2.

Figs 1 B, 2

Type

GABON – Woleu-Ntem • Minkébé region, Nsye valley; 1°30’N, 12°49’E; 23 Feb. 1990; Wieringa 617; holotype: WAG [WAG.1338914]; isotypes: BR [BR 0000016245433] image, C n. v., K [K 005272502] image, LBV, M n. v., MO [MO-4496777], PRE n. v., WAG [WAG.1338915].

Diagnosis

Tragia flagellata is morphologically close to T. liberica Jongkind, but differs mainly by having unisexual inflorescences (vs bisexual inflorescences), and the calyx of female flowers (seen in fruit) with triangular and entire sepals (vs calyx of female flower with pinnatisect sepals).

Description

Twining perennial herb or shrub up to 5 m high; young branches pubescent with curved, appressed hairs up to 0.5 mm long; mature branches glabrescent. Stipules triangular-lanceolate, 3–4.5 × 0.8–1.1 mm, acuminate, sparsely hairy externally, with hairs up to 0.3 mm long, not ciliate. Petioles 0.6–1.7 cm long, densely pubescent with curved, appressed hairs up to 0.5 mm long; proximally pulvinate. Leaf blade elliptic to obovate, 7.5–14 × 2.5–4.5 cm, rounded at base, acuminate at apex, with acumen up to 1 cm, entire to slightly dentate, upper surface subglabrous, with simple subulate hairs up to 0.5 mm long and with stinging hairs up to 0.8 mm long mainly on veins; lower surface pubescent with stinging hairs up to 0.8 mm long on veins and up to 0.5 mm long on the lamina; basal veins 3–5, secondary veins in 7–8 pairs. Inflorescences unisexual. Male inflorescence up to 16.5 cm long; peduncle 8–9 cm long, densely pubescent with curved hairs up to 0.2 mm long that extend to the rachis; bracts narrowly triangular, 1.3–1.6 × 0.2-0.3 mm, sparsely hairy with hairs up to 0.1 mm long; bracteoles linear-lanceolate, 0.3–0.5 × 0.1 mm, subglabrous with few scattered hairs. Male flower pedicel 1.1–2.4 mm long, subglabrous with few scattered hairs; buds 0.4–0.5 mm diameter; calyx lobes broadly ovate to broadly elliptic, 0.7 mm long, pubescent externally; stamens 3; filament 0.15 mm long; anthers 0.2 × 0.15 mm. Female inflorescence up to 1.7 cm, peduncle up to 1.2 cm long, glabrescent, with 1–3 flowers; bracts ovate, 2 mm long, sparsely pubescent. Female flowers unknown. Fruits partially known; peduncle 3.5 mm long, pubescent; calyx lobes 6, triangular, up to 3.5 mm long, entire, slightly hardened when mature, sparsely pubescent with long thin hairs externally, with a distinct central vein; columella 3 mm long. Seeds unknown.

Distribution

Currently only known from Gabon, from the Woleu-Ntem and Ogooué-Ivindo provinces (Fig. 1 B).

Habitat and ecology

It grows in periodically inundated low forest (shrub vegetation behind riverbank) at ca 500–700 m elevation.

Etymology

The specific epithet, flagellata, is derived from the Latin flagellum (whip, scourge), and refers to the length of the male inflorescences and their whip-like resemblance.

Preliminary IUCN conservation assessment

Endangered: EN B 2 ab (iii). Tragia flagellata is known from two collections, made in 1966 and 1990, representing two occurrences and two subpopulations, which are both expected to be still extant. The area of occupancy (AOO) of this species is estimated as 8 km 2 (sensu IUCN 2022), which is below the upper threshold for a Critically Endangered status under subcriterion B 2. The extent of occurrence (EOO) cannot be calculated. The northernmost occurrence in the Nsye Valley (Wieringa 617) is situated at the limits of a mining concession, threatened by mining; the occurrence from Belinga (Hallé 422) is located in mining and forestry concessions, threatened by mining and logging. As a consequence, these two occurrences represent two locations concerning the most serious plausible threat (mining). We infer a current and future continuous decline in the extent and quality of its habitat. Tragia flagellata is thus provisionally assessed as Endangered: EN B 2 ab (iii).

Additional material examined

GABON – Ogooué-Ivindo • Bélinga, mines de fer, route du camp; [1°06’N, 13°12’E]; 11 Aug. 1966; Hallé 422; K [K 005272493] image, P [P 04839871], WAG [WAG.1339084].

Notes

Tragia flagellata is morphologically similar to Tragia preussii, another species from the surrounding countries (Cameroon and the Democratic Republic of the Congo). The collection Wieringa 617 was cited in the National Checklist (Sosef et al. 2006) as cf. T. preussii and this was the only record of this species in Gabon. Jongkind (2015) was the first author to suggest that this material could correspond to an undescribed species; he indicated that the female flowers are not in the same inflorescences as the male ones (like in T. volubilis). Here we confirm this character by reviewing all the available material (duplicates and one new collection found, Hallé 422). Tragia flagellata differs mainly by having unisexual inflorescences (vs bisexual inflorescences), and female flower calyx lobes triangular and entire (vs female flower calyx lobes deeply lobulate, with 3–4 lobes at each side).

This new species is still imperfectly known (female flowers and seeds are unknown, while fruits are partially known), but it is quite distinctive.