Cohniella cayennensis Sambin & Chiron, 2017

Sambin, Aurélien & Chiron, Guy R., 2017, Critical study of the Cohniella (Oncidiinae, Orchidaceae) of French Guiana, Phytotaxa 323 (1), pp. 61-68 : 63-66

Cohniella cayennensis Sambin & Chiron , sp. nov.

Types: FRENCH GUIANA, « Cayenne, route des plages, proche de la plage de Gosselin », leg. Aurélien Sambin, 2016, Cay 01 AS 01, flowering on 17 October 2016 (Holotype: CAY) ; FRENCH GUIANA, « Cayenne, route des plages, proche de la plage de Gosselin », leg. Aurélien Sambin, 2016, flowering on 25 October 2016, FA01 AS 01 (Paratype: HJBG-L 0033 [Herbarium of the Jardin Botanique de Guyane ], flowers in spirit) .

Other materials: P00437152 !; P00437153 !; P 02102929 !.

Haec species Cohniella cebolleta similis est sed plantis pendulis, foliis bevioribus et in sectione basi subquadrangularibus, sepalis latioribus, petalis longioribus, labelli lobis lateralibus distincte angustioribus ascendentibusque, labelli isthmo 2-3-plo latiore, calli parte basali transverse obovata, parte apicali tripartita differt.

Herb epiphytic, caespitose, pendulous, 12–45 cm tall; roots dense, white, glabrous, sinuous, 2 mm diameter; pseudobulbs broadly ovoid, 0.5–1.5 × 0.5–1 cm covered with 3 papery bracts, the largest lanceolate acute, 56 × 16 mm; leaves terete, the biggest subquadrate, canaliculate, thick, leathery and fleshy, dark green most often purple spotted, 17–40 × 0.5–1.2 cm, narrowed from about the middle to the acute, subfalciform apex; inflorescence born at the base of the pseudobulb, slightly bent in the upper half to the apex, greenish-yellow and largely purple spotted, solitary, 1 to 20 flowers (rarely more than 10 flowers opened simultaneously), in raceme, rarely in panicle, 13–70 cm long, with one or two branches up to 5 cm long rather towards the top, often also with an additional short branch beginning on the peduncle, after the main flowering, the branches 1–5 flowered; peduncle up to 47 cm long and 3 mm diameter at the base with 4 to 6 internodes, the largest bract 6 × 3.2 mm, subtriangular, subulate at the apex; flower 2.5 cm diameter, lip yellow, sepals and petals strongly brown spotted; pedicel and ovary 12.2–15 mm long, pedicel whitish, ovary up to 5.5 mm long, subquadrate, greenish; dorsal sepal oblanceolate, apex acute to obtuse, imperceptibly apiculate, slightly concave towards the apex, 9–10 × 6–6.5 mm, lateral sepals similar to the dorsal, 10–11 × 6 mm; petals oblanceolate to obovate, obtuse, sometimes apiculate at the apex, with an irregular, undulating margin, 10–11 × 6 mm; lip trilobed, 16 × 17–18 mm, midlobe transversally oblong, emarginate, 10.3 × 18 mm, upper side entirely yellow, abaxial side with some dull spots in the center, with an apical notch 2 mm long and 2 mm wide, side lobes directed upwards, narrowly ovate to elliptic, subacute to slightly truncate at the apex, 5–6 × 2–2.6 mm, isthmus 1.5–3 × 5–6 mm, disc 5 × 6.5–7 mm with a callus 5.5 × 6.5 mm, yellowish to orange marked with a few scattered and dull spots; callus variable, tripartite, platform transversally obovate, with a strongly irregular, globular apical margin, with 2 small misshapen, sometimes discrete, lateral teeth and a median one elongate to the base of the central keel, proximal teeth absent, distal teeth most often strongly truncated, inconspicuous, or more rarely visible, discrete, rather conical, short and rounded, central keel laterally compressed, elongated up to ¾ of the length of the isthmus, basal part of the callus with inconspicuous, rather conical lateral extensions; column 4–5.1 × 3 mm at the base and 2.5 mm at the apex with two small asymmetrically bilobed wings, wings 2.2–3.5 mm long, distal lobe very small, oval, 1 × 1 mm, proximal lobe oval to rectangular, 2.5 × 1.5 mm; stigmatic cavity rounded, 2 × 2.3 mm; anther 2.6 × 1.5 mm, apical surface microscopically muricated; pollinia, 2, yellowish, 1 × 0.6 mm; fruit ellipsoid, green, purple spotted, 30 × 10 mm. Fig. 1 and 2 .

Phenology: —Flowering from September to the end of November, according to our own observations and the data of the herbarium plates.

Etymology: —the name refers to the city of Cayenne and its surroundings where the type was collected.

Distribution, habitat and conservation status: —This species, hitherto observed only in French Guiana, is known from the coast, often very close to the seashore ( Fig. 3 ) and particularly likes old trees with cracked bark such as Terminalia cf. lucida Hoffmanns. ex Martius (1824: 43) , where the type specimen was collected, Terminalia catappa Linnaeus (1771: 519) or Mangifera indica Linnaeus (1753: 200) . It was observed on Chrysophyllum cf. sanguinolenta ( Pierre 1891: 60) Baehni (1965: 74) at Mana. The site where the type was collected mainly consists of beaches and dunes with herbaceous vegetation, shrubby forests and surrounding xero-mesophile forest.

This orchid of horticultural interest is gradually disappearing under the pressure of intensive collecting, the destruction of its natural habitat due to urbanization and the excessive attendance linked to tourism and seaside activities. We propose the conservation status EN according to the IUCN criteria B2a and D ( IUCN, 2001). Moreover the second author tried to find plants of the Mana population observed in 2004 and did not see one, indicating a possible extinction of this population.

A few specimens are under conservation at the Jardin Botanique de Guyane.

Figures

FIGURE 1. Cohniella cayennensis. A. habit with inflorescence. A1. cross section of the leaf. B. flower. C. dissected flower. D, D1. variations of the callus area. E. column, side view and back view. F. anther and pollinia.A–F: Cay01AS01 (drawing A. Sambin).

FIGURE 2. Cohniella cayennensis. A, B. Plant near Cayenne (ph.A. Sambin). C, D. Plant in Mana (photograph G. Chiron).

FIGURE 3. Map of observations of Cohniella cayennensis specimens. Ɨ: confirmed specimens,?: specimen CAY 1944.