Dendrobium dedeksantosoi Metusala 2021, sp. nov.
Creators: name: Metusala, Destario
name: Saputra, Reza
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Liliopsida
Asparagales
Orchidaceae
Dendrobium
Dendrobium dedeksantosoi

description: Dendrobium dedeksantosoi Metusala, sp. nov. (Figs. 1, 2, 3, 4A)   
Type:— INDONESIA. Maluku: North Maluku, Halmahera. 50–350 m, RIO 9260 (holotype BO!)  
 Diagnosis:— Dendrobium dedeksantosoi is morphologically closest to D. busuangense, but differs in having shorter (2.4–2.6 cm long) oblanceolate petals (vs. 3.5–3.85 cm long narrowly oblong petals); broadly ovate to broadly subrhomboid labellum (vs. oblong elliptic labellum); transversely oblong to broadly obcordate mid-lobe (much wider than its length) with emarginate apex (vs. oblong mid-lobe (much longer than its width) with obtuse to acuminate apex); and the length ratio between column: column-foot is about 1:1 (vs. 1:2).   
Epiphytic herb. Roots numerous from the rhizome and base of stem, velamen dirty white when old. Stem erect to sub-erect, up to 140 cm high, up to 2 cm in diam., more or less cylindrical, stiff, mature stem usually swollen in the lower third, leafy above the swollen section, leafy part of stem green, leafless stem reddish brown. Sheath encircling stem tightly, greenish or yellowish green when young and becomes grayish brown when old, long-persisting. Leaves articulated to a sheathing base, deciduous, alternate-distichous, suberect to 55°, fleshy, coriaceous, rather stiff, oblong elliptic, 6.5–15.0 cm long × 3.3–5.5 cm wide, apex obtuse or shortly unequally bilobed, waxy adaxially, green. Inflorescence one to several, arising from upper part of stem, erect; peduncle cylindrical, 8.0–12.0 cm long, 0.4–0.5 cm in diam. at base, light green; rachis 10–30 cm long with 7–28 flowers; floral bract oblong ovate to narrowly triangular, 4.0 5.0 mm × long 2.5–3.0 mm wide obtuse to acute, usually slightly smaller at the upper flowers, cream or greenish. Pedicel-with-ovary cylindrical, slightly wider toward apex, 3.0– 4.3 cm long, light green to light greenish-cream, green more pronounced at ovary. Flower rather thick textured, 3.2–3.9 cm high × 3.0– 4.2 cm wide, sepals spreading to decurved, petals erect to sub-erect, sepals and petals greenish-yellow to yellowish-green, labellum red-purplish with greenish or yellowish margins at the mid-lobe, ridges cream-white as the base color, suffused with purplish at basal 3/4 and white at apical third; column pale green or greenish-yellow and sometimes brownish at base, column-foot suffused purple. Dorsal sepal oblong-triangular to oblong-ovate, 1.9–2.3 cm long × 0.8–0.9 cm wide, undulate, obtuse or sometimes shortly acuminate, recurved backward and slightly twisted in natural shape. Petals obliquely oblanceolate, 2.4–2.6 cm long × 0.2–0.3 cm wide at base, gradually widened to 0.6–0.75 cm towards apex (widest near apex), obtuse to subacute, margins rather undulate, half to one full twist in natural shape. Lateral sepals obliquely and narrowly triangular to oblong-triangular, 2.2–2.4 cm long from the middle x 1.1–1.3 cm at the widest part, margins undulate, obtuse to subacute, or sometimes shortly acuminate. Mentum conical, 1.2–1.4 cm long, slightly curved near apex, apex obtuse, greenish near apex. Labellum porrect, trilobed, broadly ovate or broadly subrhomboid or sometimes broadly subrectangular in outline (without claw), when flattened 2.3–2.6 cm long (without lip’s claw) × 2.2–2.6 cm wide at side-lobes; side lobes obliquely broadly obreniform to broadly rhomboid, 2.0– 2.2 cm long, front margins irregularly crisped or undulate, free part at front 3.0–4.0 mm long, forming a triangular to slightly falcate lobe, apex obtuse; mid-lobe transversely oblong to broadly obcordate, 0.6–0.75 cm long × 0.9–1.1 cm wide, margins undulate, apex emarginate; callus on lip disc 3-ridged, straight (not undulate) throughout the whole length, mid-ridge immediately raised at apex to form an oblong-triangular obtuse flap-like callus (c. 3 mm high), lateral ridges lie sideways from the base of the lip disc extending towards the basal third to half way of the mid-lobe, usually there is a low longitudinal nerve located directly on each side of central prominent ridges. Column porrect, oblong, 1.1–1.2 cm long; column-foot 1.1–1.2 cm long; stigma oblong-elliptic, c. 3.0 x 1.5 mm; stelidia truncate or sometimes with obscurely denticulate at apex; anther-cap cucullate, more or less rectangular in outline when viewed from the front, greenish or yellowish, 2.5 × 2.5–3.0 mm; pollinia comma-shaped, 4 in 2 pairs, c. 2 mm high, yellow. Capsules not seen.  
