Curcuma woodii N. H. Xia & J. Chen, 2015

Chen, Juan, Lindstrom, Anders J. & Xia, Nian-He, 2015, Curcuma woodii (Zingiberaceae), a new species from Thailand, Phytotaxa 227 (1), pp. 75-82 : 75-79

Curcuma woodii N. H. Xia & J. Chen , sp. nov.

Similar to Curcuma rhomba J. Mood & K. Larsen (subgen. Ecomata ) in several characters but differs in the leaf blades abaxially pubescent, the bracts whitish green, the labellum white with orange bands at the center, the lateral staminodes white with orange dots at the apex, and the ovary nearly glabrous.

Type:— China, Guangdong, Guangzhou, South China Botanical Garden (cultivated, introduced from Thailand), 28 September 2010, J. Chen & T. Wood 201010 (holotype: IBSC). Figs. 1 & 2 .

Herbs ca. 40–60 cm alt., perennial. Main rhizome slender, fibrous, multi-branched, 0.6–1 cm in diam., cream-colored inside; lateral rhizome creeping, slender, 0.6–1.0 cm in diam., white inside; root tubers ovate, white inside. Leafy shoots up to 60 cm tall, leaves 5; leaf sheaths green, pubescent; petioles 16–23 cm long, pubescent; ligules ca. 3 mm long, hairy on the margin; blades 26–30 × 9–12 cm, ovate to elliptic, green on both sides, adaxially glabrous, abaxially pubescent, base rounded, apex acuminate. Inflorescence terminal, ca. 4.5–5 × 4.5–5 cm; peduncles 2–3 cm long, pubescent; bracts ca. 2.5–3 × 3–3.5 cm, ovate to elliptic, whitish green, pubescent on both sides, apex obtuse; bracteoles absent. Flowers 4–4.7 cm long, exserted from the bracts, white. Calyx ca. 2 cm long, white, glabrous, 2-teethed. Corolla tubes ca. 3 cm long, white, pubescent; lateral corolla lobes ca. 1.4 × 0.5 cm, white to pinkish, glabrous; dorsal lobe ca. 1.5 × 0.6 cm, white, densely villous at throat. Lateral staminodes petaloid, ca. 1.5 × 0.9 cm, elliptic, white, deep orange dots at the top and deep purple dots at the base; labellum ca. 1.6 × 1 cm, suborbicular, unilaterally split for ca. 6 mm long, white, two deep orange bands at the center with deep purple lines at the base, 2-teethed. Filament broad, flat, white; anther ca. 9 mm long, white, crest ca. 1 × 1 mm, spur short, ca. 1 mm long, white. Ovary 2–4 mm long, nearly glabrous; stigma white, glabrous; epigynous glands 2, ca. 7 mm long, linear. Capsule subglobose, 3-valved, dehiscent; Seeds obovate, light brown, with white laciniate aril.

Molecular diagnosis:— The new species differs from all other species of Curcuma at the following nucleotide positions in the plastid matK gene, position 1008: Adenine not Guanine; in the plastid trnH-psbA spacer, position 102: Adenine not Thymine; 103: Guanine not Thymine; 109: Guanine not Thymine; 110: Adenine not Thymine; 184: Adenine not Cytosine; (Coordinates from Curcuma rhomba complete trnK region, GenBank accession no. JQ409668.1, matK gene from 780-2327; C. rhomba partial trnH-psbA spacer, Genbank accession no. JQ 409783.1) ( Table 1).

Cytology:— Chromosome numbers were counted in actively growing root tips from the cultivated plants at South China Botanical Garden. The root tips were pretreated with 0.002 M 8-hydroxyquinoline for 6 h and fixed in Carnoy I, then macerated in 1 N HCl at 60° C for 5 min, and stained in Carbol fuchsin. Metaphase chromosomes were observed and photographs were taken under the OLYMPUS BX41 microscope (Olympus, Tokyo, Japan).

The metaphase chromosomes were counted to be 2 n = 42 ( Fig. 2A ). The chromosomes of C. woodii were very small, ca. 1.5 μm in lengths. As a result of the small chromosome sizes, no clear morphological differences were observed. Centromeres were difficult to detect; thus, karyotype analysis was not performed.

Distribution and Habitat:— This species was purchased at the local wild plant market in Sae Kaeow, just at the border of Cambodia. Its natural range is unknown.

Phenology:— Flowering from July to September at South China Botanical Garden.

Etymology:— The specific epithet, ‘ woodii’, was named after Tom Wood, who brought this species to South China Botanical Garden. Tom Wood made a great contribution to collecting gingers from South Asia, Australia, America and Arica to South China Botanical Garden.

Notes:— This species is similar to C. rhomba by the inflorescence emerging from the base of the pseudostems and anther shape. Their major differences lie in the bracts color, the flower parts color and shape ( Table 2, Figs 1 & 2 ).

The flower shape of C. woodii is similar to C. pierreana Gagnepain (1907: 405) and C. peramoena . But this species is different from them by the leaf blades larger, the bracts whitish, the lateral staminodes white with orange dots at the apex and the ovary nearly glabrous ( Table 2).

Only a single specimen (D. J. Middleton et al. 1220, barcode No.: E00196143) deposited at Royal Botanical Garden Edinburgh (E) and collected from Kui Buri National Park in Prachuap Khiri Khan in Thailand on 19th August, 2002, is a possible match for C. woodii . However, to confirm the identity of this specimen, re-collection from Kui Buri National Park is needed.

Additional specimens examined (paratypes):— China, Guangdong, Guangzhou, South China Botanical Garden (cultivated, introduced from Thailand), 9 September 2013, J. Chen 201343 (IBSC).

Figures

FIGURE 1. Curcuma woodii N. H. Xia & J. Chen sp. nov. A. Inflorescence with rhizomes and leaves. B. Detail of leave. C. Inflorescence. D. Flower (dorsal view). E. Bract. F. Flower (lateral view). G. Calyx. H. Corolla dorsal lobes, lateral staminodes and anther. I. Corolla lateral lobes and labellum. J. Corolla dorsal lobe. K. Detail of lateral staminode. L.Anther (front view). M.Anther (lateral view). N. Ovary (cross section). O. Stigma. P. Epigynous glands and ovary. Q. Seed. Drawn by: Liu Yun-Xiao.

FIGURE 2. Curcuma woodii N. H. Xia & J. Chen sp. nov. A. Chromosome number 2n = 42. B. Flower dissection. C. Flowers. D. Detail of anther. E. Detail of stigma. F. Terminal inflorescence emerging from the base of the pseudostems. G. Whole plants showing leaves and terminal inflorescence. H. Rhizomes. I. Seeds.