Epidendrum scandens Karremans, Chinchilla & Rojas-Alv., 2023

Karremans, Adam P., Rojas-Alvarado, Gustavo & Chinchilla, Isler F., 2023, Epidendrum scandens: an unusual new orchid species endemic to the Cordillera de Talamanca in Costa Rica, Phytotaxa 626 (4), pp. 290-296 : 291-295

Epidendrum scandens Karremans, Chinchilla & Rojas-Alv. , sp. nov. ( Figure 1 ).

Type:— COSTA RICA. Cartago: El Guarco, San Isidro, Paso Macho (Macho Gaff), después del puesto de guardaparques del sector La Esperanza, Chonta , Parque Nacional Tapantí-Macizo de La Muerte , cuenca del Río Macho , camino a Queverí , 09°41’29”N 83°51’58”W, 2850 m, epífitas en árboles al lado del camino, 14 November 2021, A.P. Karremans & M. Contreras Fernández 9012 (holotype: JBL-spirit!; isotype: USJ!) .

Among the members of the Epidendrum rugosum Ames (1923: 74–75) subgroup (Ramosum group), E. scandens is immediately recognized by the large plants with an elongate, scandent, climbing stem, notoriously branching flexuous, becoming liana-like. The overall floral morphology is similar to several species in the group and especially reminiscent of Epidendrum colibri Karremans (2021: 338) . From the latter, the new species is distinguished by the 2–3-flowered inflorescence that is extremely discrete in relation to the stem, the yellowish, non-spreading flowers partially hidden by the large floral bracts and the significantly smaller dimensions of all floral organs. Several species in the group share the apical thickening of the lip, but in E. scandens the apex presents an unusually conspicuously bulbous swelling.

Description: —Epiphytic, large, scandent, climbing herb. The flexuous stems becoming more than 4 m long, forming branched mats that can cover a bush or small tree and drop to the ground. Roots up to 15 cm long, 1 mm in diameter, fleshy, present at the base of the stem to near the apex. Stems 2–3 mm in diameter, branching, climbing, cane-like, terete, conspicuously covered by verrucose sheaths; usually climbing on the surrounding vegetation. Leaves distributed along the stem, deciduous, concentrating close to the apex with age; leaf sheath 9–30 mm long, tubular, verrucose with age, green-yellowish with dark brown warts, becoming scarious with age; blade 1.2–3.3 × 0.3–0.6 cm, thick, coriaceous, oblong to lanceolate, emarginated, with unequally lobes. Inflorescence short, erect, 20–23 mm long from the branches, racemose, subsecund, distichous, congested. Floral bracts 8–13 × 5–6 mm, wider apically, ovate, acute, verrucose, greenish, or pale yellow to scarious with age, covering and exceeding the ovary. Flowers resupinate, 2–3 open simultaneously; the sepals, petals, lip and column, pale yellow. Ovary 6.5–8.3 mm long, terete, trisulcate, thick, fleshy. Sepals free, spreading, ovate to elliptic, acute, apiculate, apically carinate; dorsal sepal 8.5–10.0 × 3.3–3.6 mm; lateral sepals 8.5–10.0 × 3.7–4.0 mm. Petals 8.0–8.8 × 1.5–1.8 mm, free, spreading, linear to narrowly-triangular, acute, inconspicuously apiculate. Lip 7.8–8.3 × 3.4–3.5 mm, trilobed, lacking a basal callus, fleshy, fused to the column, free blade 5.5–6.0 mm long, triangular, acute, margins thickened, elevated, the apex notoriously bulbous-thickened. Column 4.5–5.0 mm long, subclavate, fleshy, slightly bent with respect to the ovary. Anther cap subovoid, thin, 4-celled. Pollinia 4, obovoid, laterally compressed, caudicles soft and granulose. Fruits an ellipsoid capsule, ca. 3.0 × 1.5 cm.

Distribution and habitat: —The species is only known from the Cordillera de Talamanca in Costa Rica, in the very wet to pluvial montane forest, between 2610 and 2850 m in elevation ( Figure 2 ). The plant of E. scandens usually grow up to 4 m in length on shrubs or trees, some of them through their elongated stems may descend to the ground and grow on top of the organic substrate or on rocks, often covering the phorophyte ( Figure 3 ). It also occurs when fragments of the orchid stem fall from the trunk to the ground, and the plant can continue to grow on the substrate. Wonderfully, they can even form a kind of grassland around the trunk of the phorophyte, the latter mostly in plants growing in windy places. In the field, plants have been observed flowering in November and December, and bearing mature fruits in September and October.

