Curcuma kayahensis Nob. Tanaka & M. M. Aung, 2019

Tanaka, Nobuyuki & Aung, Mu Mu, 2019, Taxonomic Studies on Zingiberaceae of Myanmar I: A new species of Curcuma (Subgenus Ecomatae) from Myanmar, Phytotaxa 387 (3), pp. 241-248 : 246

Curcuma kayahensis Nob. Tanaka & M. M. Aung , sp. nov. ( Figures 2–3 )

Diagnosis: —Similar to Curcuma rhomba in orange-red lateral staminodes and labellum of a rhombic shape, however, it differs in having rhizomes yellow inside, lower surface of lamina densely covered with silver scales, the inflorescence position central, light green bracts with red veins, and flowers with longer gently curved anther.

Type:— MYANMAR. Kayah State: near Kyat Limestone Cave, Kyat Gu Reserved Forest, Chikae, ca. 13 km E of Loikaw, Loikaw Township, 925 m elevation, 19°40’05” N, 97°20’05” E, 20 August 2017, Tanaka et al. 2555 (holotype TNS, isotypes E, RAF, SING).

Description: —Rhizomatous, perennial herb to 60 cm tall. Rhizome narrowly ovoid, light brown externally, creamy white internally, bearing fusiform root tubers, 1–1.5 cm long, 0.6–0.8 cm wide, light brown externally, whitish internally. Leafy shoots with 3–4 leaves at the anthesis; pseudostems 6–7 cm long, green, partially reddish, composed of sheathing bracts and leaf sheaths; sheathing bracts 3–5, green, glabrous; leaf sheaths light green, margin hairy; ligule up to 4 mm long, bilobed, membranous, greenish white, slightly reddish, pubescent; petiole 15–20 cm long, canaliculate, pale green, glabrous; leaf blade slightly unequal, ovate to elliptic, 20–40 cm long, 10–20 cm wide, plicate, adaxially bright green, sparsely puberulent along ribs, sparsely small silvery glands, abaxially dull green (silvery shining under the sunlight), covered with numerous silver scales; midrib green, glabrous; base obtuse to subcordate, slightly oblique; apex attenuate to acuminate, pubescent. Inflorescence central; peduncle 5–6 cm long, to 7 mm in diameter, white; spike 4–6 cm long, 4–5 cm in diam. at the widest position, with no obvious coma, composed of 10–20 bracts; bracts 3.5–4 cm long, 1.5–2 cm wide, broadly to narrowly ovate to rhombic, whitish to whitish light green towards the top, with numerous vertical lines, both sides glabrous, connate in lower position, apex acute to narrowly acute, reflexed, subtending 1–2-flower; cincinni; bracteoles one per flower, subulate, 4–5 mm long, glabrous. Flowers 5–6 cm long, exserted from bracts; calyx 1.8–2 cm long, 3-toothed, with unilateral incision, 8–9 mm, lower part hirsute, upper part glabrous, translucent white, slightly reddish tinged at apex; floral tube 3–3.5 cm long, narrowly cylindrical basally, funnel-shaped at apex, yellowish basally, reddish towards the mouth; dorsal corolla lobe 2 cm long, 5–6 mm wide, lanceolate to ovate, glabrous, apex acute; lateral corolla lobes 2–2.2 cm long, 5–6 mm wide, lanceolate, apex acute to obtuse, red, glabrous; labellum 2–2.5 cm long, 1.7–1.9 cm wide, trullate to rhomboid, with an incision 2–4 mm long, whitish yellow at base, yellow at apex with bright yellow raised band running through the center; lateral staminodes 2–2.5 cm long, 1.3–1.8 cm wide, unequally rhomboid, orange-yellow, lighter towards base, glabrous on both sides. Stamen 2–2.5 cm long; filament 1–1.3 cm long, pale yellow, 4–5 mm wide at base, 2–3 mm wide at apex, glabrous; anther gently curved, crescent-shaped, spurred, connective tissue yellow to pale orange-yellow, glabrous, anther spurs ca. 5 mm long, parallel with acute apices, yellow, anther crest 2.5–3 mm long, apex emarginate, yellow; thecae 7–8 mm long, dehiscing along entire length, pollen white. Epigynous glands two, creamy yellow, 5–6 mm long, ca 0.5 mm in diameter, apex sublate. Style white, glabrous; stigma capitate, ca 1 mm wide, creamy yellow; ostiole ciliate. Ovary ca. 3 mm long, ca. 2 mm wide, trilocular, white, densely pubescent. Fruit and seeds unknown.

Etymology:—The specific epithet refers to the name of the state in Southeastern Myanmar where this species were discovered. Kayah State had been closed for a long time due to its local political situation, and opened only recently to outsiders including foreign nationals.

Distribution:—So far known only from the type collection in Kayah State, Myanmar. It might be endemic to Myanmar.

Habitat, ecology and phenology:—Growing at the edge of tropical evergreen forest on limestone hill with Boesenbergia maxwellii Mood, L.M.Prince & Triboun ( Mood et al. 2013: 72) . Flowering from July to August. Fruits not seen, and fruiting period unknown.

Other specimens examined (paratype): MYANMAR. Kayah State: Kyat Gu Reserved Forest, Chikae, ca. 13 km E of Loikaw, Loikaw Township, 925 m elevation, 19°35’38.6” N, 97°20’58.1” E, 20 July 2015, Mu Mu Aung, Pyae Pyae Win, Miyal Aung Soe 127 (TNS, RAF).

Figures

FIGURE 2. Curcuma kayahensis Nob. Tanaka & M.M. Aung A. Inflorescence and underground parts forming tubers. B. Inflorescence on ground. C. Upper surface of leaf blade. D. Lower surface of leaf blade. E. Habit.

FIGURE 3. Floral parts of Curcuma kayahensis Nob.Tanaka & M.M.Aung A. Front view of flower. B. Side view of gently curved anther. C. Staminodes (from left: lateral staminodes, and labellum). D. Stamen in front view. E. Stamen in back view. F.Anther spurs. Scale bars: A-E in 1 cm, F in 5 mm.