Curcuma corniculata Škorničk., 2014

Phathavong, K., 2014, Three new ginger species (Zingiberaceae) from Laos, Blumea 59 (2), pp. 106-112 : 106-108

Curcuma corniculata Škorničk. , sp. nov. — Fig. 1

Similar to Curcuma glans K.Larsen & Mood , but differs in the red corolla lobes (vs white or white with a reddish tinge),bright orange,diamond-shaped labellum with horn-like tips curving outwards (vs obovate white labellum with golden yellow median band and apex) and bright orange lateral staminodes with dark purple patch at the base (vs white lateral staminodes with purple base and golden yellow apex). — Type: Jana Leong-Škorničková, Tr ần Hṹu Đăng, Otakar Šída, Udone Souvannakhoummane & Kittisack Phoutthavong JLS-1752 (holotype SING (incl. spirit); isotype E, HNL, P), Laos, Louangphrabang, Ban Long Lao Mai, 866 m asl, N19°45'16.6" E102°02'56.7", 20 June 2012.

Etymology. The specific epithet ‘ corniculata ’ is derived from Latin and means small horns, in reference to the horn-like tips of the labellum.

Herb to 1 m tall. Rhizome ovoid, c. 1.5–3.5 by 0.8–1.5 cm, with thin branches (c. 3–6 mm diam), brown externally, light yellow internally, slightly aromatic; root tubers elliptic, 3–5.5 cm long, light brown externally, pure white internally with translucent white centre, distanced 5–15 cm from rhizome. Leafy shoot with 5–9 leaves when flowering; pseudostem to 35 cm long, green, composed of leaf sheaths; leafless sheaths perhaps two, decayed at anthesis; leaf sheaths green, puberulent; ligule 5–11 mm long, bilobed, hyaline, greenish white, translucent, puberulent; petiole 10–35 cm long (petiole of first leaf shortest, innermost leaves longer), canaliculate, green, shortly sparsely hairy; lamina broadly elliptic to elliptic-ovate, to 47 by 22 cm, prominently plicate, adaxially bright green, sparsely shortly hairy along main veins, abaxially lighter green, glabrous; midrib glabrous, green; base cordate; apex acute, c. 1–1.5 cm long, puberulent. Inflorescence lateral, many-flowered; peduncle 4 –15 cm long, to 1 cm diam, cream-white, with up to 5 sheathing bracts (mostly decayed, 1–8 cm long); spike 7–11 cm long, c. 4–6 cm diam in the middle, without coma; fertile bracts 20–30 per inflorescence, bract 3–6 by 1.2–3.3 cm (larger at the base of the inflorescence), ovate to trullate, smaller and ovate at the apex, whitish at base to light green at apex with various degrees of red tinge throughout the bract (resulting in light red to deep red bracts, colour varying within population), both surfaces shortly pubescent, connate in the lower 1/2 to 1/4; enclosing cincinnus with 3 flowers at the base of the inflorescence, 1–2 flowers at the top; bracteoles much reduced, one per flower, ovate, boat-shaped, c. 1–2.5 mm by c. 1 mm (outer ones larger, inner ones gradually smaller), hyaline, translucent white, glabrous. Flowers 6.5–8 cm, much exserted from the bracts; calyx to 21 mm long, 3-toothed, unilaterally split to c. 6–8 mm, translucent white or with slight red tinge at upper part, sparsely hairy or glabrous; floral tube c. 4–5.5 cm long, externally white at the base, with red tinge at the apex, densely puberulent, internally white, sparsely puberulent with dorsally placed groove holding the style; dorsal corolla lobe 22–27 by 7–9 mm, triangular ovate, concave, with sides rolled inwards, glabrous, red outside, light red to white inside, apex mucronate, mucro c. 2 mm, with a few short hairs; lateral corolla lobes 21–24 by 7–8 mm, triangular ovate with sides incurved, concave, glabrous, red outside, light red to white inside; labellum 23–25 by 16–20 mm, diamond-shaped, margins recurved, apex bifid with an incision up to 14 mm long and strongly recurved horn-like lobes, base of the labellum light orange with two orange lines in the centre and often with slight purple tinge laterally, middle and apex of the labellum light to deep orange at the margin, with deep orange band running through the centre (median band); lateral staminodes c. 22–24 by 8–10 mm, slightly rhomboid with sides flexing outwards, bright orange with 3–4 mm at base tinged dark purple (sometimes missing), sparse, short glandular hairs present on both surfaces. Stamen 18–20 mm; filament 8–9 mm long, white with purple tinge towards base, 2.5–3 mm broad at base, 1.5 mm broad at apex (the point of attachment to the connective), covered with dense, very short, glandular hairs; anther c. 13–15 mm long, spurred, connective light yellow to very light orange, densely covered with short glandular hairs; anther spurs c. 3 mm long, triangular with sharp tips, pointing outwards; anther crest thin, rounded, c. 1.5 mm long and c. 1 mm broad at base, orange; anther thecae 9 –11 mm long, dehiscing along their whole length. Epigynous glands 2, c. 4–6 mm long, 0.3–0.5 mm diam, cream-white. Style thin, white, glabrous, held in groove in dorsal side of floral tube; stigma c. 1 mm long, 0.8 mm wide, white, ostiole ciliate, facing upwards. Ovary 2–3 by 2–2.5 mm, trilocular, densely puberulent, hairs c. 0.2 mm long. Fruit a globose trilocular capsule, c. 1 cm diam, white, puberulous; seeds irregularly obovoid, 4–7 mm long, light brown, shiny, enclosed in translucent white, laciniate aril. Description based on living and spirit material of JLS-1752.

Distribution — Endemic to Laos, currently known only from the type locality.

Habitat & Ecology — Growing in bamboo vegetation on limestone outcrops, at 800–900 m asl.

Phenology — Flowering in early rainy season, end May to July, flowers last a single day, open in the morning and closing in late afternoon. Fruiting June to July (August?).

Conservation status — Specimen records exist so far only from the type locality. Local people who were interviewed and shown images of this species, reported that it occurs in various areas adjacent to Louangphrabang. The number and size of the populations are, however, not yet exactly known. Most Curcuma species in subg. Ecomata , especially those allied to C. bicolor Mood & K.Larsen , where this species belongs, tend to be fairly restricted in their distribution. Accordingly, we estimate that the extent of occurrence is less than 20 000 km 2. The type population is not in a protected area and is used for cultivation of maize ( Zea mays L.), groundnuts ( Arachis hypogaea L.) and other crops, therefore continuing decline in area, extent and quality of habitat can be foreseen. Category Vulnerable VU B1ab(iii) is, with caution, proposed here. Further exploration of the region is needed as this species may be Endangered or Critically Endangered soon.

Notes — Curcuma corniculata belongs to the recently established subg. Ecomata ( Záveská et al. 2012) . The two most closely related species in this subgenus are C. glans and C. bicolor . It may be fairly difficult to determine dried herbarium specimens but there is no confusion when living, flowering material is available (see Mood & Larsen 2001) or when there are appropriate notes or photographs accompanying specimens. Also, if a spirit specimen is present, confusion is not likely. Among these species, C. corniculata can be readily recognised by its bifid labellum, with the two strongly reflexed horn-like lobes.

Figures

Fig. 1 Curcuma corniculata Škorničk. a. Habit; b. inflorescence; c. seeds; d. ligules; e. rhizome; f. flower dissection, with detail of stamen from side and front view (all from type: JLS-1752). — Scale bars: c, f (inset) = 1 cm; e, f = 2 cm. — Photos by Jana Leong-Škorničková.