Tabernaemontana fragrans Jongkind, 2022

Jongkind, Carel C. H. & Lachenaud, Olivier, 2022, Novelties in African Apocynaceae, Candollea 77 (1), pp. 17-51 : 42-45

Tabernaemontana fragrans Jongkind , sp. nov. ( Fig. 14A, F ).

Holotypus: LIBERIA. Gbarpolu: 9 km E of Yoma, 20 km NE of Bomi Hills, fl., 6.VIII.1962, Leeuwenberg 4881 (2-part specimen: WAG [ WAG.1672632, WAG.1672633]!; iso-: B, BR [ BR0000014349065 ]!, EA, HBG, K!, MO, P [P04256880] image!, UC) .

Tabernaemontana fragrans Jongkind resembles T. psorocarpa (Pierre ex Stapf) Pichon in its climbing habit, relatively small flowers, and inflorescences with a distinct peduncle (0.5–4 cm long) but differs by its more narrowly ovoid fruits that are yellow to orange at maturity and angled to narrowly winged (vs. bumpy and pale bluish-green, not winged), its calyx lobes not longer than broad (vs. distinctly so) and its slightly larger corolla with a tube 13–18 mm long and lobes 13–20 mm long, the latter pubescent only on the left margin (vs. tube 9–14 mm long and lobes 7–17 mm long, the latter puberulous on both sides towards the base).

Lianas at least up to 20 m long, twining, latex white. Branchlets glabrous. Leaves of a pair equal or sometimes unequal, glabrous; blade 6–15 × 1.2–5.5 cm, elliptic to narrowly oblong, acute at base, acuminate at apex, dark green above, pale glaucous-green below; midrib prominent above; 6–9 pairs of hardly prominent secondary veins; tertiary venation inconspicuous; petiole 4–20 mm long. Inflorescences terminal (often becoming lateral due to sympodial growth of twigs) and usually paired, in umbelliform cymes, 3–10-flowered, glabrous; peduncle 5–40 mm long; bracts deciduous. Flowers 5-merous, with sweet scent; pedicel 8 – 19 mm long, glabrous. Calyces greenish, lobes round to broadly ovate, 2– 2.5 × 2–2.5 mm, ciliate. Corollas white, glabrous outside, in bud lobes forming are in bold. Note: we found the ovary of P. mutica to be occasionally 2-carpellate (Jongkind et al. 11771, Liberia) which has not been previously reported in the literature.

Pleiocarpa

Hunteria hexaloba Pleiocarpa mutica Pleiocarpa robusta Pleiocarpa rostrata picralimoides

Leaf blade [cm] 10.3–21 × 4.5–11.3 5–20 × 1.9–8 12–19 × 4–7.5 12.5–25 × 3.8–10.7 10.6–28 × 3.8–11.3

7–10 pairs,

9–12 pairs, weak Secondary veins prominent,

and almost straight strongly curved

Colleters inside

present absent

the sepals

11–18 pairs, 6–14 pairs, 7–12 pairs, weak, straight prominent, prominent,

or slightly curved strongly curved strongly curved absent absent absent

Corolla tube

6.5–7 10–22

length [mm]

Corolla lobes [mm] 7.5 × 1.8 4–13 × 1.7–4.3

around mid-height

Position of anthers near apex of tube of corolla tube

Style length [mm] 1.7–1.8 7.9–16

?

?

?

?

15–16 12–32

5–6 × 2–3 5.5–26 × 4–15

near apex of tube near apex of tube

c. 12 6.5–11

Ovary 2-carpellate (2–)3–5-carpellate 4–5-carpellate 3(–5)-carpellate 5-carpellate

Carpels c. 6-ovulate 1(–2)-ovulate c. 4-ovulate 1-ovulate 3–4(–6)-ovulate

Mericarp size

25–27 × 18–20 9–18 × 7–15 14–30 × 9.5–16 (9–)15–18 × 7–11 20–50 × 15–25

(dry state) [mm]

Mericarp apex acuminate acute to rounded acute acute beaked to rounded smooth (slightly finely verrucose smooth to strongly

Mericarp surface smooth verrucose wrinkled when dry) with domed warts verrucose Sierra Leone to NW coastal SW Gabon to SE Nigeria,

Distribution NW Gabon EC Gabon Gabon Cabinda Cameroon, EC Gabon [A: Leeuwenberg 12277, Côte d’Ivoire, spirit; B: Bidault et al. 3540, Gabon; C: Jongkind 12639, Liberia; D: Bidault 3540, Gabon; E: Jongkind 12639, Liberia; F: Bidault et al. 3274, Guinea] [Photos: A, C, E: C.Jongkind; B, D, F: E. Bidault]

a comparatively wide ovoid or subglobose head with a blunt apex; tube 13–18 × 4 mm, ± cylindrical with inflated base, slightly twisted or not, inside with rather sparse hairs from insertion of stamens to throat; lobes 13– 20 × 4 – 5.5 mm, lanceolate, ciliate on left margin, otherwise glabrous. Stamens included, inserted 3–4 mm above base of corolla tube; anthers c. 5 mm long, glabrous. Pistils 4–6 mm long, glabrous, reaching base of anthers; ovary cylindrical, c. 1.5 mm long, with two separated carpels; style c. 1.7 mm long, linear; pistil head 1.5–1.8 mm long, with a ring at base. Fruits of two separate and widely divergent mericarps, each up to 7 × 4.5 cm, narrowly ovoid and dorsoventrally compressed, with 3 narrow wing-like ridges, otherwise smooth, glabrous, yellow to orange.

Distribution, ecology and phenology. – This species is found in south-eastern Guinea, Liberia, Côte d’Ivoire and Ghana in forest up to elevations of 580 m ( Fig. 15A ). It is not known from the drier, semi-deciduous forests in Côte d’Ivoire and Ghana. Flowers have been collected mostly from June to December, once in March; fruits in November-December and March-April.

