Costus aureus Maas & H. Maas 2016, sp. nov.

4. Costus aureus Maas & H.Maas , sp. nov. — Plate 1b; Map 2

Costus aureus is characterized by flowers that are completely yellow and arranged in an inflorescence terminating a leafy shoot and composed of green and generally appendaged bracts. Vegetatively it looks very similar to C. lucanusianus by having a rim at the base of the ligule.However, this rim is hairless in C. aureus, while it is distinctly hairy in C. lucanusianus. —

Type: Berg 186 (holo U 4 sheets [U 0123675, U 0123676, U 0123677, U 0123678]; iso B, MO, NY), Ivory Coast, near Akoupé (NW of Abidjan), 31 July 1972.

Costus luteus A.Chev. (1920) 628, nom. illeg. non Blanco (1837) 4. — Type: Chevalier 17125 (lecto P,designated here), Ivory Coast,‘ Vallée de l’Agniéby à Guébo’, 31 Jan.1907; other syntype: Chevalier 17454 (LY, P), Ivory Coast, Attié, near Alépé, 26–28 Feb. to 1–3 Mar. 1907.

Terrestrial herb 0.5–3 m tall. Leaves many; sheaths 0.5–3 cm diam; ligule chartaceous, truncate, 1–5(–8) mm long, with a prominent glabrous rim at its base; petiole 5–18 mm long; sheaths, ligule and petiole sparsely to rather densely covered with erect to appressed hairs <1 mm long; lamina shiny on both sides, lower side dull greyish green, narrowly elliptic, rarely narrowly obovate, 15–30 by 4–8 cm, slightly plicate, margins often somewhat undulate, upper side sparsely covered with appressed hairs <1 mm long (mainly along midrib) to glabrous above, lower side sparsely to rarely rather densely covered with appressed hairs <1 mm long, base acute, the very base sometimes somewhat rounded, apex acuminate (acumen 5–20 mm long), sometimes acute. Inflorescence many-flowered, very broadly to depressed ovoid to subglobose, 3.5–7 by 4–8 cm, terminating the leafy shoot; bracts, appendages of bracts, bracteoles, calyx, ovary and capsule sparsely to rather densely covered with erect hairs <1 mm long to glabrous. Flowers 2 per bract; bracts green, coriaceous, broadly ovate, 1.5–2.5 by 1–2.5 cm, sometimes falling apart into separate fibers with age, callus absent; appendages mostly present, green, ascending, broadly ovate-triangular, 1–1.5 by 1–2 cm; bracte-ole boat-shaped, 15–20 mm long, callus 2–3 mm long; calyx 15–25 mm long, in fruit exceeding the bracts, lobes triangular, 2–7 mm long, callus absent; corolla yellow, 30–40 mm long, glabrous, tube c. 10 mm long, lobes narrowly elliptic, 20–30 mm long; labellum yellow, inner side with darker yellow nectar guide, horizontally flattened, broadly obovate when spread out, 40–45 by 35–40 mm; stamen yellow, c. 25 by 8 mm, apex darker yellow, anther 7–8 mm long. Capsule ellipsoid, 10–12 by 4–6 mm. Seeds 1.5–2 by 1–1.5 mm.

Distribution — West Africa (Ghana, Ivory Coast, Liberia).

Habitat & Ecology — In primary or secondary rainforest, often in wet places, on clay to sandy soil, at elevations of 0 – 600 m. Flowering and fruiting: all year through.

IUCN Conservation Status — Least Concern.

