Elleanthus loxensis M.M.Jiménez & Iturralde, 2024

Jiménez, Marco M., Kuethe, J. R., Garzón-Suárez, Henry X., Lapo-González, Nadia, Vélez-Abarca, Leisberth, Salagaje, Luis A. & Iturralde, Gabriel A., 2024, A new white-flowered Elleanthus (Orchidaceae: Sobralieae) from the Andes of southern Ecuador and notes on hummingbird pollination of Elleanthus scopula, Phytotaxa 662 (3), pp. 209-223 : 211-219

Elleanthus loxensis M.M.Jiménez & Iturralde , sp. nov. ( Figures 1–2 , 4–6 )

Type: — ECUADOR. Zamora Chinchipe: Tapichalaca Biological Reserve, Yangana-Valladolid road, 2618 m, (coordinates omitted for conservation reasons; detailed data on the type specimen), flowered in cultivation in Loja, 8 March 2024, M.M. Jiménez 2089 (holotype: HUTPL 15145 !) .

Elleantus loxensis is most similar to E. maculatus but it is distinguished by the stems branching along its length (vs. branching only from the base), the white flowers (vs. purple) with shorter spathulate-lanceolate sepals (7.5–8.3 × 3.5–3.6 mm vs. oblong petals 14–18 × 2–3 mm), the smaller, membranaceous, laciniate lip (9.0–9.9 × 7.3–10.1 mm vs. fleshy, fimbriate lip, 17 × 10 mm), and the base with subreniform calli (vs. obpyriform, globose calli).

Description:— Epiphytic or rarely terrestrial, sympodial, scandent herb, sometimes hanging and arching because of weight, up to 90–100 cm tall including inflorescence. Rhizome short, up to 12 mm long between stems, climbing, thick. Roots 2.0–7.0 mm in diameter, brown, tomentose. Stems 25–75 cm long, 2.0– 3.5 mm in diameter, terete, slightly arcuate, branching from the base and/or along its length; branches around 30 cm long, often branching again, sometimes rooting from the nodes of the base, 2–4 internodes below the leaves, covered by non-foliar sheaths, 22.9–36.8 × 2.0– 3.6 mm, flecked, becoming dry-papyraceous when dry. Leaves 3–8, aggregate at the apex of stems, coriaceous, the upper ones smaller; sheathing petioles 25.0–35.4 × 2.8–4.4 mm, tubular, smooth, green, flecked; blades 4.9–13.4 × 1.0– 2.9 cm, plicate, 5–7 strongly nerved, canaliculate along the veins, lanceolate to narrowly lanceolate or oblong-lanceolate, apex acute, slightly attenuate, medium green on both sides, margins entire, thickened, base sessile, cuneate. Inflorescence 6.0–9.3 × 3.3–5.5 cm, in a conical to cylindric raceme, flowers opening first from near the apex; peduncle 1.7–2.9 cm long, short; basal bract 1 cymbiform, 3.8–5.8 cm long, foliaceous, pale green, flecked, longer than the peduncle, enveloping the base of the rachis for 7–9 mm, base elliptic when spread, apex narrowly lanceolate when spread, obtuse; floral bracts 1.1–4.7 × 0.3–1.2 cm, tubular, pale green, lanceolate to the base, long-acuminate to the apex, flecked, the lower bracts longer than the upper. Flowers 1.5–1.8 × 0.8–1.1 cm, white, lustrous; ovary 5.2–6.8 × 2.1–2.4 mm, green, densely flecked. Sepals concave, mucronate at the apex, slightly flecked to the midvein, margins entire, dorsal sepal 7.3–8.3 × 3.5–3.6 mm, 7-veined, elliptic, acute; lateral sepals 7.9–9.8 × 2.5–3.6 mm, free, 7-veined, keeled dorsally, narrowly ovate, oblique, acute. Petals 7.5–8.9 × 2.5–2.9 mm, 5-veined, spathulate-oblanceolate, centrally channeled, canaliculate dorsally, margin irregularly sinuate in the apical third. Lip 9.0–9.9 × 7.3–10.1 mm, 13-veined, basally saccate, narrowing to the middle; blade cuneate-flabellate, suborbicular when expanded, margin laciniate, emarginate at the apex; calli 2, 2.1 × 3.6 mm, each one subreniform. Column oblong, 4.4–6.0 × 2.6–3.5 mm, complanate, with two short, obtuse, triangular wings to the apex, ventrally concave with winged margins; clinandrium not cucullate, minutely sinuate with two subrectangular and falcate wings to the distal margin; stigma ventral, semicircular, rostellum reniform, rostellar flap lingulate; foot 1.5 mm long. Anther terminal, 2.0 mm wide, rectangular, purple. Pollinarium 8 narrowly obovoid pollinia, 1.6 mm wide, brownish green.

