Epidendrum machinense M. F. Escal. & Rinc.- Gonzalez, sp. nov.
Creators: name: Rincón-González, Milton
name: Escalante, María Fernanda
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Liliopsida
Asparagales
Orchidaceae
Epidendrum
Epidendrum machinense

description: Epidendrum machinense M.F.Escal. & Rinc.–González sp. nov. (Figs. 2, 3)
Type: — COLOMBIA. Ibagué: Departamento del Tolima. Vereda el Guaico, Cráter Volcán Cerro Machín, 2363 m, 7 de enero de 2019. María F. Escalante & Milton Rincón 170 (holotype: TOLI).
Diagnosis: Epidendrum machinense is similar to Epidendrum coryophorum (Kunth) Rchb. f. but is distinguished by the plants that are 32–37 cm tall including the inflorescence (vs plants 15–30 cm tall), having more flowers 50–80- flowered (vs 10–34-flowered), the sepals and petals that are yellow tinged purple-brown, with apices yellow, and the column and lip white tinged wine-red (vs purple flowers, apices often white), the petals oblong, 1.4 mm wide, 3-veined (vs petals linear, 0.5–0.6 mm wide, 1-veined), and the lip 3–lobed, bicallose (vs linear, ecallose).
Epiphytic, sympodial, caespitose plant, 32–37 cm tall including the inflorescence. Roots from the base of each stem, thin, fleshy. Stem 10–15 x 0.5–0.6 cm, cane–like, produced from the lower nodes of the anterior stem, erect, straight, cylindrical, laterally flattened towards the apex. Leaf 1, at the apex of the stem; leaf sheaths 8–11 mm long, tubular, striated, smooth to finely rugose; blade 13–15 × 1.0 cm, elliptic–lanceolate, margin entire, apex obtuse. Spathaceous bracts 9–10 × 0.83 cm, 1 or rarely 2, oblong, acute. Inflorescence 22–28 cm long, apical, racemose, cylindrical, generally dense many-flowered; peduncle 9–10 cm, covered almost entirely by the spathe; rachis straight, generally arching when mature. Flowers 50–80, simultaneous, lip uppermost in the basal-most flowers (non-resupinate), but due to the arching inflorescence, the lip lower-most in the flowers most distal (resupinate), sepals and petals yellow tinged purple-brown, apices yellow, column and lip white tinged or spotted wine-red; without fragrance. Floral bracts 5 mm long, much shorter than the ovary, triangular, acute. Ovary 8 mm long, finely striated, curved, purple. Dorsal sepal 7.0 × 2.5 mm, spreading to reflexed, ovate–elliptic, apex obtuse, 3–veined, margin entire; lateral sepals 7.4 × 3.7 mm, parallel to the column, elliptical, slightly falcate, concave, apex obtuse, 3–veined, margin entire. Petals 6.5 × 1.4 mm, spreading, oblong, base cuneate, apex rounded, 3–veined, margin entire. Lip 5.0 × 3.5 mm, united to the column, 3-lobed, margin entire; bicallose, calli rounded, laterally flattened, erect, divergent, prominent; lateral lobes 1.0 × 0.6 mm, sub-ovate, membranous, twisted, broadly hamate in natural position, laterally extended; mid-lobe 4.2 × 1.5 mm, narrowly triangular, fleshy, forming a wide arch, apex rhombic or bifid, inflexed. Column 3.7 × 2 mm, straight, short, thick, wide at apex, white irregularly marked with wine-red. Clinandrium–hood short, funnel-shaped, margin erose. Anther widely reniform, 4–celled, yellow. Pollinia 4, obovoid, laterally compressed; caudicles soft and granulose; viscidium wide, viscous. Rostellum apical, slit. Lobes lateral of stigma prominent, 1/2 the length of the stigmatic cavity. Nectary wide and elongated, penetrates about half of the pedicellate ovary, not ornamented. Capsule ellipsoid, carinate.
Distribution and Ecology: Epidendrum machinense is only known from a small area within the crater of the Cerro Machín volcano in the municipality of Ibague, department of Tolima. This volcano is categorized by the Servicio Geológico Colombiano (SGC) as active in resting state, therefore, the vegetation found there would be at high risk of disappearing due to a volcanic event. The species was found in the humid montane forest (bh–M) (Holdridge, 1967) between 2300 and 2600 m of elevation, and it is found growing in the middle and top of trees of the genus Inga (Fabaceae, Mimosoideae) and trees of Tibouchina lepidota (Bonpl.) Baill (1877: 74) (Melastomataceae).
Phenology: Flowering was observed in the month of January.
Conservation: Data deficient (DD).
Etymology: In reference to the Cerro Machín volcano where the type specimen was collected. With this epithet, the authors want to give visibility to this place, so that the relics of humid montane forest that still exist are subject to conservation.
Discussion: In our survey of the subgroup Stenoglossum, we find that all species have flowers with the lip uppermost on the base of rachis, however, due to a drooping of the rachis, the distal flowers have a lower-most, leaving the largest amount of flowers in a resupinate position. Authors such as Fischer et al. (2007) have shown that in the genus Bulbophyllum (Orchidaceae) 10 types of resupination occur in 210 species, and that not all are directly related to the twist of the pedicel. We believe that more studies on the resupination of Epidendrum groups are needed to determine if this feature is phylogenetically significant.
Epidendrum machinense belongs to the Mancum group (Fig. 4), characterized by the sympodial habit, stems of few leaves, a racemose, ancipitose, elongate inflorescence with 1–2 bracts with parallel sides; and the Stenoglossum subgroup having flowers that become resupinate (lip lowermost) by the drooping of the rachis, a short column, an entire or 3-lobed lip, tiny hamate lateral lobes and a filiform linear mid-lobe with a rhomboid sagittal apex. The species can be recognized by the tall size of the plants, 32–37 cm tall including the inflorescence, the inflorescence 22–28 cm long with 50–80 simultaneous flowers with yellow corolla stained purple-brown with yellow apices and a white lip and a column with numerous wine-red spots, a dorsal sepal shorter than the lateral sepals, the petals extended laterally in relation to the column, 3-veined, and the 3-lobed lip, lateral lobes broadly hamate in natural position, triangularlinear mid-lobe, apex inflexed, rhombic or bifid apex, and bicallose. Epidendrum coryophorum is distinguished by the smaller plants, 15–30 cm tall including the inflorescence, the inflorescence 8–23 cm long with 10–34 simultaneous flowers, the purple flowers often with white apices, the narrow petals, parallel to the column, 1–veined, and by the linear lip without calli (Figure 4 B). Epidendrum hamatum differs from this species in the size of the inflorescence, between 8–23 cm long, the 25–28 simultaneous greenish yellow flowers with multiple purple dots, the spatulate petals, and the lip with hamate lateral lobes, short and thin (vs medium and wide), and the mid-lobe linear–filiform with rhombic apex (Figure 4 C). Probably, the greatest diversity of this subgroup occurs in Colombia, since the three described species are found in the country; two are endemic, whilst Epidendrum coryophorum is distributed from the central Andes in Colombia to northern Ecuador.
description: Published as part of Rincón-González, Milton & Escalante, María Fernanda, 2020, Epidendrum machinense (Orchidaceae: Laeliinae), a new species from Colombia, pp. 33-40 in Phytotaxa 435 (1) on pages 35-38, DOI: 10.11646/phytotaxa.435.1.4, http://zenodo.org/record/13875318