Taxonomic studies on Zingiberaceae of Myanmar II: Curcuma stolonifera (Subgenus Ecomatae), a new species from the northwestern region

Taxonomic studies on Zingiberaceae of Myanmar II: Curcuma stolonifera (Subgenus Ecomatae), a new species from the northwestern region

Brittonia, XX(X), 2020, pp. 1–5
© 2020, by The New York Botanical Garden Press, Bronx, NY 10458-5126 U.S.A.  

NOBUYUKI TANAKA1, KATE ARMSTRONG2, MU MU AUNG3, AND AKIYO NAIKI4

1  Department of Botany, National Museum of Nature and Science, Amakubo 4-1-1, Tsukuba, Ibaraki, 305- 0005, Japan; e-mail: nobuyuki_tanaka@kahaku.go.jp

2  New York Botanical Garden, 2900 Southern Blvd, Bronx, NY 10458, USA

3  Forest Research Institute, Forest Department, Ministry of Environmental Conservation and Forestry, Yezin, Nay Pyi Taw, Myanmar

4  Iriomote Station, Tropical Biosphere Research Center, University of the Ryukyus, Taketomi-cho, Yaeyama-gun, Okinawa, Japan

Abstract. In the course of taxonomic studies on Zingiberaceae in Myanmar, a new species of Curcuma assignable to subgenus Ecomatae was discovered in Htamanthi Wildlife Sanctuary, Sagaing Region, northwestern Myanmar. It is described and illustrated here as Curcuma stolonifera. This new species differs from other species in subgenus Ecomatae Škorničk. & Šída f. in having a combination of the following characters; long creeping rhizomes, an oblong- lanceolate lamina with reddish midrib, a small number of green bracts, a central inflorescence, pale whitish yellow flowers, and a short slightly L-shaped anther with a curved spur.

Keywords: Burma, ginger, Htamanthi, new taxon, Sagaing Region, Upper Chindwin.

Continental Southeast Asia is an important bio- diversity hotspot for the family Zingiberaceae (Tanaka & Aung, 2019), and the flora of Myan- mar is one of the region’s most poorly document- ed. To improve the knowledge of Zingiberaceae in Myanmar, expeditions to the northwestern and southeastern regions, which are the most under- collected areas of the country, were carried out. Thus far, our recent fieldwork has revealed many new or newly recorded species of the Zingiberaceae (Aung et al., 2015a, b, 2017; Mood et al., 2016; Tanaka & Aung, 2017; Tanaka et al., 2018; Tanaka & Aung, 2019). Recently, Curcuma kayahensis Nob. Tanaka & Aung was described (Tanaka & Aung, 2019) from southeastern Myanmar as the first in a series of papers.

The genus Curcuma is the second largest genus in the Zingiberaceae and comprises 120 species that occur throughout tropical and subtropical Asia from India to southern China, Southeast Asia, Papua New Guinea and northern Australia (Wu & Larsen, 2000; Záveská et al., 2012). Twenty-two species of subgenus Ecomatae were recognized (Tanaka & Aung, 2019), and quite recently two more species, C. tongii Y.H. Tan & L.X. Zhang (Zhang et al., 2019) and C. putii Maknoi & Jenjitt. (Maknoi et al., 2019) were described from China and Thailand, respectively. Thus far, a total of 25 species of Curcuma subge- nus Ecomatae are known.

In the course of studying specimens collected from Htamanthi Wildlife Sanctuary, Sagaing Region, another unidentified species of Curcuma L. was discovered. It is assignable to a member of subgenus Ecomatae, which is characterized by epigynous glands, anther spurs and lack of a conspicuous coma of sterile bracts (Leong- Škorničková et al., 2015).

