Epidendrum leptopetalum Zambrano & Hágsater, 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 leptopetalum Zambrano & Hágsater , sp. nov. Figs. 11–13

Species haec Epidendrum litense Hágsater & Dodson (1993: pl. 152) similis sed sepalo dorsali linear-lanceolato, acuminato, petalis linear-lanceolatis, acuminatis, 5-nervia, labello trilobato cum callis elliptico-ovatis differt.

Type:— ECUADOR. El Oro: Cantón Atahualpa, sector Daucay , 847 m, 01 July 2017, Zambrano B . 1941 (holotype, QCNE; isotype, QCNE) .

Epiphytic, erect, sympodial, caespitose herb, up to 30 cm tall. Roots 2–3 mm in diameter, from the base of the stems, fleshy, flexuous, white. Stems 21 × 0.4–0.5 cm, cane-like, ancipitose, erect to slightly curved, basal half covered by 4–5 compressed, imbricated, persistent, chartaceous, gray-brown non-foliar sheaths. Leaves 7–8 × 1.0– 1.6 cm, 3–4 distributed along the apical half of the stem, coriaceous, distichous, sessile, oblong-elliptic to lanceolate, obtuse, emarginate at the apex, channeled at the base, light green; sheaths 1.0–3.5 × 0.3–0.4 cm, longitudinally striated, ancipitose, persistent, chartaceous. Inflorescence apical from the mature stem, erect, a raceme with successive flowers; peduncle 10–11 × 1.5–1.6 mm, terete, covered by a chartaceous bract 5–6 × 1.5–1.6 mm, conduplicate, persistent; rachis 1.0– 1.5 mm long, terete; floral bracts 6.5–7.0 mm long, acute, persistent, scarious. Flowers resupinate, the sepals and petals spreading, yellow-green, dorsally purplish, lip cream with the calli and mid-lobe pale yellow, column white suffused with green towards the base, anther white; producing a sweet nocturnal fragrance. Sepals fleshy, margin entire, revolute, 10-veined; dorsal sepal 44–48 × 3.5–4.4 mm, linear-lanceolate, oblique, long-acuminate; lateral sepals 44–48 × 4.8–6.4 mm, obliquely linear-lanceolate, long-acuminate, carinate dorsally. Petals 44–46 × 1.8–2.4 mm, fleshy, linear-lanceolate, long-acuminate, margins entire, revolute, 5-veined, the lateral veins very reduced. Lip 35–39 × 11.0– 12.5 mm, fleshy, 3-lobed, fused to the column, widely cuneate at the base; bicallose, the calli small, laminar, divergent, elliptic-ovate, rounded; lateral lobes 10.0–12.0 × 3.1–4.0 mm, hemi-ovate, slightly obtuse or truncate, inner margin straight, with thickened veins towards the base; mid-lobe 30–32 × 1.8–2.3 mm, longer than the lateral lobes, linear-triangular, long-acuminate, margin entire. Column 10.5–11.0 × 2.7–3 mm, short, slightly arching, terete, lobed apically; clinandrium-hood erose, covering the anther; stigma ventral, short, concave, covered by a viscous substance; rostellum apical, laminar, slit; nectary penetrating almost two-thirds of the ovary, minutely striated longitudinally. Ovary 45–48 × 2.5–2.7 mm, thin, terete, unornamented, thicker near the middle. Anther 0.9 × 0.9 mm, dorsal, obovate, glandular-papillose; pollinarium 0.8 mm long, formed by 4 pollinia, yellow, sub-equal, obovoid, laterally compressed, the inner margin straight, caudicles granulose, longer than the pollinia. Capsule not seen.

Distribution and habitat: — Epidendrum leptopetalum is only known from two populations (Daucay and Monos) in El Oro province ( Fig. 13 ). It grows as an epiphyte on the branches of shrubs of Carapa Aublet (1775: 32) , Ocotea Aublet (1775: 780–781) , and Miconia species at 800–1000 m in elevation.

Phenology: —In cultivation, E. leptopetalum flowered between December and March.

Etymology: —The specific epithet is from the Greek λεπτΟΣ “fine, thin, slender”, and πεταλΟΝ “petal”, in reference to the slender petals.

Additional material examined:— ECUADOR. El Oro: Cantón Atahualpa, sector Daucay , 847 m, 01 July 2017, Zambrano B . s.n. ( QCNE). Cantón Piñas, sector Monos , 1000 m, 19 August 2019, Zambrano B . 2417 (QCNE).

Comments: — Epidendrum leptopetalum belongs to the Nocturnum group, and is distinguished by the light green, oblong-elliptic to lanceolate leaves, yellow-green flowers with lip cream, long-acuminate sepals and petals, and the lip with hemi-ovate, slightly obtuse or truncate lateral lobes. The most similar species is Epidendrum litense from northwestern Ecuador. It differs in the green flowers with the lip white (vs. yellow-green with the lip cream), the smaller dorsal sepal (28–35 mm vs. 44–48 mm long), the 3-veined petals (vs. 5-veined), the lip with triangular-falcate lateral lobes (vs. hemi-ovate), and the shorter column (7.0–8.0 mm vs. 10.5–11.0 mm long). Epidendrum mininocturnum Dodson (1977: 53) from the Chocó region of Colombia and Ecuador, differs in the smaller plants (less than 15 cm vs. up to 30 cm tall), flowers reddish-green to pink with a white lip (vs. yellow-green with a cream lip), the shorter dorsal sepal (27–28 mm vs. 44–48 mm long), the 3-veined petals (vs. 5-veined), and the lip with obliquely semi-ovate lateral lobes (vs. hemi-ovate) ( Sánchez & Hágsater 2010). Epidendrum condornocturnum Hágsater & Tobar (2018a : pl. 1613), restricted to the southeast of Ecuador and possibly Peru, can be distinguished by the elliptic leaves (vs. oblong-elliptic to lanceolate), larger petals (67–87 × 3–4 mm vs. 44 – 46 × 1.8–2.4 mm), larger lip (longer than 5 cm vs. shorter than 3.9 cm), with larger, hemi-elliptic calli (vs. small, elliptic-ovate calli), the narrowly hemi-obovate lateral lobes, half as long as the mid-lobe (vs. hemi-ovate, one third the length of the mid lobe), and the longer column (17–18 mm vs. 10.5–11.0 mm long).

Figures

FIGURE 11. Epidendrum leptopetalum Zambrano & Hágsater. A. Habit. B. Flower, lateral 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 12. Epidendrum leptopetalum Zambrano & Hágsater. A. Habit. B. Flower, lateral view. C. Perianth dissection. D. Ovary and column, lateral view. E. Detail of the column, lateral and ventral view. F. Anther cap and pollinarium. Plate by B.J. Zambrano based on the plant that served as type.

FIGURE 13. Known locality of Epidendrum leptopetalum in southwestern Ecuador. Map by B.J. Zambrano.