Gastrodia bambu Metusala, 2017

Metusala, Destario & Supriatna, Jatna, 2017, Gastrodia bambu (Orchidaceae: Epidendroideae), A New Species from Java, Indonesia, Phytotaxa 317 (3), pp. 211-218 : 212-217

Gastrodia bambu Metusala , sp. nov. (Figs. 1,2,3)

Type:— INDONESIA. Java: Yogyakarta Province, Sleman Regency, Mount Merapi, Turgo. c. 800 m, 20 March 2016, RIO 8997 (holotype: BO!).

Diagnosis: — Gastrodia bambu is close to Gastrodia abscondita J.J.Sm. , but differs in having larger dark brown flowers (17 – 20 mm × 14 – 16 mm), a longer perianth tube (≥ 17 mm), ovate petals, a longer oblong-lanceolate lip (≥ 10 mm), different shape keels on the lip, and a different shape column.

Terrestrial, holomycotrophic. Rhizome tuberous, succulent, cylindrical, 3.5 – 9 cm long × 5 – 9 mm in diameter, dark brown, covered with numerous scales. Roots few, slender, usually extending from base or middle part of the rhizome. Inflorescence erect; peduncle greenish brown to pale brown, 3 – 13 cm tall × 0.3 – 0.5 cm in diameter, glabrous, 2 – 5 nodes, a tubular sheath on each internodes; sheaths triangular to ovate, light brown to reddish brown, 6 – 9 mm long × 6 – 11 mm wide, thin, membranous, apex acute; 1 – 8 flowers, spreading, several flowers open simultaneously; flower bract narrowly triangular, 5 – 7 mm long x 2.5 – 3 mm wide, acute. Pedicel and ovary slender, light brown or cream to reddish brown, 15 – 20 mm long. Flower resupinate, tubular, campanulate, 17 – 20 mm long × 14 – 16 mm wide at front, not opening widely, smelling of rotten fish; slightly glossy, sepals and petals dark brown to blackish brown; lip orange at base, whitish-brown in middle, tinged orange at apex, basal callus white; column greenish brown, apical half suffused white-orange; anther-cap white to yellowish-white. Sepals and petals connate, forming a 5-lobed tube, 17 – 20 mm long, outer surface slightly verrucose, inner surface wrinkled/rugose. Sepals subsimilar, fleshy; lateral sepals connate to each other for c. 50 – 55 % of their length and connate to dorsal sepal for c. 65 – 75 % of their length; lateral sepals free part obliquely triangular, 6 – 10 mm long × 9 – 11 mm wide, margins slightly undulate, apex obtuse to acute; dorsal sepal free part broadly triangular, 6 – 10 mm long × 9 – 12 mm wide, margins slightly undulate, apex rounded to slightly retuse. Petals adnate to sepals, forming a floral tube, slightly fleshy, free part ovate, base slightly contracted, 5 – 6 mm long × 3 – 4 mm wide, margins irregular and slightly undulate, apex obtuse. Lip adnate to columnfoot apex, enclosed within perianth tube, fleshy, oblong-lanceolate, 10 – 12 mm long × 3.5 – 4 mm wide; basal area with 2 verrucose ovoid calli; disc convex, pubescent except for glabrous apex; with three longitudinal keels, the low median keel extending from between basal calli to about halfway along the lip where it elevates gradually become an erect thin plate-like keel that terminates near the lip apex, the outer two keels are lower and less distinct, usually extending along the apical half of the lip; lip lateral margins irregular and slightly ascending; lip apex slightly canaliculate, obtuse to acute. Column elongate, slightly arcuate, canaliculate, narrowly winged along its length, 10 – 12 mm long × 2 – 2.5 mm wide at base, broadening to c. 3 mm wide near the middle then narrowing gradually to c. 2 mm near the truncate apex; stelidia indistinct, very small, tooth-like, acute; stigma borne on a raised projection at column base, semi-circle to ovate; anther-cap subrectangular, 1 – 1.2 mm × 1 mm; pollinia 2. Capsule erect, cylindrical, 1.8 – 3 cm long × 0.5 – 0.7 cm in diam., brown; pedicel elongates up to 26 cm long during fruit maturation.

Distribution and phenology:—The distribution of Gastrodia bambu appears to be restricted to Java. Populations have been discovered in Yogyakarta Province on Mount Merapi at c. 800 m., and more recently (28 January 2017) in West Java Province, Sukabumi, Bodogol, Mount Gede Pangrango, at c. 800 m. All these populations were found very close to old bamboo clumps, growing in wet soil containing partly-decomposed bamboo leaf litter, in the very deep shade cast by the bamboo plant’s canopy. Flowering recorded from mid February to mid March (Mount Merapi) and mid January to mid February (Mount Gede Pangrango).

Etymology:—The specific epithet “bambu ” refers to the Indonesian name for bamboo, the dominant plant associated with this new species.

Discussion:— Gastrodia bambu is morphologically close to Gastrodia abscondita , but differs in having larger (17 – 20 mm × 14 – 16 mm) dark brown flowers, a longer perianth tube (17 – 20 mm), petals with an ovate free part (5 – 6 mm long × 3 – 4 mm wide), an oblong-lanceolate lip that is longer (10 – 12 mm) and has three longitudinal keels, a longer column (10 – 12 mm) with narrow column wings along its length, and very small tooth-like stelidia. By contrast, Gastrodia abscondita has smaller (13 mm × 11 mm) pale gray flowers, a shorter perianth tube (13 mm), petals with a 3.7 mm × 1.7 mm oblong free part, a shorter (6 mm) sub-sagittate lip with an ovate-triangular blade and 5 longitudinal ridges, a shorter column (5.5 mm) with wider column wings only in the apical half, and large triangular stelidia. Morphological comparison between G. bambu , G. abscondita , and G. crispa are shown in Table 1.

Conservation:—It seems that the Gastrodia bambu requires very specific ecological conditions and is very sensitive to environmental changes. Previous studies have shown that Gastrodia species have specific mycorrhizal associations throughout their life cycle, making them very vulnerable to habitat disturbance ( Martos et al. 2009; Selosse et al. 2010; Martos et al. 2015). The extent of occurrence of this species has been estimated at less than 5000 km 2. The population in Gede Pangrango Mountain is inside the National Park and therefore protected, but in Merapi Mountain the species is known from few locations, all outside the National Park boundary, where the quality of habitat is rapidly declining due to clear-cutting of bamboo clumps for logs. It is also threatened by the hot clouds released intermittently by Mount Merapi, a highly active volcano. Its population size is estimated fewer than 1000 individuals. Therefore, we consider this species to be a category of “Endangered” according to the IUCN Red List Categories and Criteria ( IUCN, 2016).