The newly collected species has unique characters, which distinguish it from any other species thus far described. This species is characterized by having long creeping rhizomes, a lanceolate lamina with a reddish midrib, a small number of green bracts, a central inflorescence, pale whitish yellow flowers, and a short, slightly L-shaped anther with a curved spur. It is confirmed as a hitherto-undescribed taxon because it cannot be matched with any known taxon. Consequently, we describe it here as Curcuma stolonifera Nob. Tanaka, K. Armstrong & M.M. Aung in the taxonomic treatment below. Curcuma stolonifera is the third species of subgenus Ecomatae recorded from Myanmar.

The type locality in the eastern foothills of Nagaland is influenced by an Indian floristic element (Tanaka et al., 2007). The taxonomic position of the new species within subgenus Ecomatae is uncertain because no morphologically similar species occur in South Asia or Indochi- na. Further studies in neighboring regions may reveal related taxa.

Materials and methods

Photographs, herbarium specimens and alcohol- preserved specimens were collected in the field. Specimens were examined morphologically and the description was made based on living material, herbarium specimens and spirit collections. The terminology used in the description follows Beentje (2016). Types are deposited in NY, RAF and TNS. The preliminary conservation assessments follow the categories and criteria of the IUCN (2012) and the guidelines of IUCN Standards and Petitions Committee (2019).

Taxonomic treatment

Curcuma stolonifera Nob. Tanaka, K. Armstrong & M. M. Aung, sp. nov. Type: Myanmar, Sagaing Region: near the Nam Ei Zu bridge, Nam Ei Zu, Hkamti Township, Htamanthi Wildlife Sanctuary, 150 m elevation, 25°31′ 12.57”N, 95°24′6.42′′E, 14 Sep 2016, Nobuyuki Tanaka, Akiyo Naiki, Mu Mu Aung MY925 (holotype: TNS [TNS01283611]; isotypes: NY, RAF). (Figs.1, 2.)

Diagnosis: This species differs from other species in sub-genus Ecomatae by a combination of the following characters: long creeping rhizomes, oblong-lanceolate lamina with a red- dish midrib, a central and short inflorescence, pale whitish yellow flowers, and a short, slightly L-shaped anther with a curved spur.

Rhizomatous perennial herb to 40 cm tall. Rhizome slender, creeping, 8–9 cm long, 5–7 mm wide, creamy white externally, yellowish internally, tubers not observed, aromatic. Leafy shoots with 4–6 leaves at anthesis, pseudostems 20–30 cm long, green, sometimes reddish at the base, composed of sheathing bracts and leaf

sheaths; sheathing bracts 2–4, light green, gla- brous; leaf sheaths light green, margin hairy; ligule up to 2 mm long, bilobed, lobes acuminate at apex, membranous, whitish, pubescent; petiole 10–13 cm long, canaliculate, whitish green, gla- brous; leaf blade slightly unequal, usually green with a dark red band running along the midrib for almost the entire length of the lamina, central section of midrib more deeply colored, some- times green throughout without red band, ob- long-lanceolate, 30–37 cm long, 4–5.5 cm wide, plicate, adaxially bright green, glabrous, abaxially dull green, glabrous on both sides; base attenuate, slightly oblique; apex acuminate, gla- brous. Inflorescence central, with peduncle ob- scured within pseudostem; peduncle 11–15 cm long, to 3 mm in diameter, light green; spike 4–5 cm long, 2–3 cm in diam. at the widest position, with no obvious coma, composed of 5–6 bracts; bracts 3.5–4 cm long, 1.6–1.8 cm wide, broadly to narrowly ovate, whitish green at the base, green towards the apex, with numerous vertical striations, pubescent at apex, base connate, apex acute to narrowly acute, reflexed, subtending 1–2 flowers; cincinni; bracteoles one per flower, ovate, 1.6–1.8 mm long, 8–9 mm wide, apex acuminate, glabrous. Flowers 5–5.5 cm long, exserted from bracts; calyx 0.9–1 cm long, toothed, with a unilateral incision, glabrous, translucent white; floral tube 2.5–3 cm long, narrowly cylindrical at base, funnel-shaped at apex, whitish; dorsal corolla lobe 2 cm long, 1.2 cm wide, triangularly ovate, glabrous, apex acute; lateral corolla lobes 1.6–1.7 cm long, 8–9 mm wide, ovate, apex obtuse, translucent white, glabrous; labellum 2–2.2 cm long, 1.7–1.8 cm wide, slightly obovate, with an incision 3–4 mm long, light yellow with bright yellow raised band running through the center; lateral staminodes 1.5–1.7 cm long, 0.5–0.6 cm wide, unequally oblanceolate, light yellow, glabrous on both sides. Stamen 1.3–1.4 cm long; filament 1– 1.2 cm long, 5–6 mm wide at base, 1.5 mm wide at the point of connection to connective, light yellow, glabrous; anther oblong, slightly L- shaped in side view, light yellow, anther crest present, 1 mm long, emarginate at apex, white, spurred, anther spurs, ca. 2 mm long, filamen- tous, gently curved inward, light yellow; thecae 3 mm long, dehiscing along entire length, pollen white. Epigynous glands two, creamy yellow, 4 mm long, ca 0.8 mm in diameter, apex subu- late. Style white, glabrous; stigma capitate, ca 1 mm wide, white; ostiole glabrous. Ovary 4–5 mm long, ca. 2 mm wide, trilocular, brownish, densely pubescent. Fruit and seeds unknown.

