Tragia sericea I. Montero & Barberá, 2025

4. Tragia sericea I. Montero & Barberá sp. nov.

Figs 4 B View Figure 4 , 5 View Figure 5

Type

GABON – Ogooué-Maritime • Route en construction Port-Gentil-Omboué, env. 5 km au sud du pont sur l’Ogooué ; 1°05.22’S, 8°56.54’E; 26 Nov. 2016; Lachenaud 2354; holotype: P [ P 01193100 ]; isotypes: BR, BRLU, LBV, MO, WAG GoogleMaps .

Diagnosis

Tragia sericea is morphologically similar to T. zenkeri Pax , but differs mainly by having branches and petioles without stinging hairs (only appressed, curved, retrorse hairs) (vs branches and petioles with short and not stinging and stinging hairs), female flower with entire obovate bracts (vs subcuneate, regularly dentate in the upper third with 3 or 4 teeth on either side), and stipules ovate-cordate (vs stipules triangular-lanceolate).

Description

Twining perennial herb of unknown height; young and mature branches pubescent with retrorse, appressed hairs up to 0.3 mm long. Stipules ovate-cordate, ca 4.7 × 2.3 mm, acute, hairy externally, ciliate with hairs up to 0.5 mm long. Petioles 1.5–3.5 cm long, pubescent with curved, appressed hairs up to 0.3 mm long; distally and proximally pulvinate. Leaf blade elliptic to oblanceolate, (4 –) 5–8 × (2.2 –) 3–4.4 cm, cordate at base, acuminate at apex, with acumen up to 1 cm, subentire to slightly serrate, with few tufted hairs at the teeth apex, upper surface subglabrous, sparsely hairy with stinging hairs up to 0.5 mm long on the main veins, lower surface sparsely hairy with stinging hairs up to 0.5 mm long, densely on veins; basal veins 5, secondary veins in 4–5 pairs. Inflorescences bisexual, up to 4 cm long; peduncle up to 2 cm, pubescent with minute, curved, appressed hairs. Male segment up to (1 –) 1.5–2 cm long; bracts oblanceolate, 1.3 × 0.5 mm, sparsely hairy and ciliate with minute hairs; without bracteoles. Female segment with 2–3 flowers; bracts obovate, 1.7–2.1 × 1.7–2 mm, sparsely hairy externally with minute hairs, entire, ciliate with minute hairs; bracteoles lanceolate, 1.9 × 0.5 mm, sparsely hairy externally with minute hairs, ciliate with minute hairs. Male flower pedicel up to 1.5 mm long, sparsely hairy with few scattered hairs; buds to 0.9 mm diameter; calyx lobes 0.7 mm long, glabrous; stamens 3; filament ca 0.3 mm long; anthers 0.3 × 0.3 mm. Female flower subsessile; pedicel up to 0.4 mm long, pubescent with minute, curved hairs; calyx lobes 6, oblanceolate, entire, sometimes with a very small tooth near the base, 1.8 × 0.8 mm, sparsely hairy externally, ciliate with minute hairs; ovary 0.6 × 1.3 mm, densely hispid; styles up to 1.7 mm, connate until 2 / 3 to 1 / 2 of the length, sparsely hairy with minute hairs. Fruits on an up to 1.5 mm long peduncle, 4.5 × 6.5 mm, pubescent with stinging hairs up to 1 mm long, and not stinging too; calyx lobes up to 2.5 mm long, lobulate, laminula lanceolate, 1.3 × 1 mm, with 1–3 small linear sparsely hairy lobules on each side, hardened in the central part, sparsely hairy with very short hairs, ciliate; columella 2 mm long. Seeds 2 mm in diameter, black with yellowish patches.

Distribution

Equatorial Guinea, Gabon, and the Republic of the Congo (Fig. 4 B View Figure 4 ).

Habitat and ecology

It grows in littoral forest and other littoral vegetation, on white sand, at 10–21 m elevation.

Etymology

The specific epithet, sericea, is derived from the Latin sericeus (silky, silk), and refers to the lack of erect stinging hairs on the branches, which gives it a soft appearance.

