Epidendrum amoanum Zambrano & Solano, 2021

Romero, Bosco Javier Zambrano, Hágsater, Eric & Solano, Rodolfo, 2021, Miscellaneous of new species in Epidendrum (Orchidaceae) from southwestern Ecuador, Phytotaxa 511 (2), pp. 111-114 : 111-114

Epidendrum amoanum Zambrano & Solano , sp. nov. Figs. 1–3 .

Species haec Epidendrum amaruënse Hágsater, Collantes & Santiago (2006 : pl. 805), similis sed sepalo dorsali elliptico, petalis oblongis, erosis, labello sub-trilobato differt.

Type:— ECUADOR. Loja: Cantón Loja, vía El Cisne-Ambocas-Portovelo, 2000 m, 02 January 2018, Zambrano B. 2273 (holotype, QCNE; isotype, QCNE [in spirit]) .

Epiphytic, erect, sympodial herb, up to 40 cm tall. Roots 2–3 mm in diameter, scarce, from the base of the stems, fleshy, flexuous, white. Stems 12.0 × 0.2–0.25 cm, cane-like, terete, erect to slightly curved, new stems produced from a middle or sub-apical internode of the previous stem, covered by 5–7 tubular, imbricate, persistent, chartaceous, gray-brown non-foliar sheaths. Leaves 2.5–8.0 × 0.5–0.7 cm, 6–8 distributed along the apical half of the stem, subcoriaceous, distichous, sessile, oblong-lanceolate, obtuse, carinate at the apex, channeled at the base; sheaths 0.4–1.6 × 0.2–0.25 cm, striated longitudinally, tubular, persistent, chartaceous. Inflorescence apical, racemose, arching, shorter than the apical leaf; peduncle 4.0–6.2 × 1.5–1.8 mm, terete, covered by a chartaceous bract 2.0–3.0 × 1.5–1.7 mm, conduplicate, persistent; rachis 10.0–12.5 × 1.4–1.8 mm, terete, slightly pustulate; floral bracts 1.5–4.5 mm long, narrowly triangular, acuminate, persistent, scarious. Flowers 7–8, opening in succession, small, resupinate, the sepals amber-yellow, the petals and lip amber-yellow suffused with brown, column light green, the anther greenish-cream suffused with brown; no fragrance perceived. Sepals fleshy, waxy, margin entire, 3-veined; dorsal sepal 3.4–3.8 × 2.5–2.7 mm, elliptic, rounded, shortly apiculate; lateral sepals 3.8–4.2 × 2.8–3.1 mm, obovate-elliptic, rounded, shortly apiculate, carinate dorsally. Petals 3.5–3.9 × 1.5–1.7 mm, fleshy, oblong, rounded, marginally erose near the apex, 3-veined. Lip 3.8–4.5 × 5.3–5.5 mm, fleshy, fused to the basal half of the column, concave, sub-3-lobed, obliquely reniform-sub-quadrate, deeply cordate at the base, margin erose, truncate at apex, 9-veined, with the lateral veins branched; ecallose, the central disc with 3 parallel, elongate ribs, about half as long as the lip, with 4 additional lateral ribs (two on each side), short and radiating; lateral lobes 3.0–3.3 × 1.4–1.5 mm, transversely elliptic; mid-lobe 0.5–0.8 × 2.3–2.5 mm, much smaller than the lateral lobes, transversely hemielliptic. Column 2.5–3.0 × 2.0– 2.2 mm, short, slightly curved, terete, thick, with a large apical wing on each side, widely rounded; clinandrium-hood short, margin slightly undulate; stigma ventral, concave, covered by a viscous substance; rostellum apical, cleft; nectary short, without penetrating the ovary, unornamented. Ovary 7.0–7.9 × 1.2–1.5 mm, straight, terete, thin, longitudinally sulcate. Anther 0.7 × 1.4 mm, dorsal, trapezoid-reniform, glandular-papillose; pollinarium 0.7 mm long, formed by 4 pollinia, cream-colored, sub-equal, obovate, laterally compressed, caudicles granulose. Capsule not seen.

Distribution and habitat: — Epidendrum amoanum is only known from the Loja province (road to El Cisne-

Portovelo) in southwestern Ecuador ( Fig. 3 ). The plant grows as an epiphyte on the branches of shrubs of Miconia Ruiz

& Pavón (1794: 60) and Euphorbia Linnaeus (1753: 450) species at 2000 m in elevation. Phenology: —In cultivation, E. amoanum flowered between January and August.

Etymology: —The name honors the researchers at the AMO herbarium (Mexico City), in recognition of their outstanding contributions to the knowledge of Neotropical orchids, especially their work on the genus Epidendrum .

Additional material examined: — ECUADOR. Loja: Cantón Loja, vía El Cisne-Ambocas-Portovelo, 2000 m, 02 January 2018, Zambrano B . s.n. (QCNE).

Comments: — Epidendrum amoanum belongs to the Diothonea group, and is recognized by the oblong-lanceolate leaves, amber-yellow flowers, elliptic dorsal sepal, oblong, erose petals, and a sub-3-lobed lip with seven minute keels and truncate apex. The most similar species is the Peruvian E. amaruënse , but it differs in the smaller plants (20 cm vs. 40 cm tall), linear-lanceolate leaves (vs. oblong-lanceolate), non-resupinate, yellow to ochre-green flowers (vs. resupinate, amber-yellow), the ovate dorsal sepal, 5 mm long (vs. elliptic, 3.4–3.8 mm long), the ovate petals (vs. oblong), and an entire lip with 5-keels and 2-lobed apex (vs. sub-3-lobed, with seven minute keels and truncate apex). Epidendrum jativae Dodson (1980 : pl. 85) differs in the non-resupinate flowers, green suffused with burgundy red to purplish brown (vs. resupinate, amber-yellow), elliptic-obovate dorsal sepal (vs. elliptic), petals 6 mm long (vs. 3.5–3.9 mm long), and an entire lip with 3 keels and 4-lobed apex (vs. sub-3-lobed, with 7 minute keels and truncate apex) ( Santiago & Hágsater 2006).

Figures

FIGURE 1. Epidendrum amoanum Zambrano & Solano. A. Habit. B. Flower, 3/4 view. C. Perianth dissection. D. Ovary and column, lateral view. E. Detail of the column, lateral and ventral view. Drawn by B.J. Zambrano based on the plant that served as type.

FIGURE 2. Epidendrum amoanum Zambrano & Solano. A. Habit. B. Apex of the leaf. C. Detail of the peduncle, rachis and floral bracts. D. Flower, 3/4 view. E. Perianth dissection. F. Ovary and column, lateral view. G. Detail of the column, lateral and ventral view. H. Anther cap and pollinarium. Plate by B.J. Zambrano based on the plant that served as type.

FIGURE 3. Known locality for Epidendrum amoanum in southwestern Ecuador. Map by B.J. Zambrano.