Dichaea andina Alomía & Sambin, 2021

Alomía, Yasmin A., Sambin, Aurelien, Otero, J. Tupac & Stevenson, Pablo R., 2021, A New Species Of Dichaea (Orchidaceae: Zygopetalinae) From The Andes Of Colombia, Phytotaxa 521 (1), pp. 39-47 : 40-42

Dichaea andina Alomía & Sambin , sp. nov.

Type: — COLOMBIA. Valle del Cauca, Western Cordillera , El Cairo, Reserva Comunitaria Cerro El Inglés, 4° 45’ 31.5” N, - 76° 17’ 07.6” W, 2303 m, Andean cloud forest, epiphytic in remnant primary forest, April 09, 2017. Y. A. Alomía 216 (holotype: ANDES; isotypes: CUVC, COL; Figs. 2–5 ) .

Dichaea andina differs from D. lagotis Reichenbach (1876: 112) in the broadly anchoriform lip (vs. sagittate), with the hypochile transversely subrounded (vs. subquadrate) and the epichile transversely narrowly elliptic, briefly apiculate (vs. oblong acute). It differs from D. pendula ( Aublet 1775: 819) Cogniaux (1903: 182) in the caespitose plants (vs. plants not caespitose), the leaves without cross-venation (vs. with cross-venation), and the inflorescence straight, produced under the foliage (vs. geniculated, above the foliage).

Plant epiphytic, caespitose, up to 2 m long. Basal roots 0.6–0.9 cm in diameter, brownish, filiform, flexuous. Caulinar roots ca. 0.4 cm in diameter, greenish, filiform, flexuous, glabrous, protruding from the leaf sheaths. Stems up to 100 × 0.40–0.45 cm and 0.12–0.18 cm thick, covered by conduplicate sheaths, frequently branching, flattened, pendent, arched to erect at the apex. Leaves 2.5–3.7 × 0.5–0.9 cm, green to olive green, distichous along stem, ovate to elliptic-ovate, distinctly apiculate, the margin entire except at the serrulate apex, thin-textured herbaceous, abaxially with a prominent midvein and conspicuous parallel secondary veins. Inflorescence one per node, occurring below the foliage; peduncle 1.4–1.8 × 0.6–1.0 cm, terete, straight, with three tubular overlapping bracts. Floral bract double, the outer bract ca. 6 × 3 mm, widely ovate, acuminate, the inner bract ca. 7 × 0.8 mm, linear, acuminate. Ovary 3 mm long, densely muricate. Flowers in anthesis for 1-2 days, with a sweet fragrance detected between 9:00–15:00 h, sepals and petals pale pink spotted with violet, sepals warty on abaxial surface, lip white with the apical edge outlined in violet as well as two violet spots on the base. Dorsal sepal 9.6 × 3.8 mm, concave, ovate-lanceolate, acute. Lateral sepals 9.2 × 4.1 mm, concave, slightly asymmetrical, elliptic, lanceolate, acute. Petals 7.5 × 3.2 mm, elliptic oblong, acute, margins lightly undulated. Lip subsessile, distally 3-lobed to anchor-shaped, fleshy, glabrous; hypochile ca. 4.5 × 2.7 mm, transversely subrounded forming distinct glabrous shoulders, lateral lobes about 2 mm long, narrowly triangular, filiform, more or less spreading; epichile ca. 4 × 2.3 mm, transversely narrowly elliptic, briefly apiculate. Column 5 × 4 mm, suberect, the base subterete, with two obliquely subquadrate rounded wings, ciliate along the margin; stigma transversely widely elliptic-ovate, strongly depressed; infrastigmatic ligule 1.2 × 0.8 mm, linear, projecting forward, hispid, truncate and bifid at the apex. Anther 1.1 × 1.5 mm, helmet-shaped, 2-celled. Pollinia 4, orbicular, in two superposed pairs of different size; stipe chalice-shaped; viscidium rectangular. Fruit 1.8 × 1.4 cm, ovoid, greenishbrown, densely muricate, exocarp about 2 mm thickness, trichomes broadly triangular, acuminate. Seeds ca. 160 × 60 µm, hyalines and fusiform, pale yellow in immature stages and brownish when ripe.

Additional material studied:— COLOMBIA. Valle del Cauca, Western Cordillera, El Saladito, Bosque de San Antonio , 3°29’45.6”N, - 76°37’29.1”W, 2078 m, Andean cloud forest, epiphytic in remnant primary forest, 11/05/2017, Y. A . Alomía 217 ( ANDES, COL, CUVC) . Huila, East Cordillera, Palestina, Parque Nacional Natural Cueva de los Guácharos , 1°36’26.0”N, - 76°05’45.2”W, 2189 m, Andean cloud forest, epiphytic in primary forest, 21/04/2017, Y. A . Alomía 218 ( ANDES, COL, CUVC), P . Stevenson-2934 ( ANDES). Antioquia, Central Cordillera, San Antonio de Prado , 6°14’42.8”N, - 75°40’36.0”W, 2284 m, Andean cloud forest, epiphytic in remnant primary forest, 10/10/2017, Y. A . Alomía 230 ( ANDES, COL, CUVC) .

Ecology:— Dichaea andina grows in the wet mountainous forests of the Andes mountain range at elevations between 1800 and 2400 m, with a mean temperature of 14.5 °C and a mean relative humidity of 99 %. The plants are found growing on both living trees ( Annonaceae , Arecaceae , Clusiaceae , Cyatheaceae , Lauraceae , Melastomataceae , Myrtaceae , Piperaceae ) and dead trunks, usually in deep shaded areas. Two flowering peaks were recorded twice, one in April–May and another in October–November, although there may be occasional flowering year round. Plants are completely allogamous. Flowers are pollinated by male Euglossa bees which are attracted by volatile floral fragrances primarily composed of 2-(4-methoxyphenyl) ethanol (4-2-hydroxyethyl anisole) and 2-methoxy-phenol (o -Guaiacol) ( Alomía et al. 2018).

Etymology:—The specific epithet is designated for two purposes: first, to honor the Andean forests (Andes mountain range) and second, in recognition of the Universidad de Los Andes, for the academic and institutional support it provided to the first author during her doctoral studies.

Figures

FIGURE 2. Dichaea andina. A. Plant in situ. B. Flower emerging below foliage. C. Flower recently pollinated. D. Muricate fruit. Photographs by Y.A.Alomía.

FIGURE 3. Dichaea andina. A. Habit. B. Inflorescence. C. Ovary, column and lip, lateral view. D. Floral bract and bracteole. E. Column in lateral and ventral views. F. Perianth. G. Fruit, entire and cross section. H. Anther cap and pollinarium in dorsal and ventral views. Photographs by Y.A.Alomía based on the plant that served as type (Y.A. Alomía 216-ANDES).

FIGURE 4. Dichaea andina. A. Habit. B. Inflorescence. C. Ovary, column and lip, lateral view. D. Floral bract and bracteole. E. Column in lateral and ventral views. F. Dissected perianth. G. Fruit entire and cross section. H. Anther cap and pollinarium in dorsal and ventral views. Drawing by Y.A.Alomía based on the plant that served as type (Y.A. Alomía 216-ANDES).