Distribution and ecology:— Elleanthus loxensis is primarily known from the cloud forests facing the inter-Andean valleys of the Loja canton in the province of Loja and the high eastern slope of the Western Ecuadorian Andes of Zamora Chinchipe province, south of Ecuador ( Figures 3 , 4 ). The species grows as an epiphyte on tree trunks covered in mosses or terrestrially in disturbed habitats at elevations between 2200 to 2800 m. Other species of orchids such as E. maculatus , Epidendrum dalessandroi Hágsater & Dodson in Hágsater & Sánchez-Saldaña (2001: 433), Masdevallia deformis Kraenzlin (1921: 428) , Scaphyglottis bicornis ( Lindley 1844: 41) Garay (1967: 255) and Stelis neowerneri Shaw (2014: 78) were found growing sympatrically with E. loxensis . In this area, the local flora is dominated by Centropogon densiflorus Bentham (1844: 138) ( Campanulaceae ), Gynoxys sect. Praegynoxys, sensu Escobari et al. (2023: 85) ( Asteraceae ), Macleania farinosa Mansfeld (1925: 436) , Psammisia fissilis Smith (1950: 372) , Sphyrospermum cordifolium Bentham (1846: 222) and Themistoclesia recondita Smith (1953: 469) ( Ericaceae ).

Occasionally, Elleanthus loxensis was also found growing terrestrially in the El Madrigal Reserve of Podocarpus National Park ( Figure 5 ) together with Gynoxys reinaldi Cuatrecasas (1951: 15) ( Asteraceae ), Hedyosmum sp. ( Chloranthaceae ), Macleania poortmanni Drake (1889: 74) , M. salapa ( Bentham 1844: 141) Hooker ex Hoerold (1909: 269) ( Ericaceae ) and Telipogon ionopogon Reichenbach (1876: 27) ( Orchidaceae ). Its terrestrial form was also seen in the La Argelia-La Palma road which occurs along the crest of the mountain range just southwestern of the Loja basin within the province of Loja.

Etymology:— The specific epithet refers to its occurrence within the region of Loja (formerly known as Loxa in ancient Spanish). Most of its currently known geographic distribution falls within this municipality in southern Ecuador.

Additional specimens examined (paratypes):— ECUADOR. Loja: Cerro Toledo, cerca de Yangana , 2498 m, 24 February 2024, M.M. Jiménez, G.A. Iturralde & H. Garzón-Suárez 2233 ( HUTPL 15146 !) ; oeste de Loja, cerca del Cerro Uritusinga, vía Loja-La Palma , 2790 m, 22 February 2024, M.M. Jiménez, G.A. Iturralde & H. Garzón-Suárez 2196 ( HUTPL 15147 !) ; Reserva Madrigal del Podocarpus , sureste de Loja, 2445 m, 16 Marzo 2024, M.M. Jiménez & N. Espinosa-Ortega 2278 ( HUTPL 15148!) ; Zamora Chinchipe: Area of Estación Científica San Francisco, road Loja-Zamora, ca. 35 km from Loja , near plataforma-open, 2200 m, 22 April 2007, F. Werner, G. Mendieta, K. Diertl & A. Simon 2195 ( QCA 68801 !) ; Eastern side of pass on road from Yangana to Valladolid , 2700 m, 23 Mar 1985, A. Hirtz, C. Luer, J. Luer & W. Flores 2309 ( MO 3743473 !) ; Loja to Zamora along new road from San Francisco to pass , 2500 m, 21 May 1988, A. Hirtz 3855 ( MO 3743472 !) .

