A taxonomic revision of Tragia (Euphorbiaceae) in Gabon, with a description of two threatened new species Montero-Muñoz, Iris Barberá, Patricia Plant Ecology and Evolution 2025 2025-09-29 158 3 367 381 I. Montero & Barbera I. Montero & Barbera 2025 Magnoliopsida Euphorbiaceae Tragia Plantae Malpighiales Tracheophyta species flagellata sp. nov.   Figs 1 B, 2   Type   GABON–  Woleu-Ntem• Minkébé region, Nsye valley;  1°30’N, 12°49’E;  23 Feb. 1990;  Wieringa617; 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 flagellatais morphologically close to  T. libericaJongkind, 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 herbor shrubup to 5 mhigh; young branches pubescent with curved, appressed hairs up to 0.5 mmlong; mature branches glabrescent. Stipulestriangular-lanceolate, 3–4.5 × 0.8–1.1 mm, acuminate, sparsely hairy externally, with hairs up to 0.3 mmlong, not ciliate. Petioles 0.6–1.7 cmlong, densely pubescent with curved, appressed hairs up to 0.5 mmlong; proximally pulvinate. Leaf bladeelliptic 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 mmlong and with stinging hairs up to 0.8 mmlong mainly on veins; lower surface pubescent with stinging hairs up to 0.8 mmlong on veins and up to 0.5 mmlong on the lamina; basal veins 3–5, secondary veins in 7–8 pairs. Inflorescencesunisexual. Male inflorescenceup to 16.5 cmlong; peduncle 8–9 cmlong, densely pubescent with curved hairs up to 0.2 mmlong 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 mmlong; bracteoles linear-lanceolate, 0.3–0.5 × 0.1 mm, subglabrous with few scattered hairs. Male flowerpedicel 1.1–2.4 mmlong, subglabrous with few scattered hairs; buds 0.4–0.5 mmdiameter; calyx lobes broadly ovate to broadly elliptic, 0.7 mmlong, pubescent externally; stamens 3; filament 0.15 mmlong; anthers 0.2 × 0.15 mm. Female inflorescenceup to 1.7 cm, peduncle up to 1.2 cmlong, glabrescent, with 1–3 flowers; bracts ovate, 2 mmlong, sparsely pubescent. Female flowersunknown. Fruitspartially known; peduncle 3.5 mmlong, pubescent; calyx lobes 6, triangular, up to 3.5 mmlong, entire, slightly hardened when mature, sparsely pubescent with long thin hairs externally, with a distinct central vein; columella 3 mmlong. Seedsunknown.   Distribution Currently only known from Gabon, from the Woleu-Ntemand Ogooué-Ivindoprovinces (Fig. 1 B).   Habitat and ecology It grows in periodically inundated low forest (shrub vegetation behind riverbank) at ca 500–700 melevation.   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: ENB 2 ab (iii).  Tragia flagellatais 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 flagellatais thus provisionally assessed as Endangered: ENB 2 ab (iii).   Figure 2.   Tragia flagellata. A. Habit. B. Leaf lower surface detail. C. Stipule and petiole. D. Male part of the inflorescence detail. E. Male bract and flower. F. Female inflorescence detail with columella. G. Fruit calyx. Drawn by Hilde Orye, Meise Botanic Garden, based on Wieringa 617( WAG.1338914, WAG.1338915).   Additional material examined   GABON–  Ogooué-Ivindo• Bélinga, mines de fer, route du camp; [  1°06’N, 13°12’E];  11 Aug. 1966;  Hallé422; K[ K 005272493] image, P[ P 04839871], WAG[ WAG.1339084].   Notes   Tragia flagellatais morphologically similar to  Tragia preussii, another species from the surrounding countries ( Cameroonand the Democratic Republic of the Congo). The collection Wieringa 617was cited in the National Checklist ( Sosef et al. 2006) as cf.  T. preussiiand 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 flagellatadiffers 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. 5830262365 1990-02-23 WAG, BR, K, LBV, MO Wieringa Gabon 1.5 Nsye valley 1308 12.816667 Minkebe region BR 0000016245433, K 005272502, MO- 4496777, WAG. 1338915 2 Woleu-Ntem holotype 5830262368 mines de fer, route du camp 1966-08-11 K, P, WAG Halle Gabon 1.1 Belinga 1308 13.2 K 005272493, P 04839871, WAG.1339084 1 Ogooue-Ivindo