Kylicanthe bueae (Schltr.) Farminhão, Stévart & Droissart 2018

Descourvières, Pascal, Farminhão, João N. M., Dubuisson, Vincent Droissart Jean-Yves, Simo-Droissart, Murielle & Stévart, Tariq, 2018, A new genus of angraecoid orchids (Orchidaceae: Angraecinae) with highly distinctive pollinaria morphology, including three new species from tropical West and Central Africa, Phytotaxa 373 (2), pp. 99-120 : 106-108

Kylicanthe bueae (Schltr.) Farminhão, Stévart & Droissart , comb. nov. ( Figs. 2D , 5 )

Basionym:— Angraecum bueae Schltr. Type:— CAMEROON. Southwest: Buea, c. 1,000 m, July 1905, Deistel s.n. (holotype: B†, [drawing K000107149!]). Buea, 21 June 1947, Gregory 153 (neotype here designated: K! [K000107148]).

Homotypic synonym:— Diaphananthe bueae (Schltr.) Schlechter (1918: 96) .

Epiphytic herbs. Roots basal on the stem, unbranched, greyish, 3–4 mm in diameter. Stem with a few leaves in a fan, up to 25 mm long, up to 10 mm in diameter. Leaves less than 10, oblong, elliptic sublinear to linear, sometimes slightly falcate, margins entire, apex unequally bilobed with a short notch of 0.1–2.0 mm, lobes acute, 45–105 × 9–13 mm. Inflorescences usually 1 to 3, pendent, emerging at the base of the stem, 4–16-flowered, 80–170 mm long, floral internodes about 5–14 mm, rachis terete; bracts amplexicaul, about 2–3 mm long. Flowers resupinate, white or whitish, greenish, yellowish, 10–15 mm in diameter; dorsal sepal elliptic, apex obtuse to subacute, margins entire, 3–5-veined, 5.0–8.6 x 2.4–4.1 mm; lateral sepals obliquely elliptic linear, slightly keeled dorsally, apex obtuse to acute, margins entire, 3–5-veined, 5.0–8.1 × 2.0– 3.7 mm; angle between dorsal and lateral sepals about 120°; petals elliptic linear, apex obtuse to subacute, margins entire, triveined, 4.0–8.0 × 1.2–2.2 mm; lip ovate, entire, margins entire, lateral margins not or only slightly deflexed, 5–9-veined, with a callus, apex acute, 4.0–8.7 × 3.0– 4.4 mm; lip callus like a small tooth; spur tubular, pendent, strongly geniculate, distal part more or less dilated and dorso-ventrally flattened, apex rounded or bilobulate, angle formed by the ovary and the proximal part of the spur 20–45°, 10–12 mm long; ovary and pedicel 6.5–8.5 × 1.0– 1.2 mm. Column 2.5–5.0 × 2.5–3.5 mm; anther cavity in ventral position, facing the lip; stigmatic cavity cup-shaped, margins large and winged, 3 veins generally visible; rostellum triangular and bifid, about 1 mm long; pollinia 2, spherical; 1 stipe, obcordate, with fringed margins, 1.0– 1.5 mm long, connected to a single, calceiform viscidium.

Distribution: —Mount Cameroon and Cameroonian highlands, in the area of the Oku Massif, c. 1,000 –2,600 m ( Fig. 3 ).

Habitat and ecology: —Epiphytic in forests and savannah woodlands.

Phenology: —Flowering March–July.

Conservation status: —The IUCN Red List category is endangered [EN]. The extent of occurrence (EOO) of K. bueae is estimated to be over 5,748 km 2 (which falls within the limits for vulnerable category under the criterion B1) whereas its minimal area of occupancy (AOO) is estimated to be 32 km 2, which falls within the limits for endangered category under the criterion B2. Kylicanthe bueae is endemic to Cameroon and has been collected outside the Mont Cameroon National Park and in the Oku Massif. It is thus known from two subpopulations occurring in several unprotected forests subjected to high level of degradation. This species is known from nine specimens representing seven subpopulations. These seven subpopulations represent a total of six locations (sensu IUCN 2017), above the upper limit for endangered category. We project that the on-going loss of its habitat will induce a continuous decline in the number of subpopulations and mature individuals in the next ten years as well as an important decline of its EOO and AOO. Kylicanthe bueae is therefore assigned a IUCN status of VU B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v).