Conservation status:— Seven localities of Elleanthus loxensis were identified ( Figure 3 ) across an extended occurrence (EOO) of 520 km 2, with an area of occupancy (AOO) of 30 km 2. Habitat fragmentation due to deforestation for cattle grazing, infrastructure works, and pine plantations are a dominant threat to these natural areas, showing a significant decline in suitable habitats for E. loxensis to grow. The new species has shown a relatively low abundance in situ, and combined with its disappearing habitat the new species should be considered as Vulnerable (VU) in accordance with the IUCN (2024) criteria B2ab (v,iii) and C1. Despite this, fortunately, Elleanthus loxensis is found in the El Madrigal of Podocarpus and Tapichalaca reserves, and its occurrence is expected throughout the nearby Podocarpus National Park, by which the conservation of this species has hope.

Taxonomic discussion:— Elleanthus loxensis is most similar to E. maculatus , both of which show a slender habit (as opposed to robust); inflorescences that are longer than broad; of which the spathes are small and the column without a hood over the anther ( Figures 6–7 ). The new species is distinguished from the latter by the shorter stems branching along its length. In contrast, E. maculatus can grow up to 40 cm tall, and branches only from the base. Additionally, E. loxensis is distinct for having smaller, lanceolate leaves (5–7 veined, acute at the apex, 4.9–13.4 × 1.0– 2.9 cm vs. elliptic leaves 9–11 veined, acuminate at the apex, 15–20 × 1.5–5.5 cm); the shorter inflorescences (6.0– 9.3 cm long vs. 5–12 cm long); the single (vs. up to three), shorter basal bract (3.8–5.8 cm long vs. 8.6 cm long) with lanceolate apex (vs. narrowly triangular to the apex); the shorter floral bracts (11–47 mm long vs. 25–65 mm long); the shorter, white flowers of up to 1.7 cm long (vs. purple flowers up to 2.6 cm long); the shorter and wider petals that are spathulate-lanceolate in outline (7.5–8.3 × 3.5–3.6 mm v s. 1 4–18 × 2–3 mm with oblong outline); the smaller lip (9.0–9.9 × 7.3–10.1 mm vs. 17 × 10 mm) with a membranaceous texture (vs. fleshy), broader width in the middle (vs. narrower), the laciniate margin (vs. fimbriate), and the base with subreniform with separated calli (vs. obpyriform with globose calli); the much shorter and oblong column (4.4–6.0 mm long vs. 10–17 mm long and elongate column); and the pollinia being brownish green (vs. dark purple to blue) ( Garay 1978, Valencia 2020). Other important features observed are the clinandrium with rectangular and falcate wings at the apex (vs. quadrate) and the lingulate rostellar flap (vs. short triangular) ( Figure 7 ).

The new species is also similar to Elleanthus scopula , by having the same branching habit ( Figure 6 ), but differs by the larger, acuminate, 3-veined leaves (4.9–13.4 × 1.0– 2.9 cm vs. smaller, acute, 5–7-veined leaves), 4.0–9.0 × 0.7–1.4 cm); the longer, conical inflorescences (up to 9.3 cm vs. up to 2.5 cm, subglobose); and the white flowers (vs. purple). Additional differences can be seen in the longer floral bracts (up to 47 mm long vs. up to 25 mm long); the spathulate-lanceolate petals (vs. oblong-ligulate) that measure 3.5–3.6 mm wide (vs. 2.0–3.0 mm wide), the membranaceous lip (vs. fleshy) with laciniate margin (vs. finely dentate), and emarginate apex (vs. shortly apiculate); and the shorter floral column (4.4–6.0 mm long vs. 8.0 mm long) ( Garay 1978).

Another species where the stems branch throughout and exhibit white flowers is the Peruvian Elleanthus albiflorus ( Figure 6 ). Elleanthus loxensis differs from E. albiflorus by the larger, acute leaves (4.9–13.4 × 1.0– 2.9 cm vs. acuminate leaves, 3.0–7.5 × 0.8–11.0 cm); the longer, congested inflorescence (up to 9.3 cm long v s. sublax inflorescences of up to 3 cm long), with a longer basal bract, (3.8–5.8 cm long vs. 2.1 cm long); larger floral bracts (11–47 × 3–12 mm vs. 15–18 × 3–4 mm); a longer dorsal sepal that is 7-veined (7.3–8.3 mm long vs. 3-veined and 6.0 mm long); longer lateral sepals, similarly 7-veined (7.9–9.8 mm long vs. 5–6 veined lateral sepals measuring 6.8 mm long); larger petals (7.5–8.9 × 2.5–2.9 mm vs. 6.0 × 1.2 mm); the larger lip that is flat between the basal and apical parts (9.0–9.9 × 7.3–10.1 mm vs. 6.0 × 3.5 mm with a thin transverse thickening between the concave part and the apical part); the subreniform calli (vs. ovoid); and the longer column (4.4–6.0 mm long vs. 4.0 mm long).

