Vepris africana (Lachenaud & Onana, 2021)

Lachenaud, Olivier & Onana, Jean-Michel, 2021, The West and Central African species of Vepris Comm. ex A. Juss. (Rutaceae) with simple or unifoliolate leaves, including two new combinations, Adansonia (3) 43 (10), pp. 107-116 : 109-112

Vepris africana (Hook.f.) O.Lachenaud & Onana, comb. nov.

( Fig. 1 ).

Glycosmis (?) africana Hook. f., Niger Flora: 256 ( Hooker 1849). —

Type: São Tomé & Príncipe. São Tomé, without precise locality or date (fr.), Don s.n. (holo-, K[ K000199556 ]).

Teclea gossweileri I.Verd. , Bulletin of Miscellaneous Information, Kew 9: 409 ( Verdoorn 1926), syn. nov. — Vepris gossweileri (I.Verd.) Mziray, Symbolae Botanicae Upsalienses 30: 72 ( Mziray 1992), nom. illeg. [non V. gossweileri I.Verd. ].—

Type: Angola. Cuanza Norte, Cabiri, 1.VII.1921 (male fl.), Gossweiler 8328 (holo-, K[ K000199528 , K000199529]).

DISTRIBUTION. — This species has a very scattered distribution in NW coastal Gabon (around Libreville), coastal Republic of Congo (mouth of Kouilou River), northern Angola, and the north of São Tomé island ( Fig. 2 ).

HABITAT. — Littoral thickets, edge of mangroves, and forest islands in savanna, often associated with rocky outcrops (especially of limestone), 0-1200 m in elevation; often gregarious, sometimes even dominant in its habitat.

PHENOLOGY. — Flowers collected in January, March to July , and September to November , probably all year round; fruits in November.

OTHER STUDIED MATERIAL. — Angola. Granja de S. Luiz, Cazengo , 21.XI.1917 (fr.), Gossweiler 5260 ( BM); towards Caçaça, Granja de S. Luiz, Cazengo, 9.XI.1919 (fl. buds), Gossweiler 5636 ( BM) ; Cassualala , Cuanza Norte, 22.V.1921 (male fl. buds), Gossweiler 8311 ( BM, P06600613 ); Cuanza Norte, Castendo , 16.X.1922 (bisexual fl.), Gossweiler 8437 ( BM, BR); Hochland von Quela, 1200 m, IX.1938 (male fl.), Nolde 827 ( BM).

Republic of the Congo. Bas-Kouilou , 2.I.1991 (st.), Dowsett-Lemaire 1496 ( BR); Bas-Kouilou, 19.IV.1991 (male fl. buds), Dowsett- Lemaire 1583 ( BR).

Gabon. c. 12 km NE of Libreville, Forêt de la Mondah , 0°33’N, 9°22’E, 28.I.1986 (male fl.), J.M. & B. Reitsma 1775 ( LBV, P06600589 , WAG); c. 6 km NE Malibé , 0°35’N, 9°26’E, 20.XII.1986 (fr.), J.M. & B. Reitsma 2742 ( LBV, WAG) ; North of Libreville on Cape Esterias road, 0°35’N, 9°25’E, 14.VII.1986 (male fl. buds), D.W. Thomas & Wilks 6350 ( LBV, WAG) ; Rivière Maliba , 26.III.1969 (male fl.), Villiers 54 (P06600612); Rivière Maliba, 11.VI.1969 (male fl.), Villiers 111 (P06600614); village Maliba, 23.IX.1969 (male fl.), Villiers 337 (P06600610).

