Dendrobium ormerodii Handoyo, Naive & J.Champ., 2021

Naive, Mark Arcebal K., Handoyo, Frankie & Champion, Jeffrey, 2021, Dendrobium ormerodii (Orchidaceae, Dendrobieae), a new Dendrobium species from Central Kalimantan, Indonesia, Phytotaxa 524 (3), pp. 205-209 : 206-208

Dendrobium ormerodii Handoyo, Naive & J.Champ. sp. nov. ( Fig. 1–2 )

This species is closely similar to Dendrobium fulminicaule J.J.Sm. (1917: 51) but differs in having shorter stem, narrower leaf, dorsal sepal with acute apex, labellum without sidelobes or without the broadening at the base, labellum apex obtuse-truncate, shorter pedicel and ovary, and shorter column.

Type:— INDONESIA. Borneo , Central Kalimantan, cultivated plant, March 2021, JKC 023 (holotype, THBB) .

Description: Epiphytic herbs. Roots 1.0– 1.4 mm in diameter, verrucose, greenish white, becoming brown when old. Stem clustered, erect to semi pendant, up to 30 cm long, basal 5 cm cylindrical, the remaining length flattened, subclavate, distinctly grooved, brown to greenish brown; internodes 8–13, (12–17) 22–27 mm long, (1.2–1.8) 7–8 mm in diam., covered with persistent sheaths. Leaves distichous, 6.5–8.0 cm long by 1.0– 1.3 cm wide (largest leaf), linear lanceolate, dark green suffused with purple, chartaceous, glabrous on both sides, margin entire, apex acute; sheath longer than the internode, striate, green with purplish red streak when young, grey to brownish green when old. Inflorescences shortly racemose, mostly borne from upper leafless stem, 1–2 per node bearing 2–5 flowers, 1.2–1.5 cm long, peduncle and bracts persist after flowering, peduncle suberect to pendant, terete, glabrous, brownish green; floral bracts 1–2 mm long, triangular, greenish brown to vermillion, glabrous on both sides, margin entire, apex attenuate. Flower lasting 4–6 days, 2.2–2.4 cm long, 1.8–2.0 cm across, not opening widely, amber, sepals richly stippled with purple outside, petals with a narrow purple midline or midnerve, mentum suffused with purple, lip with purple red blotches except the creamy white apex, column and column foot with purple marks or markings. Pedicel with ovary 8–12 mm long, cylindrical, sulcate, reddish green with purple streak, curved. Dorsal sepal 5-nerved, porrect, 10.0– 10.2 mm long by 3.9–4.1 mm wide, ovate, glabrous on both sides, margin entire, apex acute. Lateral sepals 6-nerved, spreading, inner margin 10.0– 11.4 mm long, outer margin 17.0– 17.6 mm long, 5.0– 5.5 mm wide, obliquely triangular, falcate, margin entire, apex acute, cucullate. Mentum narrowly conical, 9.0– 10.2 mm long, 4.2–4.4 mm across at the widest point, 2.6–2.8 mm wide at the apex, somewhat incurve, apex truncate to obtuse. Petals 5-nerved, spreading, 12.0– 12.4 mm long by 3.0– 3.4 mm wide, oblong to narrowly obovate, apex acute, curved upwards. Lip 2.0– 2.2 cm long, rhombic from a short claw, erect, concave, shortly clawed or unguiculate; claw ligulate-oblong, fleshy, basal 1–2 mm adnate to the column foot, free part 5–6 mm long, in total ca. 6–7 mm long by 1.7–2.0 mm wide; blade not trilobed, broadly ovate to elliptic (when flattened), 14–15 mm long by 8–9 mm wide at the centre, 4.0– 4.5 mm wide at the apex (when flattened), glabrous on both sides, shortly ventricose to excavate-concave below, suberect, apex recurved, margin minutely erose to entire, undulate, obtuse-truncate; disc thick, with 3–5 low longitudinal callus ridges from the centre to the apex of blade. Column porrect, stout, 2.0– 2.5 mm long, 2.0– 2.2 mm in diam. at base; column foot 9.4–10.0 mm long, slightly incurved; stelidia triangular, 0.5 mm long, whitish with purple markings, obtusely acute; stigma oblong, 0.8–1.0 mm in diam.; rostellum absent; pollinia 4, in two pairs, each pair can be divided into two parts, c. 0.8 mm long; anther cap 1.7 mm long, 1.3 mm across, ovate, white, cucullate. Capsule not seen.

Distribution and habitat:— The species is currently only known to come from Batapah, Central Kalimantan, Indonesia where it grows as epiphyte in lowland forest with shaded to slightly lit localities at elevations of 100– 400 m. In cultivation, the species thrives at an elevation of 1,100 m a.s.l. with a shaded environment.

Phenology:— In cultivation, this species flowers in the months of February, March and April.

Etymology:— The specific epithet ‘ ormerodii ’ was coined in honour of Paul Abel Ormerod (1969-), for his great contribution in the taxonomy of family Orchidaceae in Asia and Australia.

Proposed conservation status:— This species is an endemic orchid of Kalimantan, but only known from a cultivated individual. Nothing is known about its occurrence in wild, number of locations, population size and population decline (if present). However, it is obvious that the species is being collected for trade, which is a threat for its existence. Owing to the inadequate information we treat this species as ‘Data Deficient’ (DD) following IUCN (2019).

Taxonomic Notes:— This new species, Dendrobium ormerodii , was found to resemble D. fulminicaule . However, D. ormerodii significantly differs from D. fulminicaule in having shorter stem (~ 30 cm long vs. ~ 53 cm long), narrower leaf (~ 1.5 cm wide vs. ~ 2.7 cm wide), dorsal sepal with acute apex (vs. obtuse), labellum without side lobes or without broadening at the base (vs. inconspicuously trilobed), labellum apex obtuse-truncate (vs. rotund-bilobed), shorter pedicel and ovary (~ 12 mm long vs. ~ 18.5 mm long), and shorter column (~ 2.5 mm long vs. 3.5 mm long).

Figures

FIGURE 1. Dendrobium ormerodii Handoyo, Naive & J.Champ. sp. nov. A. Habit B. Flower C. Dorsal sepal D. Lateral sepals E. Petals F. Anther G. Column and column foot H. Labellum (flattened) I. Side view of Pedicel and ovary, column and column foot; Labellum. Drawn by: Probo Guritno.

FIGURE 2. Dendrobium ormerodii Handoyo, Naive & J.Champ. sp. nov. A. Habit B. Inflorescence appearing from leafless stem C. Flowers D. Detail of flowers E. Detail of Labellum F. Side view of Pedicel and ovary, column and column foot; front view of column foot G. Dorsal sepal H. Lateral sepals I. Petals J. Anther. Photos by: J. Champion (A) and F. Handoyo (B–J).