In addition to morphological differences, there are also differences in their distribution and habitat. Elleanthus loxensis grows at lower elevations from 2200 to 2800 m and is restricted to the warmer montane forests of southern Ecuador in the provinces of Loja and Zamora Chinchipe, while according to Dodson & Luer (2010) and Valencia (2020), E. maculatus grows at slightly higher altitudes from 2400 up to 3300 m with a wider distribution across the montane and high Andean forests and paramos from Costa Rica to Bolivia. Elleanthus scopula also grows at relatively higher elevations ranging from 2700 to 3500, where it is seen mostly as a terrestrial orchid in high Andean forests and paramos widely distributed from Costa Rica to Bolivia ( Dodson & Luer 2010). This wide distribution, however, may inadvertently incorporate some other (erroneously identified) species, as was seen in some accessions of E. loxensis having been labeled in herbaria as “ E. scopula ”. To the south, the Peruvian endemic E. albiflorus also grows as a terrestrial orchid but is seen in lower premontane forests at elevations not exceeding 2100 m. The distribution is much more limited in lateral extent, where it appears restricted to the department of Pasco, central Peru ( Dudek et al. 2017).

Figures

FIGURE 1. Lankester Composite Dissection Plate (LCDP) of Elleanthus loxensis. A. Habit with a close-up of the internode of a branch (A1) and a leaf in adaxial view (A2). B. Detail of the inflorescence with a flower in frontal view (B1). C. Dissected flower with a closeup of the apical margin (C1) and corpuscules of the lip (C2). D. Lip, column and ovary in lateral views with a longitudinal section of the lip showing the column and corpuscules. E. Column in ventral and ¾ views. F. Pollinarium and anther in adaxial and abaxial views. Elaborated by Nadia Lapo-González based on photographs of the type.

FIGURE 2. Elleanthus loxensis. A. Habit. B. Inflorescence. C. Flower in lateral view. D. Dissected perianth. E. Longitudinal section of the lip showing the column and ovary. F. Column, ventral and ¾ view. G. Anther in abaxial and adaxial view. H. Pollinarium. Drawing by L. Vélez-Abarca from the plant that served as the holotype.

FIGURE 3. Distribution of Elleanthus loxensis in the southern region of Ecuador.

FIGURE 4. Montane cloud forests in southern Ecuador. A. Tapichalaca Reserve. B. El Madrigal of Podocarpus Reserve. C. Slopes of Cerro Toledo near Yangana. Photos: by Marco M. Jiménez (A, B) and Henry Garzón-Suárez (C).

FIGURE 5. Elleanthus loxensis. A, B. In situ photographs in the El Madrigal of Podocarpus Reserve. C, D. Plant in flower in Tapichacala Reserve. E. The first author is photographing the new species in Tapichalaca Reserve. Photos: by Marco M. Jiménez (A, B) and James H. Muchmore Jr. (C–E).

FIGURE 6. Similar species of Elleanthus with ramified stems. A. Elleanthus loxensis. B. Elleanthus maculatus C. Elleanthus albiflorus. D. Elleanthus scopula. Photos: by Rudy Gelis (A), Marco M. Jiménez (B), Henry X. Garzón-Suárez (C) and Luis Yupa (D).

FIGURE 7. Comparison of Elleanthus loxensis based on the holotype and M.M. Jiménez 2196 (left) and E. maculatus based on M.M. Jiménez 2285 and 2291 (right). A. Leaves. B. Floral bracts. C. Flower in lateral view. D. Dissected flower. E. Column with a close-up of the apex and wings of the clinandrium. Photos by Marco M. Jiménez and Henry X. Garzón-Suárez (B1, D1).