Etymology.—The specific epithet refers to the stoloniferous rhizomes, one of the distinctive morphological characteristics for this species.

Distribution.—Thus far known only from the edge of the subtropical evergreen forest, 2020] TANAKA ET AL.: CURCUMA STOLONIFERA (ZINGIBERACEAE)

along the Nam Ei Zu River, Upper Chindwin, in the Htamanthi Wildlife Sanctuary, Sagaing Region, northwestern Myanmar (Fig. 3).

Habitat, ecology and penology.— Occurring in sunny openings at the edge of subtropical ever- green forest. Flowering from September to Octo- ber. Fruits not seen, and fruiting period unknown.

Conservation assessment.— This species is known from three locations in Htamanthi Wildlife Sanctuary (Fig. 3). The estimated EOO is about 200 km2 and AOO is estimated at 30 km2 based on the current data. The extent of the populations remains unknown, but the sanctuary is a large protected area (2,150.73 km2) consisting of lowland tropical evergreen forest, and at least during the surveys, we did not see any deforestation or forest fragmentation. Curcuma stolonifera is assessed as Least Concern (LC) (IUCN, 2012, IUCN Standards and Petitions Committee, 2019).

Additional specimens examined: MYANMAR. Sagaing Region: Basin of Chindwin River, Htamanthi Wildlife Sanc- tuary, Nam Ei Zu, Hkamti Township, 150 m elevation, 25.29614°N, 95.25988°E, 20 Oct 2014 [fl], M. M. Aung et al. 43 (NY [NY02648545], RAF); loc. cit., 25°30′12”N, 95°30′ 12′′E, 11 Sep 2016 [fl], N. Tanaka et al. MY812 (TNS [TNS01283483], RAF).

Acknowledgements

This study was carried out by the integrat- ed research project “Biological Inventory with special attention to Myanmar” initiated by the National Museum of Nature and Science, Japan based on an MoU between NMNS and Forest Department, Ministry of Natural Resources and Environmental Con- servation, Myanmar, and also partially sup- ported by JSPS KAKENHI Grant Number 15K07207 and 18KK0210 (to N. Tanaka). This research was also made possible by a grant from the Leona M. and Harry B. Helmsley Charitable Trust to the New York Botanical Garden. We are grateful to the Myanmar Forest Department, Ministry of Natural Resources and Environmental Conservation for their permission to carry out fieldwork in protected forests, and for their support and collaboration. We thank Dr. Douglas Daly for providing a photograph.

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