 1-252 : 168-173

43. Xylopia thomsonii Oliver, Fl. trop. Afr. 1: 31. 1868. Fig. 39A-C

Xylopicrum thomsonii (Oliver) Kuntze, Revis. gen. pl. 1: 8. 1891. Type. NIGERIA ["Upper Guinea"]. Rivers State, Old Calabar, s. d., W. C. Thomson 63 (holotype: K! [000199064]).

Xylopia pyrifolia Engler, Pflanzenw. Ost-Afrikas C, 179. 1895. Type. DEMOCRATIC REPUBLIC OF THE CONGO. Ituri Province, Bataibo am Duki, 850 m, 7 Nov [1891], F. L. Stuhlmann 2781 (holotype: B! [100153155]).

Xylopia tenuifolia Engler & Diels, Notizbl. Königl. Bot. Gart. Berlin 2: 298. 1899.

Xylopicrum tenuifolium (Engler & Diels) Kuntze, Deutsch. Bot. Monatsschr. 21: 173-174. 1903. Type. CAMEROON. Southwest Region, Urwald zwischen Mowange und Isongo [? = Port Isongo, 4°04'N, 9°01'E], Mar 1897, P. R. Preuss s. n. (type B, apparently destroyed).

Xylopia seretii [" sereti "] De Wildeman, Ann. Mus. Congo, Sér. 5, Bot. 3: 79-80. 1909. Type. DEMOCRATIC REPUBLIC OF THE CONGO ["Belgian Congo"]. Haut-Uele Province, bords d’une riviere sur la route de Faradje à Vankerkhovenville, 12 Apr 1906, F. Seret 555 (holotype: BR!; isotype: BR! [0000008824370]).

Description.

Shrub or small tree up to 10 m tall, often with lianescent branches that may extend up to 10 m, d.b.h. up to 17.3 cm. Twigs light to dark brown, erect-pubescent, the hairs 0.1-1.3 mm long, but often with a mix of denser short (0.1-0.5 mm) hairs and sparser long (0.8-1.3 mm) hairs, eventually brownish gray, glabrate, with the bark exfoliating; nodes rarely (seen in one specimen) with two axillary branches. Leaf with larger blades 8.4-13.7 cm long, 2.5-4.7 cm wide, chartaceous, concolorous or more often discolorous, lanceolate, elliptic to oblong, or oblong-oblanceolate, apex acuminate, the acumen 3-16 mm long, base cuneate to rounded, rarely almost truncate, glabrous except for the pubescent midrib adaxially, sparsely appressed-pubescent to glabrate abaxially; midrib slightly impressed to plane adaxially, raised abaxially, secondary veins irregularly brochidodromous, 11-17 per side, diverging at 45-90° from the midrib, these and higher-order veins slightly raised but indistinct adaxially, raised abaxially; petiole 1.5-5.5 mm long, shallowly canaliculate, sparsely pubescent. Inflorescences axillary or from axils of fallen leaves, 1(-2)-flowered, rusty-sericeous; pedicels not pedunculate, 2.5-7.9 mm long, 0.8-1.3 mm thick; bracts 3-6, usually closer together and more overlapping toward pedicel base, persistent, 1.6-3.5 mm long, semicircular, elliptic, or ovate, apex obtuse, acute, slightly acuminate, or sometimes bilobed; buds linear, apex acute, sometimes slightly falciform. Sepals erect or slightly spreading at anthesis, 1/6-2/5-connate, 1.8-3.8 mm long, 2.6-3.0 mm wide, chartaceous to coriaceous, ovate, elliptic, or triangular, apex acute, acuminate, or sometimes obtuse, rusty-sericeous abaxially. Petals white, cream, or pale mauve in vivo; outer petals somewhat spreading at anthesis, (14.6-) 22-49 mm long, 2.4-3.8 mm wide at base, 1.0-2.0 mm wide at midpoint, linear, apex acute to obtuse, puberulent, becoming glabrous toward the base adaxially, rusty-sericeous, becoming glabrous at the base abaxially; inner petals curved outward to weakly geniculate but curved inward toward the apices at anthesis, 16-33 mm long, 2.1-3.2 mm wide at base, 0.6-1.2 mm wide at midpoint, coriaceous, linear, apex acute, base with undifferentiated margin, transversely thickened at the widest point, longitudinally ridged on both surfaces, puberulent on both surfaces but becoming glabrous toward the base. Stamens ca. 200; fertile stamens 1.2-1.8 mm long, narrowly oblong; apex of con nective 0.2-0.4 mm long, dome-shaped, minutely papillate, anthers 9-13-locellate, filament 0.3-0.5 mm long; outer staminodes 1.3-1.8 mm long, clavate to oblong, apex obtuse to obliquely truncate; inner staminodes 0.7-1.2 mm long, clavate to oblong, apex rounded to truncate; staminal cone 1.3-2.0 mm in diameter, 0.5-1.1 mm high, concealing the lower portion of the ovaries, rim laciniate. Carpels 7-13; ovaries 0.9-1.3 mm long, oblong, densely pubescent, stigmas connivent, 1.8-3.4 mm long, linear-falcate, apices pubescent. Torus 1.7-2.6 mm in diameter. Fruit of up to 12 glabrate monocarps borne on a pedicel 5-12 mm long, 2.2-7.5 mm thick, basal bract or sepals sometimes persistent, sparsely appressed-pubescent; torus of fruit 2-9 mm in diameter, 3.5-5 mm high, globose. Monocarps with a green exterior and red to red-purple endocarp in vivo, 2.1-6.5 cm long, 0.6-1.2 cm wide, 0.5-0.6 cm thick, narrowly oblong and often somewhat falciform, weakly torulose, apex obtuse or occasionally with a broad beak 1-4 mm long, base contracted into a stipe 3-11 mm long, 1.7-2.7 mm thick, smooth to longitudinally or obliquely wrinkled, verrucose; pericarp 0.2-0.3 mm thick. Seeds up to 9, commonly 4-8 per monocarp, in a single row, lying oblique or occasionally nearly perpendicular to long axis, 9.2-12.3 mm long, 5.5-6.7 mm wide, 4.8-6.3 mm thick, ellipsoid to oblong, elliptic to nearly circular in cross section, truncate at micropylar end, rounded at chalazal end, brown, smooth or with shallow pits or wrinkles, dull to slightly shiny, raphe/antiraphe sometimes visible but flush with seed surface, micropylar scar 2.5-4.5 long, 1.5-3 mm wide, broadly elliptic to nearly circular; sarcotesta thin, waxy, green in vivo, sometimes visible as a white crust on dried seeds; aril absent.