Preliminary IUCN conservation assessment

Vulnerable: VU B 2 ab (iii). Tragia sericea is known from 11 collections made between 1897 and 2016, representing 10 occurrences and seven subpopulations. The area of occupancy ( AOO) is estimated as 36 km 2, below the upper threshold for Endangered status under subcriterion B 2. The extent of occurrence ( EOO) is calculated as 68,109 km 2, exceeding the upper threshold for “ Vulnerable ” status under subcriterion B 1. The occurrence from Equatorial Guinea is located close to the road and threatened by the road constructions. In Gabon, the two occurrences from the Estuaire province, from the surroundings of Libreville, are threatened by urbanisation; in the Ogooué-Maritime province, the northernmost occurrence is close to the road in construction from Port Gentil to Omboué and is threatened by road construction; the southernmost occurrence is located inside the Moukalaba-Doudau National Park, and it is not threatened; the four occurrences from the Nyanga province are included in the Gamba Protected Area Complex, but threatened by shifting agriculture. The two occurrences from Republic of the Congo from Kouilou province are threatened by shifting agriculture. As a consequence, these ten occurrences represent seven locations, concerning the most serious plausible threat (shifting agriculture). We infer a current and future continuous decline in the extent and quality of its habitat. Tragia sericea is thus provisionally assessed as Vulnerable: VU B 2 ab (iii).

Additional material examined

EQUATORIAL GUINEA – Litoral • Bata-Bome, pradera graminosa con longo do Rio Boara con ilhas arboreas arbustivas formadas pelas especies ; [ 1°45’N, 9°45’E]; 8 Oct. 1991; Carvalho 4867; MA [ MA-597380 ] GoogleMaps .

GABON – Estuaire • 8 km N Libreville ; [ 0°25’N, 9°27’E]; 30 Jan. 1961; Hallé 0969; P [ P 04839873 ] GoogleMaps • Environs de Libreville ; [ 0°25’N, 9°27’E]; 1897; Klaine 743; P [ P 04808441 ] GoogleMaps . – Nyanga • Gamba, Pont Dick, 3.6 km SW of Gamba airport ; 2°48.5’N, 10°02.8’E; 300 m; 29 Nov. 1994; de Wilde 11240; BRLU, E n. v., LBV, M n. v., MO [ MO-4496803 ], WAG [ WAG.1338861 , WAG.1338862 ] GoogleMaps • Near Ivinga 23 ; 2°48.00’S, 10°03.05’E; 31 Dec. 1990; van Nek 514; LVB, WAG [ WAG.1338856 ] GoogleMaps • Gamba, 4 km ESE of airport, road to radio mast ; 2°48.01’S, 10°04.07’E; 10 m; 19 Mar. 1994; Wieringa 2600; BR, G [ G 00351141 ], LBV, MA [ MA-859889 ], MO [ MO-4496804 ], P, W [ W 2013-0009087 ], WAG [ WAG.1338858 , WAG.1338859 , WAG.1338860 ] GoogleMaps . – Ogooué-Maritime • Side roads of road Pény-Mouila, in CBG concession ; 2°02.0’S, 9°25.5’E; 21 m; 10 Nov. 2011; Maas 10194; LBV, UC [ UC 2106923 ], WAG [ WAG.1339083 ] GoogleMaps .

REPUBLIC OF THE CONGO – Kouilou • Conkouati, Douli, forêt sur sable blanc a 200 m du village Vandji; [ 4°02’07.7”S, 11°15’46.9”E]; 3 m; 11 Dec. 2012; Mpandzou 1857; IEC n. v., K [ K 000609803 ] (image) • Plage Longo, Boudji; [ 4°18’28.9”S, 11°31’03.8”E]; 12 Dec. 2012; Mpandzou 1893; IEC n. v., K [ K 000609799 ] (image).

Notes

Specimens of T. sericea were previously identified as T. tenuifolia or T. laminularis , due to the similarity to those species. Tragia tenuifolia seems endemic to São Tomé and does not occur in Gabon, while T. laminularis occurs only in Ivory Coast and Liberia. The new species is morphologically similar to T. mildbraediana (see Notes with T. mildbraediana ).

All the specimens cited by Sosef et al. (2006) as T. laminularis ( de Wilde 11240, Nek 514, 735, Wieringa 2600) and T. tenuifolia ( Klaine 743) belong to T. sericea .