Selected specimens examined. GHANA, Ashanti Region, Distr. Sefwi Wiawso, Anhwiaso Forest Reserve, 1 Sept. 1984, Andoh FH 5241 (K); 10 miles S of Mampon(g), 8 Dec. 1953, Morton GC 9675 (K); Fumso, 24 Mar. 1950, Obeng-Darko 545 (K). Central Region, Wassa Atobiase,road to Rock Shrine, 70 m, 21 July 2010, Van Andel 5769 (GC, WAG). Western Region, Elubo, 22 km ESE towards Takoradi, 80 m, 14 July 1995, Harder 3435 (K, MO); Ankasa Game Reserve near entrance, 100 m, 28 Feb. 1995, Jongkind 2072 (MO, WAG); Ankasa River Forest Reserve, along dirt road to centre of reserve, 60 m, 30 July 2010, Van Andel 5865 (GC, L, U, WAG). – IVORY COAST, Banco Forest Reserve, 25 July 1975, W. J. van der Burg 673 (BR, FR, MO, UCJ, WAG); Vallée de l’Agneby à Guébo, 31 Jan.1907, Chevalier 17125 (P); pays de l’Attié, Alepe, 25 Feb. 1903, Chevalier 17454 (LY, P); Banco Forest Reserve, 11 Dec. 1972, De Koning 887 (BR, E, MO, WAG); km 25–30 on new road Abidjan-Ndouci, 21 Aug. 1979, De Kruif 305 (UCJ, WAG); Forêt de l’Angedédou, c. 15 km NW of Abidjan, 40 m, 3 Nov. 1958, Leeuwenberg 1874 (BR, F, K, UC, WAG); Forêt l’Anguédodou near Adiopodoumé, 25 Dec. 1957, H.C.D. de Wit 7850 (WAG). Aboisso, 2 km E of Maféré, near road to Afiénou, 50 m, 18 June 1975, Beentje 447 (AMD, UCJ, WAG); 12 km SE of Aboisso, 25 July 1968, Breteler 5297 (WAG). Adzopé, SOFALCO planta-tions, 2 km S of Adzopé, 100 m, 14 Dec. 1972, Leeuwenberg 10716 (WAG); Aouabo, 16 May 1969, Thijssen 21 (WAG). Agboville, Forêt de la Mambo, lisière Est de la forêt de Mambo, piste Albéric, 28 Jan. 1992, Chatelain 962 (CSRS, WAG); Gare des Makaugnié, Chemin de fer km 75, 22 Jan. 1907, Chevalier 16951 (P); Foret d’Yapo, 9 Oct. 1957, Farron s.n. (G). Danané, Danipleu region, 27 Mar. 1982, César 1716 (P); 20 km N of Danané, 18 Dec. 1967, Geerling 1862 (WAG). Guiglo, route de Tabou, near Siéblo Oula, 29 Dec. 1985, Aké Assi 17212 (G, MO); Forêt de Tai, near station, 21 Nov. 1982, C.C. Berg 1460 (U); Tienkoula, 4 Aug. 1962, Jangoux 255 (BR). Man, F.C. Scio, Pinhou, Lobykro, 2 Sept. 2001, Nusbaumer 693 (G). Sassandra, Along road from Dakpadou to Sago, N of Sassandra, 30 Mar. 1968, Geerling 2352 (WAG); on border of River Niegré, c. 64 km N of Sassandra near vil-lage Baléko, 16 June 1963, W.J.J.O. de Wilde 254 (WAG). Tabou, Tabou campment, 4 Sept. 1975, W. J. van der Burg 930 (WAG). – LIBERIA, Grand Gedeh, east slope of the Putu Hills East Range west of Tiama Town, 240 m, 25 May 2005, Jongkind 6379 (WAG); Putu Hills, East ridge, 628 m, 29 Sept. 2013, Jongkind 12192 (WAG). Maryland, Webo District, Nyaake, 24 June 1947, Baldwin 6126 a! (K). Montserrado, Firestone Plantation along Dukwai R., 170 m, 1 Nov. 1928, G.P. Cooper 14 (BM, F, GH, K, NY, P, US); New University Site, 30 km from Monrovia, 27 Sept. 1963, Harten 127 (WAG); Road Monrovia to Kakata, c. 13 miles from Monrovia,near Mount Barclay, 1 Feb. 1966, Van Meer 349 (WAG). Sino, road from Greenville to African Fruit Company, 27 July 1977, De Gier 13 (WAG); Sapo NP, buffer zone, around Safari Camp on short distance of Sinoe River, 115 m, 22 Nov.2002, Jongkind 5274 (BR, G, WAG); near Jalay’s Town, 29 Jan. 2016, Jongkind 12849 (BR).

Note — Costus luteus A.Chev. has a doubtful status. The introduction of the work in which it was published (Chevalier 1920) states that new names in that work are only mentioned and will be described later, but it is clear that they are nevertheless accepted, so art. 36.1 of the ICBN (McNeill et al. 2012) does not apply. However, often the names of this work are also not considered as validly published because the descriptions it contains are not recognized as such. But Chevalier often copies his own field descriptions when citing the specimens, which we consider as validating descriptions. In the case of C. luteus the name, when considered validly published, is a later homonym of C. luteus Blanco (nowadays Roscoea lutea (Blanco) Hassk.), and cannot be used in any case. However, to circumvent any discussion about the validity of Chevalier’s publication, we describe this species here independently as new and refrain from only using the nom. nov. construction. Because the name C. luteus had already been used, we name this yellow-flowered species C. aureus.