Dendrobium moiorum Saputra, Schuit., Wanma & Naive, 2020

Saputra, Reza, Naive, Mark Arcebal K., Wanma, Jimmy Frans & Schuiteman, André, 2020, Dendrobium moiorum (Orchidaceae: Epidendroideae), a new species of Dendrobium section Diplocaulobium from West Papua, Indonesia, Phytotaxa 430 (2), pp. 142-146 : 143

Dendrobium moiorum Saputra, Schuit., Wanma & Naive , sp. nov. Fig. 1 and 2

Type:— INDONESIA. West Papua: Sorong City, Sorong Nature Recreation Park , elev. 100 m, 9 February 2019, Reza 303 (holotype: MAN!, spirit; isotypes: BO!, dried specimen, KRB!, spirit) .

Diagnosis: — Dendrobium moiorum is similar to Dendrobium isthmiferum J.J.Sm. ( Smith, 1935: 41), e.g., in the papillose patch on the mid-lobe between the two undulating keels, but differs in the rectangular, not cuneate, claw of the mid-lobe with strongly undulate margins, the much larger flowers (lip similar in length but sepals almost twice as long as in D. isthmiferum ), larger leaves (13–23.5 cm versus 6.8–10 cm long), and the absence of red or purple markings on the lip, which is unusual in sect. Diplocaulobium .

Epiphytic, sympodial herb. Roots white to brown, up to 10 cm long, ca. 2mm in diameter, stiff, unbranched. Rhizome very short, creeping, sometimes branched, covered by deciduous, dull yellow to brown scales. Pseudobulb clustered, erect, bottle-shaped, 15.0–35.5 × 1.6 (at the base) to 0.3 (near the apex) cm, green to olive green, widened at the base, tapering towards the apex, sulcate, stem-like, covered by deciduous dull yellow-brown bracts at the base, unifoliate. Leaves erect, elliptic to lanceolate, rarely oblanceolate, 13.0–23.5 × 3.3–4.0 cm, coriaceous, glabrous, adaxially dark green, shiny, abaxially bright green, base cuneate to attenuate, margin entire, apex emarginate or unequally bilobed. Inflorescence arising from the apex of the pseudobulb, 1-flowered, singly or sometimes in pairs, nodding; peduncle 2.0– 2.3 cm long, terete, glabrous; spathe formed by 3 scale-leaves, ovate to triangular, ca. 3.5 × 0.7 cm wide (1.4 cm wide when flattened), dull yellow to brown, papery, glabrous, margin entire, apex acute. Pedicel-with-ovary clavate, slightly curved, up to 9 cm long, terete, ovary not distinct, glabrous, pale green. Flowers up to 8 cm across (petal and sepal in natural position), up to 9 cm across when expanded, ephemeral. Dorsal sepal erect, ovate-triangular in basal part, narrowly linear in apical part, 6.1–6.4 × 0.4–0.5 cm, tapering, glabrous, white in the lower half, pale yellow towards apex, margin entire, apex slightly twisted, caudate, cucullate. Lateral sepals spreading, slight obliquely triangular in basal part, narrowly linear in apical part, falcate, 5.4–6.4 × 0.5–0.6 cm, tapering, glabrous, white in the lower half, pale yellow towards apex, margin entire, apex slightly twisted, caudate, cucullate. Petals narrowly ovate in basal part, linear in apical part, slightly falcate, 5.1–5.4 × 0.25–0.26 cm, tapering, glabrous, white in the lower half, pale yellow towards apex, margin entire, apex slightly twisted, caudate, cucullate. Labellum porrect from a suberect base, reclinate, pandurate, ca. 13.2–13.5 × 5–7 mm when flattened, 3-lobed, cuneate at base, with two parallel keels extending from the base of the lip to about halfway the mid-lobe, the keels straight between the lateral lobes and undulate on the mid-lobe; side lobes erect, rounded, sinuate, 2.0– 3.3 mm long, glabrous, creamy white to yellowish white; mid-lobe spatulate, 4.5–5.5 mm long, clawed, claw almost rectangular, with two parallel undulate keels extending from the base to just below the blade, disc minutely papillose between the undulate keels, bright yellow, margin strongly undulate, apex rounded, margin sinuate, creamy white to pale yellow; mentum 4.5 mm long, obtuse. Column ca. 5 mm long, obtuse; anther pale yellow, rectangular-rounded, cucullate, in front minutely fimbriate and with a short, subulate projection on either side; pollinia 4, narrowly ovoid, 1.5–1.6 × 0.4–0.6 mm, dull yellow-brown, arranged in two pairs. Fruit not seen.

Distribution:—Indonesian New Guinea, Bird’s Head Peninsula. Only known from the type locality.

Habitat and Ecology: —Lowland rainforest at ca. 100 m a.s.l. in shaded and semi-open places without direct sunlight.

Phenology:—Observed flowering in February and July-September.

Etymology: —The specific epithet moiorum refers to a local tribe in Sorong, West Papua, the Moi, who protect the Sorong Nature Recreation Park forest and first brought this species to our attention.

Conservation status: —During field surveys in one year, we only found 11 individuals in two populations. The distribution of this species as presently known is very narrow, with an estimated population size of fewer than 1000 individuals. Despite Sorong Nature Recreation Park being a protected forest (conservation forest), the habitat of this species is prone to the effects of anthropogenic activities such as site disturbance, habitat fragmentation, and village expansion. According to the Red List criteria of the IUCN (2019), we assess this species as Vulnerable (VU C2a(i); D2).

Figures

FIGURE 1. Dendrobium moiorum A. Habit. B. Flower. C. Petal. D. Dorsal sepal. E. Lateral sepal. F–I. Lip. J. Pollinia. K. Anther. L. Pedicel with ovary. Scale bar, single line=1 cm, double lines=5 cm, triple lines=5 mm. Drawn from the type by Reza Saputra.

FIGURE 2. Dendrobium moiorum.A. Habit. B. Detail of pseudobulbs. C. Inflorescence. D. Flower. E. Detail of labellum (Front view & Profile view), scale bar: 2 mm. F. Dorsal sepal, scale bar: 2 cm. G. Lateral sepal, scale bar: 2 cm. H. Petal, scale bar: 2 cm. I. Pedicel with ovary, scale bar: 5 cm. J. Pollinia, scale bar: 1 mm. K.Anther. Photos by Reza Saputra.