Phenology.

Specimens with flowers have been collected in all months of the year except August, most frequently from November to May. Specimens with fruits have been collected in all months except March and August.

Distribution

(Fig. 34 ). Occurs from southeastern Nigeria east to South Sudan and south to northern Angola and south-central Democratic Republic of the Congo, in understory of mature forest or gallery forest, occasionally in marshy forest or forest edges near water, at elevations from sea level to ca. 1000 m.

Local names.

Akwi (Ewondo, Breteler 931), anzungunzungu (Zande, Gerard 1611), apanjinji (Kibila, Hart 284), azungu-zungu (de Graer 241), likungu (Turumbu, Louis 1842), sange (Hart 68), sangi tingoo (Central African Republic, Harris & Fay 607).

Representative specimens.

NIGERIA. Loe, Ibadan District, Ainslie 169 (PR); Calabar Province, Agoi Forest Reserve, 26 Jan 1962 (fr), Binuyo FHI 45456 (K-2 sheets); Lagos, (fl), Dalziel 1144 (M); without definite locality [probably Sapoba], Kennedy 169 (A); "Southern Nigeria" [probably Sapoba], Kennedy 2270 (A-2 sheets, BM, F, MO, US); Oban, 1912 (fl), Talbot 1353 (BM); Oban, 1912 (fl), Talbot 1486 (BM); Eket District, 1912-13 (fl), Talbot & Talbot 3267 (BM); Iba, Jan 1933 (fl bud), Thomewill 200 (K). CAMEROON. Bitya, near the River Dja [ “Ja”], s. d. (fl), Bates 1852 (K); S bank of Lobé R. SE of Gr. Batanga ferry, 2°52'N, 9°54'E, 11 Oct 1969 (fl), Bos 5475 (B, K, MO, P, WAG-3 sheets); forest along river Sanaga near Goyoum 20 km W of Deng Deng, ca. 635 m, 27 Jan 1961 (fl, fr), Breteler 931 [Letouzey 3261] (BR, K, P, WAG-2 sheets); Bétaré Oya, 5 km along road to Bert oua, ca. 900 m, 17 Feb 1961 (fl), Breteler 1063 (A, FI-T, K, M, P, WAG-2 sheets); Bétaré Oya, 5 km along road to Bertoua, ca. 900 m, 26 Feb 1961 (fr), Breteler 1137 (WAG-2 sheets); bank of the Doumé River, 40 km SW of Batouri, near village Bimba, 15 Apr 1962 (fl, fr), Breteler 2797 (A, BR, FI-T, K, M, P), Southwest, Korup National Park, P transect, P plot, subplot 20F, 5°01'N, 8°48'E, 100 m, 10 Mar 2004 (fl), van der Burgt 662 (K); Prov. Southwest, along Lobe River near Ekondo Titi, 4°36'N, 9°00'E, 28 Feb 1987 (fl), Doumenge 313 (MO); 8 km W of Masok, 400 m, 27 Mar 1965 (fl), Leeuwenberg 5217 (B, DSM, K, L, MO, P, W, WAG-2 sheets); 10 km à l’Ouest de Bagodo, 28 Jul 1966 (fr), Letouzey 7563 (K, P); Mayo Banyo, 20 km NNE of Banyo, 8 Jun 1967 (fl), Letouzey 8552 (leg Mpom Benoit (K); Colline de Mill (5 km NE Lolodorf), 26 Jan 1974 (fl, fr), Letouzey 12797 (P); Bamenda, Fonfuka [6°31'N, 10°26'E], 3000-3500', May 1931 (fl), Maitland 1731 (K); Southwest, Three-corners Foe, 04°33'N, 09°04'E, 100 m, 28 Jul 1986 (fr), Mambo & Thomas 97 (G, MO); Ebolowa-Jaünde, Jan 1914 (fl), Mildbraed 7716 (K); etwa 180 km NW Jaunde, May 1914 (fl), Mildbraed 8422 (K); Mbüssa, 8-900 m, 6°N, 14°20'E, 29 Apr 1914 (fl), Mildbraed 9069 (K-2 sheets); South West Province, Mount Cameroon, Njonji, 4°07'N, 9°01'E, 420 m, 18 Apr 1997 (fl), Nning 364 (MO); Ngoasik (10 km SSE Ambam), rive du Ntem, 1 Mar 1963 (fl), Raynal & Raynal 10130 (P, W); Bertoua-Batouri, 1962 (fl), Tchinaye 113 (P); Korup Reserve, [ca. 4°59'N, 8°51'E], 12 Jan 1979 (fl), Thomas 595 (K); Southwest Province, Korup National Park, 5°03'N, 8°48'E, 50 m, 28 Feb-3 Apr 1984 (buds), Thomas 3242 (MO); Lombe Camp, Tissongo Study Area, Douala-Edea Reserve, Jun 1976 (fr), Waterman & McKey 809 (K); ca. 10 km SW of Ambam, S of Ebolowa, on N bank of Ntem River, 2 Mar 1964 (fl), de Wilde & de Wilde-Duyfjes 2043 (B, K, MO); ca. 50 km S of Badjob, ca. 60 km NW of Eséka, along the Njong River, 20 Mar 1964 (fl), de Wilde & de Wilde-Duyfjes 2172 (B, K, MO, PRE, WAG); bank of Nyong River, near the new bridge, ± 65 km SSW of Eséka, ± 200 m, 16 Jun 1964 (fr), de Wilde & de Wilde-Duyfjes 2703 (B, K, MO, WAG-2 sheets); about 10 km S of Meiganga, ca. 900 m, 23 Nov 1964 (fr), de Wilde et al. 3994 (WAG-2 sheets); region M’Bamileke [ “M'Bamileleke”], 19 Dec 1957 (fl), de Wit 352 [de Wit Herbarium 7952] (WAG-2 sheets). CENTRAL AFRICAN REPUBLIC. Oubangui, Rég. E Yango, Feb 1920 (fl), Adjt. Allouette s. n. [herb. De Ch. d’Alleizette] (L); Sangha Economique Prefecture, Ndakan, gorilla study area Njéké from M 5400 to C 5800, 16°12'N, 02°21'E, 350 m, 7 May 1988 (fl), Harris & Fay 607 (K, MO); Yalinga, 30 Mar 1921 (fl), Le Testu 2605 (BM, P, US); entre Yalinga et Bria (km 60), Guyao, 29 Apr 1921 (fl), Le Testu 2681 (BM, BR, MO-2 sheets); Yalinga, Haut Ubangi, 16 Mar 1923 (fl), Le Testu 4617 (BM, MO, P); Yalinga, 30 Apr 1923 (fl), Le Testu 4702 (BM); Yalinga, 25 Feb 1921 (fr), Le Testu s. n. (BM); bank of the Sangha River (international frontier) collected 30 km from Libongo southwards, 02°30'N, 16°04' E, 350 m, 27 Jul 1987 (fl), Thomas & Fay 7281 (MO, WAG); dans les roches Riv. Yakumburu 35 km E Moroubas, 1 May 1922 [1921 on P sheet, mai 1923 in Tisserant and Sillans 1953] (fl), Tisserant 476 (BM, P); Riv. Dakpete 30 km E Moroubas, 1 Apr 1924 (fl), Tisserant 1470 (BM); Bozoum, 1 May 1932 (buds), Tisserant 3068 (BM). SOUTH SUDAN. SW Equatorial Province, Aloma Plateau, ca. 1 mile SSW of Iwatoka, 23 Mar 1939 (fl), Hoyle 823 (BM, K); Korobe Forest, Yei District, Equatoria, 2 Jul 1958 (st), Jackson 3894 (K); am Nabambim, 19 Feb 1870 (bud, fr), Schweinfurth 3032 (K); Lado, Yei River, Asugi, 23 Oct 1919, Sillitoe 353 (K); Lado, Yei River, 10 Nov 1919 (fl), Sillitoe 479 (K). GABON. Estuaire: 8 km N of Libreville, 30 Jan 1961 (fl), Hallé 961 (WAG); forêt de la Mondah, 0°33'N, 9°23'E, 19 Dec 1993 (fl), Jongkind & Breteler 1329 (MO-2 sheets); ca. 1 km sur petite piste à droite, 2 km avant Cap Estérias, 12 Nov 1982 (fl), Louis 97 (WAG-2 sheets); N of Libreville, ca. 10 km on road to Cap Esterias, 0°30'N, 9°22'E, 10 m, 20 Nov 1991 (fr), McPherson 15526 (MO); ca. 20 km N of Libreville, 0°35'N, 9°22'E, 29 Jan 1987 (fl), Reitsma & Reitsma 2862 (MO, NY, RSA); Cap Esterias, Forêt de la Mondah, marsh forest, 10 m, 0°36.7'N, 9°23.3'E, 23 Oct 1994 (fr), Wieringa et al. 2884 (WAG); about 14 km along the road Libreville to Cape Esterias, 26 Nov 1983 (bud), de Wilde et al. 785 (MO).