Dendrochilum ignisiflorum M.N.Tamayo & R.Bustam., 2020

Tamayo, Maverick N., Pranada, Mc Andrew K. & Bustamante, Rene Alfred Anton, 2020, Dendrochilum ignisiflorum (Coelogyninae, Arethuseae, Orchidaceae), a new species from Luzon Island, Philippines, Phytotaxa 455 (4), pp. 240-244 : 241-242

Dendrochilum ignisiflorum M.N.Tamayo & R.Bustam. , sp. nov. ( Figs. 1 & 2 )

subg. Platyclinis

Type:— PHILIPPINES. Luzon, Cordillera Administrative Region, Benguet Province, Municipality of Bokod , Mt. Komkompol ( UARBRR) mossy forest, at ca. 2300 m elevation, 08 March 2020, M . N . Tamayo 0196 (Holotype: PNH!; Isotypes: NLUH!; PUH!) .

Diagnosis:— Dendrochilum ignisiflorum is most similar to D. vanoverberghii by having petiolate leaves, channelled petioles, labellum of the same size, and the erect to suberect incurved column. However, the new species is distinct by the sub-globose or broadly ellipsoid pseudobulb (vs. fusiform to ellipsoid), 3 distinct leaf veins (vs. 1 distinct), barely spreading flowers (vs. spreading), 1-veined sepal and petal (vs. 3-veined), lanceolate and revolute dorsal sepal (vs. oblong and spreading), yellow to bright orange labellum (vs. red), absence of callus (vs. present), broadly lunate sidelobes (vs. broadly and falcately oblong) and a 3-pronged midlobe (vs. transversely rectangular).

Description:— Small, glabrous, epiphytic herbs. Roots emerging from the rhizome (and pseudobulbs), thin, unbranched. Pseudobulbs clustered on a short rhizome, occasionally brownish or reddish near tips, sub-globose or broadly ellipsoid, 5–8 mm × 4–5 mm, 1-leaved, initially covered with 1 tubular, acute to acuminate, glabrous cataphylls which soon disintegrate into persistent fibers. Leaf conduplicate, petiolate; petiole distinctly channelled, 5–6 mm long; blade dorsiventrally complanate, pale green both the adaxial and abaxial, sometimes leathery, linear lanceolate, acute or obtuse, 18–35 mm × 1.5–2.5 mm, crenulate with 3 distinct veins (6 indistinct veins), each of the outer ones ca. 0.5 mm from margin. Inflorescence exceeding the subtending leaf at anthesis; synanthous, racemose; peduncle reddish to brownish, erect, slender, terete, 5–6.5 cm long, devoid of pubescence; rachis erect or semi-arching with distichously alternating flowers, dense, 12–18 flowered with internodes of 2–3 mm, terete, faintly quadrangular, furrowed, 25–35 mm long, glabrous, basally with 2 non-floriferous bracts. Floral bracts light brown, persistent, glumaceous, broadly ovate when spread, acute to acuminate, 1.8–2.8 mm × 1–2 mm, hyaline on margin, entire, scarious, many-veined. Flowers barely spreading, yellow to bright orange. Sepals and petals glabrous, 1-veined; dorsal sepal lanceolate, acuminate, revolute, 2–3 mm × 1–2 mm, entire; lateral sepals lanceolate, acuminate, 2.5–3 mm × 1.5–2 mm, entire, barely spreading; petals lanceolate, acuminate, 2–3 mm × 1–1.5 mm, barely spreading. Labellum porrect, minute, sessile, 3-lobed, devoid of disc ornamentations such as calli and ridges, yellow to bright orange, dark orange near the middle; side-lobes broadly lunate with round apices, mid-lobe three-pronged, not projecting beyond the side lobes, lateral prongs auriculate and rounded, the middle one acuminate, 0.7–1 mm × ca. 1 mm, indistinct vein. Column suberect to erect, short, incurved, terete, ca. 1 mm long, hooded at apex, column foot absent, attached directly to base of labellum. Anther oblong to lanceolate in upper view, lobed posteriorly, broadly oblong in front, furrowed in the middle. Pollinia not observed. Ovary (including pedicel) terete, slightly curved, ca. 1 mm, glabrous. Capsule not observed.

Etymology:— The epithet ‘ignisiflorum’ is a combination of the Latin words ignis (fire); flores (flowers). Hence, the name directly translates to ‘fire flowers’ as depicted by its barely spreading yellow to bright orange flowers.

Distribution and Habitat:— Exposed ridges and mossy forest summit within the bounds of Mt. Komkompol (UARBRR), Municipality of Bokod, Benguet ca. 2300 m elevation.

Phenology:— Flowering from March to April. Fruiting from April to May.

Proposed Conservation Status:— Flowering individuals were present only on exposed ridges especially on the mountain summit of the type locality at ca. 2300 m elevation. The plant is no longer present at 500 meters away from the summit. The occurrence of the species is thus perceived rare within the locality and threats like land conversion and tourism activities may pose a risk to the population. It is thus proposed to be Vulnerable ( VU) B2 ( IUCN Standards and Petitions Committee, 2019) .

Figures

FIGURE 1. Dendrochilum ignisiflorum M.N.Tamayo & R.Bustam., sp. nov. A. Habitat on the mossy forest summit of Mt. Komkompol, Bokod, Benguet (UARBRR); B. Leaf abaxial surface; C. Plant habit in situ; D. Closer view of the flower including the labellum and column; E. Pseudobulbs; F. Anterior view of the inflorescence; G. Lateral view of the inflorescence. Photos: A, C, by M.N. Tamayo; B, D-G by M.A.K. Pranada. (All from M.N. Tamayo 0196).

FIGURE 2. Dendrochilum ignisiflorum M.N.Tamayo & R.Bustam., sp. nov. Flowers (A. Anterior view; A’. Anterior view (spread); A”. Lateral view); B. Flattened labellum; C. Lateral sepal; C’. Petal; C”. Dorsal sepal; D. Lateral view of column; E. Leaf; F. Plant habit; G. Bract. (All from M.N. Tamayo 0196). Illustration by M.N. Tamayo.