Notes: —The holotype of Angraecum bueae (Deistel s.n.) was almost certainly lost during the bombing raids of Berlin on the night of 1-2 March 1943. A tracing of the type drawn by Summerhayes survives at Kew, but no plant material remains from the original collection. The neotype, Gregory 153 (K!), examined and drawn by Summerhayes, was chosen because it is from the type locality. Kylicanthe bueae is the largest-flowered species in the genus, and the overall appearance of its flowers bears some resemblance to that of Aerangis pallidiflora Perrier (1938: 36) and especially to Aerangis seegeri Senghas (1983: 23) from Madagascar, the latter also possessing a short geniculate spur with a somewhat inflated tip. Further fieldwork in Bioko, Cameroon and Nigeria (Chappal Waddi) would likely expand its range.

Additional specimens examined: — CAMEROON. Northwest : Bali Ngemba, s.d., Chiron 01235 (LY [scan]) ; près Kichong (30 Km SSE de Nkambé), 2,200 m, 13 July 1967, Letouzey 8889 (P) ; Tadu 11 km WNW of Kumbo, 26 June 1973, Mbenkum 354 (P!) ; near Verkovi Village , lower slopes of Mt. Oku, 2,200 –2,600 m, April 1986, Thomas & McLeod 6051 (MO, K [scan], YA) ; Belo , Mont Oku, autour du lac, 2,300 m, 6°11’8.00”N 10°25’19.89”E’, 19 May 2014, Yaoundé shadehouse series 5098 (BRLU!) ; ibid. loc., 4 March 2015, Yaoundé shadehouse series 5958 (BRLU, YA) ; Boyo , Mbi Crater, 2,040 m, N06°05 ′ 49 ″, E10°21 ′ 12 ″, 3 May 2002, Pollard 1154 (K, YA) .

Figures

FIGURE 2. Overview of Kylicanthe diversity. A. Kylicanthe arcuata, plants growing as twig epiphytes in Mt. Etindé (Cameroon) and detail of the flowers. B. Kylicanthe perezverae, seed capsules of a plant grown at the Nimba shadehouse (Guinea). C. Kylicanthe liae, habit and detail of a flower showing a prominent orange viscidium, in cultivation at Huye orchid garden of the University of Koblenz- Landau guest house (Rwanda). D. Kylicanthe bueae, habit of a plant grown at Yaoundé shadehouse (Cameroon) and detail of a flower. E. Kylicanthe quintasii, detail of inflorescence of a plant from São Tomé Island. F. Kylicanthe rohrii, detail of inflorescence of a plant from Tanzania. G. Kylicanthe cornuata, detail of flowers of a plant grown at Yaoundé shadehouse (Cameroon). Photographs by: A., D. and G. Vincent Droissart; B. Ehoarn Bidault; C. Eberhard Fischer; E. Tariq Stévart; F. W. Bachmann, facilitated by the World Orchid Iconography of the Swiss Orchid Foundation at the Herbarium Jany Renz (Botanical Institute, University of Basel, Switzerland).

FIGURE 3. Distribution of the seven species of Kylicanthe in tropical Africa.

FIGURE 5. Kylicanthe bueae. A. Habit. B. Inflorescence. C. Flower in lateral view. D. Flower in frontal view. E. Dorsal sepal. F. Lateral sepal. G. Petals. H. Lip in lateral view. I. Lip in frontal view. J. Floral pedicel, ovary and column. K. Column in lateral view. L. Column in frontal view. M. Pollinaria in dorsal view. N. Pollinaria in lateral view. Drawn by Hans de Vries after Yaoundé shadehouse series 5098 & 5958.