Kylicanthe rohrii (Rchb.f.) Descourvières & Farminhão 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 : 115-116

Kylicanthe rohrii (Rchb.f.) Descourvières & Farminhão , comb. nov. ( Fig. 2F )

Basionym: Angraecum rohrii Reichenbach (1881: 117) .

Type :— ETHIOPIA. Shewa: sine loc., s. d., Roth s.n. (holotype: K! [K000306246]; isotypes: S! [S07-6835], W! [W-Rchb.0011369, scan]) .

Homotypic synonyms:— Angorchis rohrii (Rchb.f.) Kuntze (1891: 651) . Diaphananthe rohrii (Rchb.f.) Summerhayes (1960: 140) .

Epiphytic herbs. Roots numerous, distributed basally, unbranched, greyish, 2–4 mm in diameter. Stem with a few leaves in a fan, up to 55 mm long, 3–10 mm in diameter, unbranched, pendent to erect, internodes 2–5 mm. Leaves distichous, less than 10, narrowly elliptic to elliptic, tessellated, margins entire, apex subequally bilobate without a clear notch, lobes obtuse to rounded, 63–123 × 10–17 mm. Inflorescences usually 1 to 3, semi–pendent, emerging at the base of the stem, with up to 15 flowers, 30–220 mm long, floral internodes about 3–15 mm, rachis terete; bracts amplexicaul, 2–6 mm long. Flowers resupinate, greenish to greenish–yellow, 9.5–12.5 mm in diameter; dorsal sepal elliptic, sometimes obovate, apex obtuse to subacute, margins entire, 4.7–5.6 × 2.3–2.5 mm; lateral sepals obliquely elliptic sublinear to linear, slightly keeled dorsally, apex obtuse to subacute, margins entire, 1–5-veined, 4.6–5.5 × 1.7– 2.0 mm; angle between dorsal and lateral sepals about 120° but then with a torsion that places it at 180 ° to the dorsal sepal; petals elliptic linear, apex obtuse to subacute, margins entire, 4.3–5.3 × 1.5 mm; lip broadly ovate, margins entire, spreading, with a callus, apex generally subacute, sometimes with a little notch, 3,5,7-veined, 4–4.6– × 3.2–4.0 mm; lip callus, a prominent raised tooth in the mouth of the spur; spur more or less curved, pendent, roughly circular in cross section, mouth slightly spreading, apex rounded and obscurely flattened, proximal part of the spur approximately parallel to the ovary, 10.0– 13.5 mm long; ovary and pedicel 7.5–8.0 × 0.8–1.5 mm. Column 2.0–3.0 × 4.0– 4.2 mm; anther cavity approximately perpendicular to the axis of the column; stigmatic cavity cup-shaped, margins winged, 3 veins; rostellum triangular, bifid, about 1 mm long; pollinia 2, spherical; stipes 2, spatulate, separate along their length, with a bulging outer margin, fringed, 1.0– 1.6 mm long, connected to a single calceiform viscidium. Fruits ventricose, pedicellate.

Distribution: —Confined to East Africa, where it is known from the Ethiopian Highlands, Mount Elgon (Eastern Uganda and Kenya), the Aberdare Range ( Kenya) and the Ngorongoro Crater ( Tanzania), up to 3,000 m ( Fig. 3 ).

Habitat and ecology: —Epiphytic in primary and secondary forests.

Phenology: —Flowering January–October.

Conservation status: —The IUCN Red List category is vulnerable [VU]. The extent of occurrence (EOO) of K. rohrii is estimated to be over 218,068 km 2 (far exceeding the 20,000 km 2 upper limit for vulnerable category under the criterion B1), whereas its minimal area of occupancy (AOO) is estimated to be 40 km 2, which falls within the limits for endangered category under the criterion B2. Kylicanthe rohrii is an East African endemic and has been collected in four protected areas. This species is known from ten specimens representing nine subpopulations. These nine subpopulations represent a total of eight “locations” (sensu IUCN, 2012), exceeding the upper limit for endangered category, but falling within the limits for vulnerable category. We project that the on-going loss of its habitat will induce a decline in the number of subpopulations and mature individuals in the next ten years as well as a decline of its EOO and AOO. Kylicanthe rohrii is therefore assigned a preliminary status of VU B2ab(i,ii,iii,iv,v).

Etymology: —The species epithet commemorates Johannes Rudolf Roth (1815–1858), the collector of the type material, and it is actually based on a misspelling of the collector’s name. Dr. Roth, not ‘Rohr’ as indicated by Reichenbach (1881), was the naturalist appointed to the 1841–1843 expedition to the Shewa region in Ethiopia led by Major William Cornwallis Harris ( Harris 1844).

Notes: —After being “rediscovered” by Summerhayes (1960), this species has been regarded as conspecific to K. quintasii but can be distinguished from the later by its rounded leaf apex with subequal lobes and slenderer flower pedicels (see K. quintasii for further discriminating characters). Kylicanthe rohrii is the only species of the genus recorded for East Africa. Fieldwork in further localities of the Kenyan and Tanzanian highlands, and possibly in the Imatong Mountains of South Sudan, should likely expand the range of this species.

Additional specimens examined: — ETHIOPIA. Oromia: 9 miles east of Shashamane on Goba road, montane forest, 2,050 m, 3 June 1974 (flowered in cultivation in Addis Ababa, 18 June 1974), Ash 2522 (K) ; Entoto Hills above Addis Ababa, 1 July 2011, Edwards in Demissew 6978 (K) . KENYA. Rift valley: Kitale District , March 1938, Cunningham-van Sommeren 36 (K) ; NE Elgon, May 1960, Tweedie 2015 (K); Nakuru – Thomson’s Falls, 10 km behind Dundori , 20 March 1978, Pfennig Pf. 1351 (K) ; Central: Aberdare Mts, Kinangop , 2,680 –2,700 m, April 1938, Chandler 2386 (BR, K) ; S. Aberdare Mts. , 28 January 1952, Archer 8 (K) ;.. UGANDA. Northern: Mt. Elgon Bulambuli, 14 July 1934, Snowden 921 (BM, K) ; Mt. Elgon, B?– Sasa Hut , 10 October 1962, C. L. O. R. 25 (K) . TANZANIA. Arusha: Ngorongoro Crater S rim, road to Karatu 5 km before junction to Lemala , 2,350 m, 23 September 1977, Raynal 19229 (P, K [drawing]) .

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.