Renealmia tenuis Dhetchuvi & Eb.Fisch., 2024

Fischer, Eberhard & Dhetchuvi, Jean-Baptiste M. M., 2024, A revision of the genus Renealmia (Zingiberaceae) in Tropical Africa. I. New species from Central Africa (Cameroon, Rio Muni, Gabon, Democratic Republic of the Congo), and notes on the identity of Renealmia africana, R. congolana, and R. dewevrei, Phytotaxa 674 (1), pp. 55-96 : 80-82

Renealmia tenuis Dhetchuvi & Eb.Fisch. , sp. nov. ( Figs 21–23 , 29).

Type: — GABON. Estuaire, 35 km S of Rabi, ± 13 m, partly flooded forest along the Echira River, predominantly sandy soil, 27 November 1989, J.J. de Wilde, J.C. Arends, Louis & J.J. Wieringa 9804 (holotype WAG 1868013!).

Diagnosis: —The new species resembles Renealmia stenostachys but differs in the cincinni with long peduncle and rachis bearing 3 flowers (1-flowered cincinni with very short peduncle in R. stenostachys ) and the linear-lanceolate leaves (ovate-lanceolate in R. stenostachys ).

Description: —Perennial herb forming dense clump, with aromatic scent. Leafy shoots 130 cm tall, covered at base with imbricate leafless sheaths. Leaves with sulcate, weakly coriaceous sheaths surrounding stem, with reticulately anastomosing venation and numerous minute red-orange hairs between reticulations. Petiole thin, longitudinally furrowed, c. 3 cm long, glabrous. Ligule obtuse, bilobed, up to 1.5 mm long, with few branched hairs outside. Lamina narrowly elliptic-linear, dull green, progressively attenuate at base and ± decurrent along petiole, narrowly acuminate at apex, about 16–25 cm long and 1.0– 2.5 cm wide, glabrous, median vein furrowed at lower surface, glabrous, lateral veins only visible at lower surface. Inflorescence thyrsic, arising at base of leafy shoots, small and lax, up to 65 cm long; peduncle about 20 cm long, with short and superposed sheaths of about 1–3 cm length, upper part of sheaths longer, c. 8 cm, glabrous, with internodes up to 12.5 cm length, glabrous. Bracts persistent, weakly coriaceous, lower ones c. 4 cm long, upper ones smaller, with small branched hairs at apex; bracteoles persistent, with few hairs at apex; partial inflorescences (cincinni) subsessile, with peduncle c. 1 cm long, with 3 flowers; pedicels about 15 mm long at lower flowers, shorter in upper flowers. Calyx persistent, accrescent in fruit, tubular, pinkish, about 7 mm. Corolla white, labellum white with yellow at gorge, about 8 mm in diameter, free portion 3-lobed. Stamen with 1 bilocular theca, about 3 mm long. Ovary 3 × 1–2 mm, glabrous, greenish-yellowish tinged with purple, style 8 mm long, stigma bilobed. Fruits not known.

Distribution: —Only known from the type collection from Rabi in coastal Gabon.

Habitat: —Partly flooded forest along the Echira River, predominantly sandy soil, 13 m.

Etymology: —The specific epithet refers to the delicate habit and inflorescence.

Preliminary IUCN conservation assessment: —With only one site where Renealmia tenuis has been observed, it is not possible to calculate the extent of occurrence (EOO). The area of occupancy (AOO) with 9 km ² meets the criteria of the Critically Endangered category (CR) under sub-criterion B2. One major threat is deforestation, and the only known location lies outside a protected area. There is only one herbarium sheet collected in 1989, which indicate that it is rare. The species is thus assessed here as Critically Endangered (CR B2).

Figures

FIGURE 21. Renealmia tenuis. Holotype, WAG. Scale bar: 5 cm. Reproduced with permission from WAG.

FIGURE 22. Renealmia tenuis. A, B. Detail of inflorescence. A, B from De Wilde et al. 9804. Scale bars: 5 mm. Reproduced with permission from WAG.

FIGURE 23. Renealmia tenuis. A, B. Leaves. C, D. Cincinni. A–D from De Wilde et al. 9804. Illustration by E. Fischer. Scale bars: A, B. 5 cm; C. 1 cm; D. 5 mm.