Renealmia montana 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 : 74

Renealmia montana Dhetchuvi & Eb.Fisch. , sp. nov. ( Figs 15–17 , 31 ).

Type: —D.R. CONGO. Forestier Central , Kivoe , Irangi, IRSAC-domein bij de rivier Luhoho ; 12 March 1972, P. van der Veken 9744 (BR0000020217976!) .

Diagnosis: —The new species ressembles Renealmia timmiorum but differs in the secund arrangement of flowers and fruits that are bent downwards (vs. flowers and fruits horizontally arranged or bent upwards, in spiral arrangement in R. timmiorum ), the shape and colour of the calyx and the fruits (elliptic to pear-shaped, green, black at maturity, calyx purple in R. montana vs. elliptic, red-orange, shining black at maturity, calyx red-orange in R. timmiorum ).

Description: —Perennial herb usually with few single shoots. Leafy shoots 40–100 cm tall, covered at base with imbricate leafless sheaths, upper sheath sometimes with reduced lamina. Leaves with sulcate sheaths surrounding stem, with reticulately anastomosing venation and densely pubescent between reticulations, with numerous simple and bifid hairs, margin membranaceous, reddish. Petiole 3–7 cm long, with reticulation and hairs within furrows. Ligule very short, up to 2 mm long. Lamina narrow-lanceolate, distinctly and progressively attenuate at base and decurrent at apex of petiole, acuminate to acute at apex, 14–18 cm long and 3.5–4.0 cm wide, median vein reticulate and glabrous, dark green at upper surface, greyish-green at lower surface, lateral veins visible only at lower surface. Inflorescence thyrsic, arising at base of leafy shoots, with flowers and fruits bent downwards, in secund arrangement, 20–36 cm long, entirely pubescent; peduncle about 17–25 cm long, up to 7 internodes reaching 8.5 cm of length, longer than sheaths, with basal leafless sheaths short and dense, upper sheaths longer, of about 7 cm length, with bifid and caducous hairs at outer surface, rachis 5–10 cm long, entirely purple, with minute simple and caducous hairs, glabrescent. Bracts coriaceous to membranaceous, persistant, lanceolate, basal bract 2.5–3.0 cm long, upper bracts shorter, glabrous with membranaceous ciliate margin, bracts of secondary axes lanceolate, with membranaceous ciliate margin, 1–2 cm long; bracteoles membranaceous, about 6–8 mm long, glabrescent; partial inflorescences (cincinni) subsessile, with 1(–2) flowers, peduncle about 2 mm long; pedicels purple, becoming orange in fruit, glabrescent, about 5–20 mm long. Calyx persistent, accrescent in fruit, tubular, glabrous except for ciliate margin, purple, about 6 mm, 1 cm long in fruit. Corolla white with purplish to violaceous marks, upper petal rounded, 5 mm long, tinged with mauve, labellum white with purple, about 8 mm in diameter, free portion 3-lobed, lateral lobes purplish. Stamen with 1 bilocular theca, about 2 mm long. Ovary 2–3 × 1–2 mm, glabrescent, greenish-yellowish tinged with purple, style 8 mm long, stigma bilobed. Fruits elliptic to pear-shaped, glabrous, about 16 mm long and 5 mm wide, green, shining black at maturity. Seeds red-orange, surrounded by yellowish aril, 2–3 per locule.

Distribution: —Only known from the Western crest of the Albertine Rift W of Lake Kivu.

Habitat: —Submontane to montane rainforest, 850–1650 m.

Etymology: —The specific epithet refers to the montane habitat compared to the predominantly lowland species.

Preliminary IUCN conservation assessment: — Renealmia montana is known from six locations in Eastern D.R. Congo. One of these is probably already destroyed as the Irangi Forest Reserve has almost been logged completely. The status of the other populations is not known. The extent of occurrence (EOO) falls within the limits for the Vulnerable status under sub-criterion B1. This loss of forest patches as a major threat leads us to predict a continuing decline in extent and quality of habitat, as well as number of mature individuals. By considering this threat, the species occurs at six locations, where all individuals can be severely affected by it. Based on the above observations, R. montana is listed as Vulnerable (VU).

Notes: — Dhetchuvi (1996) proposed a new species, Renealmia montana with a broad circumscription, occurring in the Eastern D.R. Congo and Rwanda. However, this proposed taxon consists of two different species, Renealmia timmiorum from Rwanda, and R. montana from Eastern D.R. Congo. For differences between the two species, see the diagnosis above.

Additional specimens seen (Paratypes): —D.R. CONGO. Forestier Central , entre Walikale et Kalehe (Kivu), March 1931, J. Lebrun 5271 (BR0000020217921, BR0000020217938) ; Kembe, Terr. Walikale , 11 May 1958, A. Léonard 1542 (BR0000020217969) ; Bukondo, Bunyakiri, Terr. Kalehe , 19 September 1957, R. Gutzwiller 2016 (BR0000020217945) ; Bukondo, Bunyakiri, Terr. Kalehe , 12 September 1957, R. Gutzwiller 1427 (BR0000020217983) ; Prov.: Kivu., Territ.: Kalehe . Route Kavumu-Walikale , vers Km 110, environ d’Irangi , Catena II, 20 m, 8 February 1958, G. Troupin 9283 (BR0000020217990) ; Irangi, October 2017, B. Dumbo s.n. (KOBL). Lacs Edouard et Kivu, Kikoma, Terr. Masisi , 26 April 1958, R. Gutzwiller 1641 (BR0000020217860) ; Keco, Terr. Masisi , 18 February 1959, A. Léonard 3128 (BR0000020217907) .

Figures

FIGURE 15. Renealmia montana. Holotype, BR. Reproduced with permission from BR.

FIGURE 16. Renealmia montana. A–D. Details of infructescence. A from Van der Veken 9744; B–D from Dumbo s.n. Photographs: B. Dumbo. Scale bar: A. 1 cm. Reproduced with permission from BR.

FIGURE 17. Renealmia montana. A, B. Leaves. C, D. Detail of infructescence. A–C from Van der Veken 9744; D from Dumbo s.n. Illustration by E. Fischer. Scale bars: A, B. 3 cm; C, D. 1 cm.

FIGURE 31. Distribution of Renealmia montana.