- Ngounié: Waka, forest exploitation road near what is called the Falaise, ca. 400 m, 1°18'S, 10°57'E, 22 Nov 1964 (fl), Arends et al. 389 (MO, P).-Nyanga: Doudou Mountains, 8 Dec 1984 (fl), Arends et al. 708 (MO, P, WAG).- Ogooué-Ivindo: Ile de l’éléphant, Makokou, 21 Sep 1971 (fl, fr), Hladik 1540 part A and part B (P); Ile de l’éléphant, pointe nord Makokou, 20 Jan 1972 (fl), Hladik 1924 part A (P); Ipassa, 10 km S of Makokou, small island in Ivindo River, 500 m, 20 Jan 1972 (fl), Hladik 1924 part C (US).- Ogooué-Maritime: SE of Port Gentil, ca. 0°40'S, 8°50'E, 16 Sep 1968 (fr), Breteler & van Raalte 5564 (WAG); Rabi-Kounga, ca. 1°55'S, 9°55'E, 25 Dec 1991 (fl), Breteler & Jongkind 10111 (WAG); 1 km on the road from Rabi to Divangui, along track, 1°54'S, 9°53'E, 25 Nov 1989 (fl), de Wilde et al. 9740 (WAG); Gamba, 19.5 km Gamba airport road to Mayonami, then 5 km along track to Nyanga River, ca. 2°56'S, 10°12'E, 23 Nov 1994 (fl, fr), de Wilde & de Wilde-Bakhuizen 11194 (WAG).-Woleu-Ntem: région entre Ogooué et Cameroun, bords de la Kyé, à Méyo’, 12 Mar 1933 (fl), Le Testu 9025 (BM, P); Bélinga, 19 Dec 1964 (fr), Hallé 3545 (P). REPUBLIC OF THE CONGO. Environs de N’tiétié, à 13 km du village vers N’Gongo, 9 Dec 1974 (fr), Sita 3813 (P). DEMOCRATIC REPUBLIC OF THE CONGO. Bas-Uele: Tukpwo, galerie de la Diagbo, 22 Nov 1954 (fr), Gerard 1611 (BR).-Haute-Uele: without definite locality [probably vicinity of Doruma], (fr), de Graer 241 (BR); Province Orientale, District Haut Uele, Territoire Dungu, Region Doruma, 4 Feb 1958 (fr), Leclercq 346 (BR).-Ituri: Epulu, zone de Mambasa (Ituri), 1°25'N, 28°35'E, 750 m, 12 May 1981 (fl), Hart 68 (K); Epulu, zone de Mambasa (Ituri), 1°25'N, 28°35'E, 750 m, 12 May 1982 (fl), Hart 284 (K).-Mai-Ndombe: entre Kole et Dekese (Lac Leo II), Oct 1932 (fl), Lebrun 6447 (K, P); Kutu (Lac Leo II), Nov 1932 (st-old pedicel), Lebrun 6599 (MO).-Tshopo: Yangambi, 7 Mar 1958 (fl), Leonard 247 (BR); Yangambi, plateau de la Lusambila, 8 May 1936 (fr), Louis 1842 (BR); Yangambi, embouchure Isalowe, 25 Mar 1938 (fl), Louis 8620 (RSA); Yangambi, au borde de la rivière Isolowe, Jul 1938 (fl), Louis 10255 (B, MO, NY, US); Yangambi, au bord de l’Etehwa, Oct 1938 (fl), Louis 13217 (BM, K-2 sheets, P); Yangambi, près de la rivière Lusambila, 12 Jan 1961 (fl), Yafunga F.60 (BR).-Province unknown: am Mbowole [I. Darbyshire, personal communication, indicates that this locality is in present-day Democratic Republic of the Congo], Mar 1870 (fl), Schweinfurth 3234 (K); ANGOLA. Lunda: Vila Henrique de Carvalho (Saurimo), pr. rio Chicapa, 1015 m [1050 m on MO sheet], Apr 1937 (yg fr), Gossweiler 11650 (BM, K, MO); nordeste de Lunda, Dundo, proximum flumen Luachima, 3 Sep 1946 (fl), Gossweiler 13648 (BM-2 sheets, K, US); nordeste de Lunda, circunscrição de Chitato, Marhura, river Chicapa, 700 m, 17 Jun 1948 (fl), Gossweiler 14110 (BM, K).

