Costus tappenbeckianus J.Braun & K.Schum. — Plate

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 : 311-312

24. Costus tappenbeckianus J.Braun & K.Schum. — Plate 3c; Map 10

Costus tappenbeckianus J.Braun & K.Schum. (1889) 152; K.Schum. (1904) 416. — Type: Braun s.n. (holo B destroyed), cultivated and flowering in April 1889 in the Hort.Bot.Berlin from material collected in Gross-Batanga, South Province, Cameroon. As the holotype in Berlin was destroyed and no other type material was located, we hereby select a neotype from a locality not far from the type locality: J.J.F.E. de Wilde 8702 (neo WAG 2 sheets [WAG0114484, WAG0114485]; isoneo BR, EA, K, MA, MO, P, PRE, YA), Cameroon, South-West Province, Dipikar Island, 3 km SE of the bridge crossing the Bongola River , along forest exploitation track, 3 Dec. 1975 .

Costus pauciflorus K.Schum. (1892) 421, syn. nov. — Type: Soyaux 119 (holo B destroyed; lecto K, designated here), Gabon, Estuaire, ‘in ditione Munda, Sibange-Farm’ , 3 Sept. 1880.

Costus radicans Gagnep. (1903) 262, syn. nov. — Type: Bates 519 (holo P; iso BM, G, K), Gabon, Estuaire, Mfôa , 85 miles E of Gaboon, Oct. 1896.

Costus nemotrichus K.Schum.(1904) 414, f. 47,syn.nov. — Type: Dinklage 954 (holo B destroyed), Cameroon, South Province, Gross-Batanga.

Costus phaeotrichus Loes. (1909) 392, syn. nov. — Type : Zenker 3694 (B destroyed; lecto P, designated here; isolecto BM, E, G, K, L, M, P, S, US, W), Cameroon, South Province , Bipindi (‘Bipindihof’), ‘blühend vom Dezember bis Februar ,1908’;other syntype: Ledermann 945 (B destroyed), Cameroon, South Province , Mfosse, near Nkolebunde, 180 m,

Terrestrial herb 0.2–1 m tall. Leaves several; sheaths brownish red, shiny, more or less turbinate, 0.3–1 cm diam, upper margin irregularly denticulate; ligule chartaceous, truncate, 1–5 mm long; petiole 0–3 mm long; sheaths, ligule and petiole densely to sparsely covered with half-appressed to erect, brown, needle-like hairs to c. 4 mm long to glabrous; lamina often irregularly bullate and 5–10-plicate (Maas 9962), upper side shiny, bright green, lower side reddish to purplish, elliptic to obovate, often slightly asymmetrical, 5.5–18(–22) by 2.5–7(–14) cm, both sides rather densely to sparsely covered with half-appressed to erect, brown, needle-like hairs to c. 4 mm long to glabrous, base cordate, apex acute to acuminate (acumen to c. 10 mm long). Inflorescence few-flowered, (narrowly) ovoid to ellipsoid, 2.5–4 by 1–1.5 cm, terminating a separate leafless shoot 1–9 cm long, or rarely terminating a leafy shoot; bracts, bracteoles, calyx, ovary and capsule glabrous or nearly so. Flowers 2 per bract; bracts brownish red to dark purple, shiny, chartaceous, ovate-triangular, 2–3.5 by 0.7–3 cm, callus brown, 2–4 mm long; appendages absent; bracteole boat-shaped, 22–35 mm long, callus green to yellow, c. 2 mm long; calyx (5–) 10–13 mm long, lobes broadly triangular, 1–2 mm long, callus absent; corolla hyaline, whitish pink, 55–90 mm long, glabrous, tube 15–30 mm long, lobes narrowly elliptic, 30–60 mm long; labellum at the outer side white with dark pink upper half, inner side with white throat, dark pink upper part, or completely dark pink, or rarely completely white, with yellow nectar guide, funnel-shaped to horizontally flattened, broadly obovate when spread out, 35–70 by 40–60 mm, margin undulate and fimbriate; stamen white to pink, 20–45 by 9–12 mm, apex pink to red, anther 5–6 mm long. Capsule broadly obovoid, c. 8 by 7 mm. Seeds 2–3 by 3–4 mm.

Distribution — Central Africa ( Cabinda ( Angola), Cameroon, Congo Brazzaville, Equatorial Guinea, Gabon).

Habitat & Ecology — In non-inundated primary or secondary rainforest, in swamp forest, in dark wet places, on loamy or sandy soil. At elevations of 0–800 m. Flowering and fruiting: all year through.

IUCN Conservation Status — Least Concern.

Notes — Costus tappenbeckianus is characterized by a few-flowered inflorescence terminating a separate leafless shoot with pink (or rarely white) flowers and subsessile leaves with a cordate base. The sheaths, especially those of the separate reproductive leafless shoot, are more or less turbinate with an irregularly denticulate reddish upper margin. The corolla lobes are relatively narrow. Left and right margin of the labellum are not touching each other, thus not forming a complete funnel. A specimen with white flowers is cultivated in Burgers’ Bush, Arnhem, The Netherlands; it was originally collected in Gabon (Maas & Maas 9787).

Costus tappenbeckianus was placed by Schumann (1904: 414) in his new subg. Epicostus together with C. bicolor , C. dendrophilus , C. lanceolatus , C. nemotrichus , C. nudicaulis , C. pauciflorus and C. radicans . According to him these species were all epiphytic (‘saepissime epiphytici’), except for C. tappenbeckianus , had a small and few-flowered inflorescence and nicely coloured, but never yellow, flowers. Costus nudicaulis (now included in C. phyllocephalus ) and the Neotropical species C. lanceolatus were different from the other six species of this sub- genus by an inflorescence terminating a leafy shoot. After an intensive study of the six other species of the subg. Epicostus with an inflorescence terminating a separate leafless shoot, we found that they only differed in minor indument features.

Costus bicolor and C. dendrophilus , of which no material is available (as that has been destroyed) are here considered insufficiently known species (see below)

Paracostus

Paracostus C.D.Specht in Specht & Stevenson (2006) 162. — Type: Tafel 13 of K. Schumann (1892), (the lectotype of Costus englerianus K.Schum. )

Costus L. sect. Paracostus K.Schum. (1899) 343. — Costus subg. Paracostus (K.Schum.) K.Schum. (1904) 381. — Type: Paracostus paradoxus (K.Schum.) C.D.Specht (= Costus paradoxus K.Schum. ).

The genus Paracostus is in Africa represented by only one species: P. englerianus . The second species, P. paradoxus (K.Schum.) C.D.Specht , occurs in Asia (Borneo).