 Distribution and phenology:—the distribution of Dendrobium dedeksantosoi appears to be restricted to Halmahera, Maluku Islands, Indonesia. Growing as epiphyte in semi-open forest at altitudes of 50– 350 m. Flowering recorded in late March to late April, early June, mid August, mid September to mid October (cultivation, Java Island 200–850 m elev.) and early November (in natural habitat).   
 Etymology:—named after Dedek Setia Santoso, an Indonesian orchid grower as well as philanthropists who shows a great concern in the orchid conservation, especially through breeding and cultivation activities of the Dendrobium section Spatulata.   
 Cultivation:— Dendrobium dedeksantosoi is quite easy to cultivate at altitudes of 50–850 m elev. This species grows best using charcoal as the medium, with a top dressing of sphagnum-moss or coconut husk to prevent the roots from drying-out. Recommended light intensity is 70–85 percent with good air circulation and regular watering.   
 Discussion:—This new species belonging to section Spatulata is morphologically most similar to D. busuangense (Figure 5A–C), D. stockelbuschii (Figure 5D), and D. burkeanum (Figure 6A). Morphological comparison among several closely related species is shown in Table 1.   
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 Dendrobium dedeksantosoi differs from D. busuangense in having shorter oblanceolate petals (≤ 2.7 cm long), broadly ovate to broadly subrhomboid labellum, transversely oblong to broadly obcordate mid-lobe (much wider than its length) with emarginate apex, and the length ratio between column: column-foot is about 1:1. Meanwhile, D. busuangense has longer narrowly oblong petals (> 3.5 cm long), oblong elliptic labellum, oblong mid-lobe with obtuse to acuminate apex (much longer than its width), and the length ratio between column: column-foot is about 1:2.   
 Dendrobium dedeksantosoi differs from D. stockelbuschii in having front free part of the lip side-lobes which are forming a triangular to slightly falcate obtuse lobe, callus of 3-ridges where only the mid that raised to form a high flap-like callus, and column length (1.1–1.2 cm) that is more or less as long as the column-foot (1.1–1.2 cm). On the other hand, D. stockelbuschii has lip side-lobes without front free part, callus of 3-ridges where all raised immediately at apex to form triangular to oblong-triangular obtuse flap-like callus (mid is taller than the laterals), and column length (0.8–0.9 cm) that is much shorter than the column-foot (1.5–1.6 cm).   
 Dendrobium dedeksantosoi differs from D. burkeanum in having oblong triangular to oblong ovate dorsal sepal, broadly ovate to broadly subrhomboid labellum, 3 rather low and straight ridges where the mid immediately raised at apex to form a large oblong-triangular obtuse flap-like callus, and column length (1.1–1.2 cm) that is more or less as long as the column-foot (1.1–1.2 cm). In contrast, Dendrobium burkeanum has oblong elliptic dorsal sepal, oblong obovate labellum, 5-lamellate keels where the mid raised gradually towards apex to form an undulate-sigmoid lamellae where it terminates at 3 mm high, and column length (0.7–0.8 cm) that is much shorter than the column-foot (1.1–1.2 cm).   
 Conservation status:—Quite many plants of Dendrobium dedeksantosoi have been collected from its natural habitat in the last 7 years, mainly brought to Java as ornamental plants. Meanwhile, in-depth assessment of all known individuals in their natural habitat has not yet been done; therefore any accurate data to support determination of their status may not be available in the near future. A field survey and assessment need to be conducted immediately in order to determine their conservation status based on the IUCN Red List Categories and Criteria.
description: Published as part of Metusala, Destario & Saputra, Reza, 2021, A New Species of Dendrobium Section Spatulata From Maluku, Indonesia, pp. 269-278 in Phytotaxa 528 (5) on pages 270-276, DOI: 10.11646/phytotaxa.528.5.1, http://zenodo.org/record/5800470