Etymology: —The specific epithet comes from the Latin scandens , meaning scandent, in allusion to the highly unusual habit of the plant.

Additional specimens examined: — COSTA RICA. Cartago: El Guarco, San Isidro, Madreselva , Tres de Junio , Carretera Interamericana Sur , km 67, entrada a la finca El Jaular, 9°40’13”N 83°51’56”W, 2610 m, bosque pluvial montano, en bosque secundario de Robles a orillas de la carretera, 25 jun 2021, A.P. Karremans & I. Chinchilla 8808 (USJ!). Puntarenas: Pérez Zeledón, San Pedro, a la orilla del sendero hacia Cerro Ena, entre Quebrada Los Monchos y el páramo de Ena, 9°22’11.79”N 83°27’09.72”W, 2778 m, 27 may 2023, I. Chinchilla et al. 5284 (JBL-spirit!; USJ!) .

Conservation status: — Epidendrum scandens is endemic to Costa Rica, known from three locations on the Cordillera de Talamanca. Its extent of occurrence (EOO) was estimated at 53.523 km 2 with an Area of Occupancy (AOO) of 12 km 2. Fortunately, the localities where this species has been collected are within the montane pluvial forest in the La Amistad International Park and Tapantí-Macizo de La Muerte National Park. Therefore, the species has not been identified as being vulnerable to severe threats. Hence, the species is assessed as Least Concern (LC) following the guidelines and criteria of the IUCN Petitions and Standards Committee (2022).

Taxonomic Discussion: —The new species belongs to the ‘Ramosum group’, ‘Rugosum subgroup’ which feature a branched plant habit, a few-flowered distichous inflorescence, subsecund borne from short secondary stems, verrucose leaf-sheathes and floral bracts often shorter than the ovary, flowers are typically glabrous, concolorous white, green, yellow, or purple, the sepals apically carinate, the petals narrowly lanceolate or linear, the anther cap frequently white with purple markings ( Karremans 2021, Hágsater et al. 2023). Members of this subgroup are generally found growing at mid to high elevations, and although many are restricted in distribution, they tend to be locally abundant. In Middle America, 34 species of the ‘Rugosum subgroup’ have been recorded, all of them are endemic to the region ( Hágsater et al. 2023). Costa Rica registers 30 species, including the novelty proposed here, and is the center of diversity of the group.

Among the members of the ‘Rugosum subgroup’, which normally have short, bushy, erect plants, E. scandens is immediately recognized by the large plants with an elongate, scandent, climbing stem, notoriously branching flexuous, becoming liana-like. The 2–3-flowered inflorescence is extremely discrete in relation to the stem, and the flowers are partially hidden by large floral bracts. The glabrous, pale yellow flowers with ovate to elliptic sepals that are apically carinate, the petals linear to narrowly lanceolate and the triangular lip with the margins thickened are rather typical of the group. Epidendrum colibri Karremans (2021: 338) which has a somewhat scandent habit, has a rather similar flower morphology, but the inflorescences bear 4-5, greenish-cream flowers with radiating purple stripes on the lip (vs. flowers 2–3, concolorous yellow), and the dimensions of all floral organs are significantly smaller (e.g. lip 7.8–8.3 × 3.4–3.5 vs. 4.5 × 2.7 mm).

Figures

FIGURE 1. Lankester Composite Dissection Plate of Epidendrum scandens. A. Habit. B. Inflorescence with flower in 3/4 view. C. Inflorescence with flowers in frontal view. D. Perianth dissected. E. Ovary, column and lip in lateral view and longitudinal section. F. Ovary and column in ventral (left) and lateral (right) views. Photographs by A.P. Karremans, LCDP by G. Rojas-Alvarado based on the type.

FIGURE 2. Distribution of Epidendrum scandens based on the only specimens currently known of this species.

FIGURE 3. Epidendrum scandens in situ. A. Plants growing over the understory plants and soil organic matter (Chinchilla et al. 5284). B. Closeup of the scandent growth of the stems (Karremans & Contreras Fernández 9012). Photographs by I. Chinchilla (A) and A.P. Karremans (B).