São Tomé. near Morro Carregado, N coast, 0°25’N, 6°37’E, 13.II.1980 (fr.), J.J.F.E. de Wilde et al. 448 ( BR, WAG) ; chemin entre Plancas 1 et Ribeira Funda, 0°22.075’N, 6°35.784’E, 25.X.2019 (st.), Lachenaud et al. 2745 ( MO, STPH) ; côte Nord, c. 0,75 km à l’est de Lagoa Azul vers Morro Peixe, 0°24.379’N, 6°36.961’E, 28.X.2019 (fr. imm.), Lachenaud et al. 2768 ( BR, BRLU, COI, MO, STPH) ; without locality or date (fr.), Oliveira 1657 ( BRLU) ; Morro Barro Vermelho , 250 m, 10.I.1997 (st.), Oliveira F 33 ( BRLU) ; Lobata, Lagoa Azul, Imbondeiros , zona norte da Praia das Conchas , 9.III.2018 (fl. buds), Paiva et al. 288 ( COI) ; without locality or date (st.), Welwitsch 6762 ( BM) .

PRELIMINARY CONSERVATION ASSESSMENT. — Near-threatened. Vepris africana , comb. nov. is a shrub occurring in Central Africa (São Tomé, Gabon , Congo Republic and Angola ) in dry or littoral forest habitats, often on rocky outcrops, from sea level to 1200 m in elevation. It is known from 22 herbarium specimens, five of which were not taken into account for this assessment since their localities are either missing or untraceable. Based on the remaining 17 specimens, its extent of occurrence (EOO) is estimated to be 369480 km ² (far exceeding the limit for Vulnerable status under criterion B1) and its area of occupancy (AOO) to be 48 km ², within the limit for Endangered status under criterion B2. These collections represent twelve unique occurrences, eight subpopulations, and eleven locations in the sense of IUCN. Only one occurrence is protected in the Raponda-Walker Arboretum (Gabon), and most of the rest, especially in São Tomé and Gabon, occurs in areas where deforestation for agriculture, charcoal production, and urban expansion is strong, leading to an observed decline in the extent and quality of the habitat and number of individuals. The number of locations (eleven) is just above the limit for Vulnerable status under the conditions B2ab(iii,v), and because some of them are likely to disappear in the near future, the species is assessed as Near-threatened.

DESCRIPTION

Shrub

1-5 m high, much branched; all parts with slight citrus smell when crushed.

Twigs

Cylindrical, 2-2.5 mm thick, glabrous, soon covered with a pale grey bark, with scattered lenticels.

Leaves

Alternate or sometimes opposite near the apex of the twigs, unifoliolate, entirely glabrous; petiole 0.4-3(-5) cm long, canaliculate above, slightly bipulvinate, articulate at apex; lamina elliptic to slightly oblanceolate, 5.5-18.5 × 1.7-7.4 cm, cuneate at base, acuminate at apex, ± coriaceous, drying olive green to grey-brown; midrib slightly convex above; secondary veins 16- 23 pairs, weak and hardly distinct from the tertiaries, hardly ascending, forming regular arches 1-3.5 mm from leaf margin; tertiary and quaternary veins concolorous and prominent on lower leaf surface, the former parallel to the secondaries, the latter reticulate forming areolae c. 1 mm wide; glandular dots dense and rather conspicuous on lower leaf surface,2-5 per mm².

Flowers

Androdioecious.

Male inflorescences

Axillary on young leafy twigs, 3-6 cm long, paniculate with flowers borne in distant glomerules along divaricate lateral branches up to 3 cm long, the axes glabrous to puberulous; bracts ovate, minute, <0.5 mm long.

Male flowers

4-merous; pedicel absent or very short, 0-0.5 mm, glabrous; calyx cupular, 1-1.3 × 1-1.2 mm, truncate or with minute rounded lobes, glabrous except ciliolate margin; bud ellipsoid, c. 1 × 0.7 mm, rounded at apex; petals free, narrowly oblong, 2.5-3 × 0.7-1 mm, rounded at apex, glabrous, patent to reflexed at anthesis; stamens 4, glabrous, with linear filaments c. 1.5 mm long and elliptic anthers c. 0.6 × 0.4 mm; intrastaminal disk absent; pistillode c. 2.3 mm long, linear with inflated base, glabrous.

Bisexual inflorescences

Axillary and sometimes terminal on young leafy twigs, 0.5- 8 cm long, racemose or sometimes paniculate with short ramifications <0.5 cm long, with flowers condensed in ± distant glomerules along the axes, the latter with short and sparse patent hairs; bracts minute, triangular to ovate, c. 0.5 mm.