Xylopia thomsonii is a lianescent shrub or occasionally a small tree occurring in lowland forests, usually near wetlands. Within the Xylopia acutiflora subgroup, the species can be distinguished by the broadly cuneate to rounded leaf base, narrow petals variable in length but with the outer petals significantly longer than the inner petals, and slightly torulose blunt-tipped monocarps with up to 9 seeds in a single row. Indument of the twigs varies from a mixture of erect long and short hairs to short hairs only, the latter occurring primarily in specimens from coastal Gabon and Cameroon. The type specimen of X. thomsonii has some axils with two flowers, and the original description of the species indicates up to 20 carpels per flower. In our material, the inflorescences usually consisted of a single flower and the flowers never had more than 13 carpels. Even segregated from X. acutiflora , there is variability in this widespread species.

The range of X. thomsonii overlaps with that of X. unguiculata in the southern part of its distribution, and approaches that of X. monticola along the border between Cameroon and Nigeria. Xylopia unguiculata can be distinguished by the cuneate rather than rounded leaf bases, the broader outer petals, and the claw-like beak of the monocarps. In addition, the pedicels of X. unguiculata are shorter and the monocarps more strongly torulose. Xylopia monticola does not exhibit the liana habit and has monocarps with fewer seeds and proportionately longer stipes.

For a frequently collected species, little is known about the biology of X. thomsonii . The label of Léonard 247 from Democratic Republic of the Congo described it as occurring in forest of Scorodophloeus along water but no additional details were given.

The type of X. pyrifolia Engler at B, figured in Engler and Diels (1901, Plate XXII, Fig. B), consists of branches with leaves and one fruit of immature monocarps borne on a short pedicel. The leaves, while proportionately broader than is typical for X. thomsonii , have the same texture and rounded base. The monocarps, while immature, have a short stipe, blunt apex, and a single row of 2-4 seeds, all typical for the species. More problematic is the name Xylopia tenuifolia . The type specimen appears to be lost, but Engler and Diels (1901) placed it as a synonym of Xylopia oxypetala . The description agrees with that of X. thomsonii in the relatively thin oblong to elliptic-oblong leaves 10-13 cm long with few hairs and the usually solitary flowers, and the type locality in coastal Cameroon is plausible for X. thomsonii . Although the type specimen of Xylopia seretii comes from the northeastern extreme of the distribution, it agrees well with other specimens of X. thomsonii from that area.

Figures

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.

Figure 39. Xylopia thomsonii, X. monticola, X. talbotii, and X. dinklagei. A-C X. thomsonii A Fruit B Leaf C Flower D-E X. monticola D Flower E Leaf and fruit F X. talbotii, flower, side view G-I X. dinklagei G Leaf H Flower I Fruit. A from de Wilde & de Wilde-Duyfjes 2703 (K) B, C from Talbot & Talbot 3267 (BM) D from Chapman 3755 (K) E from Thomas et al. 7400 (MO) F from Thomas 3204 (MO) G, H from Dinklage 1840 (A) I from Baldwin 10805 (K).