Costus kupensis Maas & H.Maas, 2016

Maas-van de Kamer, H., Maas, P. J. M., Wieringa, J. J. & Specht, C. D., 2016, Monograph of African Costaceae, Blumea 61 (3), pp. 280-318 : 300

11. Costus kupensis Maas & H.Maas , sp. nov. — Fig. 5; Plate 3a; Map 6

Terrestrial herb 1.5–3 m tall. Leaves many; sheaths 1–2.5 cm diam, dark red; ligule chartaceous, 2-lobed, 5–18 mm long; petiole 5–10 mm long; sheaths, ligule and petiole rather densely covered with appressed to erect hairs <1 mm long; lamina narrowly obovate-elliptic, 20–27 by 6–9 cm, upper side glabrous, lower side sparsely to rather densely covered with erect hairs <1 mm long on margin and midrib to glabrous, base acute, apex acuminate (acumen 15–20 mm long). Inflorescence many-flowered, ovoid, 4–9 by 3–4 cm, terminating a separate leafless shoot 3–15 cm long; (upper part of) bracts and capsule sparsely to rather densely covered with appressed to erect hairs <1 mm long, bracteole with a row of erect hairs on the keel, calyx glabrous. Flowers 1 per bract; bracts dark reddish brown, coriaceous, broadly to depressed ovate, 1–2 by 1.5–2.5 cm, callus sometimes present and then c. 2 mm long; appendages absent; bracteole boat-shaped, 18–22 mm long, callus c. 1 mm long; calyx 12–16 mm long, in fruit exceeding the bracts, lobes narrowly to broadly triangular, 2–5 mm long, callus absent; corolla yellow, upper part of lobes pinkish, 55–60 mm long, glabrous, tube c. 15 mm long, lobes narrowly elliptic, 40–45 mm long; labellum yellow, with dark yellow nectar guide, funnel-shaped to horizontally flattened, broadly obovate when spread out, c. 50 by 50 mm; stamen yellow, c. 40 by 14 mm, apex recurved, anther 7–8 mm long. Capsule ellipsoid, c. 11 by 6 mm. Seeds c. 2 by 1.5 mm.

Distribution — Central Africa ( Cameroon).

Habitat & Ecology — In rainforest. At elevations of 800– 1000 m. Flowering and fruiting: January, May and October.

IUCN Conservation Status — Based on an EOO of 1419 km 2 and an AOO of 12 km 2, occurring on 3 locations, none of which currently has a protected status and one might be already lost, we assess this species as Endangered (EN) B1ab(i,ii,iii,iv,v)+ 2ab(I,ii,iii,iv,v).

Other specimens examined. CAMEROON, Littoral Province, Ebo proposed National Park, Yingui , CRES camp on trail to Iboti , 800 m, 23 Apr. 2005, Cheek et al. 12498 (K, YA); Mont Nlonako, 5 km SSE of Nkongsamba, 1000 m, 17 Mar.1976, Letouzey 14456 (K, P) . South-West Province, Kupe- Muanenguba Division, Kupe Village, vicinity of saprophyte site on Daniel Ajang’s bush, 870 m, 20 May1996, Cable et al. 2471 (K, U, WAG, YA) .

Note — The description is partly based on our observations on a living plant in Burgers’ Bush, vouchered as Maas & Maas 10575.