Bisexual flowers

4-merous, sessile; calyx cupular, 1.2-1.5 × 1.5-1.8 mm, truncate or with minute rounded lobes, glabrous except ciliolate margin; bud ellipsoid, c. 2 × 1.3 mm, rounded at apex; petals free or nearly so, narrowly ovate, 2-2.7 × 0.7-1.2 mm, rounded at apex, glabrous, patent to reflexed at anthesis; stamens 4, similar to those of male flowers but with thicker filaments; ovary 1-locular, subcylindrical, c. 1.5 × 0.8 mm, glabrous, the apex truncate with a broad sessile discoid stigma c. 0.8 mm broad.

Fruits

Orange, ellipsoid to subglobose, 6-12 × 6-8 mm when dry (up to 15 × 12 mm in life), smooth, glabrous, sessile, with persistent stigma; pericarp very thin, c. 0.2 mm thick when dry; endocarp thinly crustaceous, c. 0.2 mm thick; seed solitary.

REMARKS

Vepris africana , comb. nov. is unusual for the genus in being apparently androdioecious: in both types of flowers the anthers are present and produce normal pollen; the ovary is normally developed in bisexual flowers but reduced to a pistillode in male flowers. The species is very similar to V. unifoliolata (Baill.) Labat, M.Pignal & O.Pascal [syn. V. punctata (I.Verd.) Mziray ] from the Comoros and Madagascar, which appears to differ only in its truly dioecious flowers – the female ones lacking anthers – and glabrous calyx margin. The differences between the two taxa are rather slight, in spite of their wide geographic disjunction, and they might perhaps be treated as subspecies of a single species – in which case V. africana , comb. nov. is the older name.

The distribution of V. africana , comb. nov. is rather unusual, but no significant differences could be found between the collections from São Tomé (with fruits only), Gabon and Congo (with male flowers and fruits) and Angola (with fruits and both flower types). The occurrence of the species in São Tomé, a recent volcanic island never connected to the continent, probably originates from dispersal by frugivorous birds, or possibly by marine currents since the plant often grows near the coast. There is no reason to suspect an introduction by man, since it is not a ruderal plant and not reported to be cultivated.

The original publication of Teclea gossweileri ( Verdoorn 1926) does not specify the herbarium of deposit of the type, Gossweiler 8328. However, there appears to be only one specimen of this number in Kew (consisting of two sheets labelled Sheet I and Sheet II) which is therefore to be regarded as the holotype. No sheet of this number was found in BM, and Exell & Mendonça (1951: 271) report none from Portuguese herbaria, from which they studied the material for their treatment.

One of the Angolan collections(Gossweiler4799)referred to this species by Exell & Mendonça (1951, as Teclea gossweileri ) actually represents Vepris welwitschii ; see under that species. Differences between V. africana , comb. nov., V. laurifolia (Hutch. & Dalziel) O.Lachenaud , comb. nov. and V. welwitschii are summarised in Table 1 .

Figures

FIG. 1. — Vepris africana (Hook.f.) O.Lachenaud & Onana, comb. nov.: A, twig with male inflorescences in bud; B, petiole; C, portion of twig with bisexual inflorescences;D, detail of lower leaf surface showing venation and glandular dots; E, portion of inflorescence with male flower; F, same with bisexual flower; G, fruit; A, B, from Dowsett-Lemaire 1583; C, F, from Gossweiler 8437; D, G, from J.J.F.E. de Wilde et al. 448; E, from Nolde 827. Drawing: Antonio Fernandez. Scale bars: A, C, 4 cm; B, D, G, 5 mm; E, F, 2 mm.

FIG. 2. — Distribution map of Vepris africana (Hook.f.) O.Lachenaud & Onana, comb. nov. (·), V. laurifolia (Hutch. & Dalziel) O.Lachenaud, comb. nov. (●) and V. welwitschii (Hiern) Exell (▲).