Conservation status. – The Extent of Occurrence (EOO) of Tabernaemontana fragrans is estimated as 129,500 km ², well above the threshold for “Vulnerable” status under Criterion B1. It is known from c. 19 subpopulations. Based on a 2 × 2 km cell size, its Area of Occupancy (AOO) is estimated as 60 km ², below the threshold for “Endangered” status under Criterion B2. The main threat to this species is from the ungoing clearance of forests for agriculture, plantations and mining in all four countries where it is found. A very substantial part of the forests in these countries is already gone (CILLS, 2016) and on several places where the species was collected there is no forest anymore today. However, the number of subpopulations is almost surely an underestimation since most of its range in Liberia is hardly explored. Tabernaemontana fragrans is known from several forest reserves and it is also likely to occur in protected areas like Taï National Park and Sapo National Park. It is also known to grow in secondary forests. The species is here assessed for the moment as “Near Threatened” [NT] because of the ungoing clearance of the forests, even in some of the protected areas, using the IUCN Red List Categories and Criteria ( IUCN, 2012).

Notes. – In the flowering stage this species closely resembles Tabernaemontana psorocarpa , and most of its collections were included by LEEUWENBERG (1991) in the latter, which was supposed to have a disjunct distribution between West and Central Africa. The fruits of West African specimens, treated here as T. fragrans , are however quite different from those of Central African specimens, including the type of T. psorocarpa ( Fig. 14A, B ), and there are also more subtle differences in the flowers ( Fig. 14D, F ). On the other hand, fruiting specimens of T. fragrans resemble T. glandulosa (Stapf) Pichon ( Fig. 14A, C ), the only other climbing Tabernaemontana species occurring in western Nigeria, which has much larger flowers ( Fig. 14E ). The differences between the three species are summarised in Table 6.

In the revision of Old World Tabernaemontana (LEEU- WENBERG 1991: 62, fig. 15) the depicted fruits of T. psorocarpa s.l. are mixed and presented as mature and immature fruits from the same plant. After studying the spirit material kept at WAG it became clear that the “immature” fruit in this illustration corresponds to T. fragrans (Leeuwenberg 12100) from Côte d’Ivoire, while the “mature” fruit corresponds to T. psorocarpa s.str. (J.J.F.E. de Wilde et al. 23/83) from Gabon. The photograph on the next page of the revision ( LEEUWENBERG 1991: 63, photo 3), showing fruits of Leeuwenberg 11440, is from another Tabernaemontana species, currently under study.

Additional specimens examined. – GHANA. Western Region: Subiri Forest Reserve, Daboase , 4.VI.1974, fl., Enti 1348 ( BR, WAG) ; Ankasa River Forest Reserve , 15.VII.1995, fl., Harder et al. 3462 ( MO, WAG) ; Axim , III.1934, fr., Irvine 2395 ( GC, K) ; Awiabo , XI.1928, fl., Vigne FH 1467 ( GC, K, P) .

CÔTE D’IVOIRE. Agnéby: 10 km E of Yakassé Mé, 15.IV.1980, imm. fr., Leeuwenberg 12100 ( BR, K, MO, PH, S, WAG) ; Forêt de Yapo , 2.XI.1981, fl. & fr., Leeuwenberg 12277 ( WAG) . Bas-Sassandra: 25 km SW of Guéyo, 29.III.1962, fl., Leeuwenberg 3774 ( BR, P, WAG) .

LIBERIA. Gbarpolu: Gola Forest , 1.XII.2005, fr., Jongkind et al. 7062 ( BR, WAG) ; Yeh River, 3.2 km above junction with St. Paul River , fl., 9.X.1926, Linder 999 (A, K, P) . Nimba: versant oriental Nimba, 9.X.1969, fl., Adam 24113 ( MO, P) ; route du Mont Tokadeh, 10.X.1971, fl., Adam 26262 ( MO, P) ; Yuelliton Road, 19.X.1964, fl., Adames 665 (K, P, UPS) ; Ganta, 17.IX.1947, fl., Baldwin 9300 (K, MO) ; Tappeta area , 19.IX.1965, fl., P.P. C. van Meer 175 ( BR, WAG) . Sinoe: E of Greenville-Zwedru road, 26.IX.2013, fl., Jongkind et al. 12158 ( BR, K, MO) ; N of Sapo National Park , 27.IX.2013, fl., Jongkind et al. 12167 ( BR, FHO, K, MO, P) .

GUINEA. Nzérekoré: Nimba Mountains , 23.IX.2017, fl., Bidault et al. 3274 ( BRLU, K, MO, P, SERG) ; Nimba Mountains, Forêt de Gbié , 17.XII.2008, fl., Haba & Bilivogui 19 ( WAG) ; Nimba mountains, near Tuo , 6.VII.2008, ster., Nimba Botanic Team WD 489 ( WAG) .

Figures

Fig. 14. – Fruit carpels of Tabernaemontana L.: A. Tabernaemontana fragrans Jongkind; B. Tabernaemontana psorocarpa (Pierre ex Stapf) Pichon. C. Tabernaemontana glandulosa (Stapf) Pichon. Flowers of Tabernaemontana: D. Tabernaemontana psorocarpa; E. Tabernaemontana glandulosa; F.Tabernaemontana fragrans.

Fig. 15. – Distribution maps. A. Tabernaemontana fragrans Jongkind (circles) and T. psorocarpa (Pierre ex Stapf) Pichon (triangles). B. Voacanga bracteata Stapf. C. Voacanga cornuta Jongkind (stars) and V. diplochlamys K. Schum. (circles).