Renealmia longispicata Eb.Fisch. & Dhetchuvi, 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 : 67-70

Renealmia longispicata Eb.Fisch. & Dhetchuvi , sp. nov. ( Figs 10–11 , 28).

Type: —D.R. CONGO. Forestier Central, Riv. Lueme, 3 km en aval de Bokela, 21 March 1991, M.M. Dhetchuvi 1005 (holotype BRLU!).

Diagnosis: —The new species is morphologically similar to Renealmia polyantha but differs in the cincinni without peduncle and the cup-shaped bracteoles, and the ovate fruits (vs. cincinni elongate with distinct peduncle, bracteoles tubular-lanceolate, and fruits subglobose in R. polyantha ).

Description: —Perennial herb forming dense clump. Leafy shoots 60–100 cm tall, covered at base with imbricate leafless sheaths. Leaves with sulcate sheaths surrounding stem, without reticulately anastomosing venation. Petiole 4–6 cm long. Ligule obtuse, up to 5 mm long. Lamina oblanceolate, attenuate at base and decurrent along petiole, caudateacuminate at apex, about 20–28 cm long and 3.5–4.5 cm wide, greyish-green at lower surface, lateral veins visible at lower surface. Inflorescence thyrsic, arising at base of leafy shoots, 50–70 cm long; peduncle up to 35 cm long, with up to 5 leafless glabrescent sheaths of about 5–10 cm length, ciliate glabrous, rachis about ½ of inflorescence, glabrous. Bracts persistent, membranaceous, glabrous, about 3–16(–20) mm long; bracteoles persistent, membranaceous, glabrous, about 5 mm long; partial inflorescences (cincinni) subsessile, with 1 to 2(–3) flowers; pedicels red-orange, glabrous, about 4–5 mm long, regularly enlarged at apex. Calyx persistent, accrescent in fruit, tubular, glabrous except for ciliate margin, purple, 4 mm long, about 6 mm long in fruit. Corolla and stamen not known. Ovary 3–5 × 1–2 mm, glabrescent, greenish-yellowish tinged with purple, style 8 mm long, stigma bilobed. Fruits obovate, elongate, glabrous, shining black at maturity, 1.4 × 0.4–0.5 cm. Seeds globose-polygonal to irregular, 3 mm in diameter, 8–9 per locule.

Distribution: —Only known from Bokela in the central Congo Basin.

Habitat: —Swamp forest, 320– 370 m.

Etymology: —The specific epithet refers to the long spike-like thyrsic inflorescence.

Preliminary IUCN conservation assessment: —With only one site where Renealmia longispicata 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, as the only known location lies outside a protected area. However, the numerous specimens (18 herbarium sheets collected in 1991) indicates that the species is probably more abundant. It is thus assessed here as Data Deficiency (DD).

Additional specimens seen (Paratypes): —D.R. CONGO. Forestier Central, Riv. Lueme, 3 km en aval de Bokela, 21 March 1991, M.M. Dhetchuvi 974B (BR0000009475311), 975B, 976B, 978, 979, 980, 981, 982, 993, 998, 1006, 1007, 1002, 1003, 1004, 1009, 1014 (BRLU).

Figures

FIGURE 10. Renealmia longispicata. A. Holotype, BRLU. B. Detail of infructescence.A from Dhetchuvi 1005; B from Dhetchuvi 1010. Scale bars:A. 5 cm; B. 1 cm. Reproduced with permission from BRLU.

FIGURE 11. Renealmia longispicata. A, B. Leaves. C. Base of petiole with ligule. D–F. Cincinni showing bracts, bracteoles, and fruits. G. Fruit. A–C, F, G from Dhetchuvi 1009; D from Dhetchuvi 1010; E from Dhetchuvi 980. Illustration by E. Fischer. Scale bars: A–B. 5 cm; C–G. 5 mm.