Costus gabonensis Koechlin
Creators: name: Kamer 1, H. Maas-van de
name: Maas 1, P. J. M.
name: Wieringa 1, J. J.
name: Specht, C. D.
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Liliopsida
Zingiberales
Costaceae
Costus
Costus gabonensis

description: <b> 8. <i>Costus gabonensis</i> Koechlin</b> — Plate 2b; Map 7 <i>Costus gabonensis</i> Koechlin (1964) 82, pl. 18, 1–5. — Type: <i>Le Testu 2240</i> (holo P; iso A, B, BM, BR, G, K, L [L.1480436], P), Gabon, Ngounié, Tsamba, 27 Oct. 1917. Terrestrial herb 0.5–2.5 m tall. <i>Leaves</i> several; sheaths 0.5–1 cm diam; ligule membranous, 2-lobed, 5–35 mm long; petiole 2–5 mm long; sheaths, ligule and petiole densely to sparsely covered with erect hairs to c. 5 mm long; lamina green, some-times purple-red at lower side, shiny at upper side, narrowly elliptic, 13–28 by 5–9 cm, upper side covered with stiff, erect hairs 1.5–2 mm long to glabrous, lower side sparsely to rather densely covered with soft erect hairs c. 1.5 mm long, base acute, obtuse to subcordate, apex acuminate (acumen 5–10 mm long). <i>Inflorescence</i> many-flowered, ellipsoid to ovoid, 5–9 by 2–4 cm, terminating a leafy shoot; bracts, appendages of bracts, bracteoles, calyx, ovary and capsule densely to rather densely covered with erect to appressed, white hairs &lt;1 mm long. <i>Flowers</i> 1 per bract; bracts white at base, greenish pink to red or purplish brown at apex, chartaceous, broadly obovate to obovate, 1–1.5 by 0.5–1.5 cm, callus absent; appendages pinkish red to purplish brown, strongly reflexed, narrowly trian-gular to triangular, 1–3 by 0.6–1.5 cm; bracteole boat-shaped 15–20 mm long, callus green, 1–3 mm long; calyx 9–10 mm long, lobes deltate to very shallowly triangular, 1.5–3 mm long, callus absent; corolla yellow to dark yellow, 40–50 mm long, densely to rather densely covered with (erect to) appressed, white hairs &lt;1 mm long, tube 10–20 mm long, lobes narrowly elliptic, 20–30(–40) mm long; labellum completely yellow, hori-zontally flattened, broadly obovate when spread out, 35–50 by 40–50 mm, margin irregularly lobed; stamen yellow, 35–40 by 7–10 mm, apex slightly orange, anther 7–8 mm long. <i>Capsule</i> obovoid, 9–10 by 6–7 mm. <i>Seeds</i> c. 3 by 2 mm. Distribution — Central Africa (Gabon). Habitat &amp; Ecology — In primary and secondary rainforest, at elevations of 300–1000 m. Flowering and fruiting: September to December. Field observations — The flowers of this species are quite aberrant from any other species of <i>Costus</i> in that they emit a strong scent reminiscent of jasmine (<i>A.M. Louis et al. 853</i>, <i>Van Valkenburg et al. 2649</i>). IUCN Conservation Status — Based on an AOO of 88 km 2 from about 14 locations of which only two are located in a protected area, while the others are located in areas currently being logged or face logging threats, we assess this species as Near Threatened (NT). H. Maas-van de Kamer et al.: Monograph of African <i>Costaceae</i> 299 ). Notes — <i>Costus gabonenis</i> is unique by its combination of bracts with reflexed red to purplish brown appendages, yellow flowers and a densely hairy corolla. It is endemic to Gabon and it superficially resembles the Neotropical <i>C. comosus</i> (Jacq.) Roscoe. The boat-shaped bracteole of <i>C. gabonensis</i> is 2-keeled to almost 2-winged presumably caused by the compactness of the inflorescence. The base of the shoot is red or purplish brown.
description: Published as part of <i>Kamer 1, H. Maas-van de, Maas 1, P. J. M., Wieringa 1, J. J. &amp; Specht, C. D., 2016, Monograph of African Costaceae, pp. 280-318 in Blumea 61 (3)</i> on pages 296-299, DOI: 10.3767/000651916X694445, http://zenodo.org/record/7570023