Curcuma flammea Škorničk., 2014

Curcuma flammea Škorničk. View in CoL , sp. nov. — Fig. 2 View Fig

Similar to Curcuma bicolor Mood & K.Larsen , but differs in inflorescence with longer peduncles to 13 cm long (vs almost sessile inflorescence with peduncle c. 1.5 cm long), bracts white,pink to dark red (vs light green bracts with more or less reddish tinge and prominent veins), bright orange labellum with various degree of red ornamentation (vs mostly yellow-orange labellum with reddish to purple margins). — Type: Jana Leong-Škorničková, Tr ần Hṹu Đăng, Somsanith Bouamanivong, Khantheo Santhammavong, Udone Souvannakhoummane, Kittisack Phoutthavong JLS-1777 ( holotype SING (incl. spirit); isotype E, HNL, P), Laos, Vientiane Prov., Vang Vieng Dist., Ban Phou Din Deng, 467 m asl, N18°57'43.2" E102°26'09.9", 23 June 2012.

Etymology. The specific epithet is Latin for fiery or flaming. It is given on account of the bright orange-red colours of the flowers and bracts, which resemble flames on the forest floor when in full bloom.

Herb to 70 cm tall. Rhizome ovoid, c. 1–1.5 by 0.8–1.2 cm, with thin branches c. 3–6 mm diam, brown externally, light yellow internally, slightly aromatic with bitter smell; root tubers elliptic, c. 3.5 by 2 cm, light brown externally, pure white internally with translucent white centre, distanced 5–15 cm from rhizome. Leafy shoot to 90 cm long with 1–5 leaves when flowering; pseudostem to 30 cm long, composed of leaf sheaths; leafless sheaths decayed at anthesis; leaf sheaths white green or with pink tinge at base turning green towards the apex, densely puberulent; ligule 3–5 mm long, bilobed, lobes round, hyaline, greenish white, translucent, hairy; petiole 6–27 cm long (petiole of first leaf shortest, innermost leaves longer), canaliculate, green, densely puberulent; lamina elliptic, broadly elliptic to elliptic-ovate, to 36 by 17 cm, prominently plicate, adaxially bright green, shortly hairy along main veins, abaxially lighter green, shortly puberulent; midrib glabrous, green; base cordate; apex acute, c. 5–10 mm long. Inflorescence central (often breaking through the pseudostem) or rarely lateral (both can occur on the same plant), many-flowered; peduncle 3–13 cm long, to 7 mm diam, cream-white; spike 4–9 cm long, c. 3 cm diam in the middle, without coma; fertile bracts 7–24 per inflorescence, 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 to light green at base with various degree of red tinge throughout the bract (resulting in very light pink, light red to deep red bracts; the colour of the bracts is consistent within a spike, but varies within a population), very sparsely puberulent outside, glabrous inside, connate in the lower 1/2 to 1/3; enclosing cincinni with 3 flowers at the base of the inflorescence, 1–2 flowers at the top; bracteoles strongly reduced, one per flower, ovate, boat-shaped, c. 1–2 by c. 1 mm (outer ones larger, inner ones gradually smaller or totally absent), hyaline, translucent white, glabrous. Flowers 6.5–7.5 cm, much exserted from the bracts; calyx to 22 mm long, 3-toothed, unilaterally split c. 8–10 mm, translucent white with more or less red tinge especially distally, sparsely puberulent; floral tube c. 4–5 cm long, externally white at the base, with rich red tinge at the apex, densely puberulent, internally white to very light orange, puberulent with dorsally placed groove holding the style; dorsal corolla lobe 22– 25 by 9 –11 mm, triangular ovate, concave, with sides rolled inwards, glabrous, red outside, light red inside, apex mucronate, mucro c. 2 mm; lateral corolla lobes 20–21 by 8–9 mm, triangular ovate with sides rolled inwards, concave, glabrous, red on outside, light red on inside; labellum 21–25 mm long, 7–9 mm broad at basal 1/3, then diamond-shaped in distal 2/3, c. 16–21 mm at widest point, apex bifid with an incision to 8 mm long, base of the labellum light orange with dark red lines, middle and apical part of the labellum orange at apex and margin, with dark red tinge towards the lower part, with deep orange band marked with dark red line on the outside running through the centre (median band); lateral staminodes 20–22 by 10–13 mm, rhomboid, bright red in basal half, orange at apex, glabrous outside, with short glandular hairs present on the middle part facing the centre of the flower. Stamen 16–17 mm long; filament 7–8 mm long, orange with red tinge, 4 mm broad at base, 2 mm broad at apex (the point of attachment to the connective), covered with glandular hairs; anther c. 14 mm long, spurred, connective light orange, densely covered with short glandular hairs; anther spurs 3–4 mm long, narrowly triangular with sharp tips pointing outwards; anther crest thick, rounded, c. 1.5 mm long and c. 2 mm broad at base, orange; anther thecae 9 –10 mm, dehiscing along their entire length. Epigynous glands 2, c. 5–6 mm long, c. 0.6 mm diam, light yellow at base, darker at apex. Style thin, white, glabrous, placed in a groove in dorsal side of floral tube; stigma c. 1.5 mm long, 1.5 mm wide, white, ostiole ciliate, facing upwards. Ovary 2–3 by 2–2.5 mm, trilocular, densely hairy, hairs c. 0.2 mm long. Fruits not seen. Description based on living and spirit material of Leong-Škorničková et al. JLS-1777.

Distribution — Currently known only from the type locality.

Habitat & Ecology — Growing on steep limestone slopes covered with primary dipterocarp forest at 400–500 m asl.

Phenology — Flowering in the 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. Most Curcuma species in subg. Ecomata , especially from the alliance of C. bicolor , where this species belongs, tend to be fairly restricted in distribution. Accordingly, we estimate that the extent of occurrence is less than 20 000 km 2. While the habitat of this species is unsuitable for fast agricultural exploitation, the fact that Vang Vieng is a popular tourist destination and the type population is not in a protected area, continuing decline in area, extent and quality of habitat can be foreseen. Category Vulnerable VU B1ab(iii) is therefore proposed here. Further exploration of the area around Vang Vieng is needed to understand the situation better and amend the conservation status.

Notes — Curcuma flammea also belongs to subg. Ecomata . Morphologically, the most similar species are C. bicolor and C. rhomba Mood & K.Larsen. Preliminary molecular analyses of subg. Ecomata (Záveská et al. unpubl.) suggest that C. flammea is closer to C. bicolor than to C. rhomba .