Curcuma ignea Ruchis. & Jenjitt., 2023

Ruchisansakun, Saroj & Jenjittikul, Thaya, 2023, CURCUMA IGNEA (ZINGIBERACEAE), A SPECTACULAR NEW SPECIES FROM THAILAND, Edinburgh Journal of Botany 80 (1959), pp. 1-8 : 2-6

publication ID	https://doi.org/ 10.24823/EJB.2023.1959
persistent identifier	https://treatment.plazi.org/id/039F87D7-FF81-2740-FFBC-F51EFC89FCA0
treatment provided by	Felipe
scientific name	Curcuma ignea Ruchis. & Jenjitt.
status	sp. nov.

Treatment

Curcuma ignea Ruchis. & Jenjitt. , sp. nov.

Similar to Curcuma glans K.Larsen & Mood but differs by having anther spurs pointing outwards (vs anther spurs divergent), remotely pilose corolla lobes (vs glabrous corolla lobes), and vivid red, green to white bracts (vs pale green to green, with red-veined bracts). – Type: Thailand, Tak province, Tha Song Yang district , 16 ix 2019 (fl.), Ruchisansakun & Thawara 1359 (holotype BKF; isotypes QBG, SLR). Figures 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 .

Rhizomatous perennial herb to 50 cm tall. Rhizome c.2.2 × 2 × 1.5 cm, ovoid, up to 11 nodes, cream externally, with brown decayed scales on each node, white internally, aromatic. Roots to 9 cm long, 1.5 mm in diameter, with tubers c. 3 cm long, 1.5 cm in diameter, ovoid to ellipsoid, cream externally, white internally. Pseudostem 16–30 cm long. Bladeless sheaths 1–3, 15 cm long, pale green, apex acute to obtuse, decayed at anthesis. Leafy shoot with 8–12 leaves; leaf sheaths 8–10 × 2.8 cm, light green, glabrous; ligule 2–6 × 11 mm, bilobed with an incision c. 3 mm long, semitranslucent greenish, turning brown; petiole 7–15 cm

long, 4–5 mm in diameter, canaliculate, light green, pilose; lamina 15–27 × 4–10 cm, ovate to elliptic, base cordate to round, apex acuminate, adaxially dark green, pilose, abaxially pale green, glabrous, midrib green. Inflorescence terminal; peduncle exceeding pseudostem by c. 5 cm, light green to white, pilose; thyrse c. 10 cm long, 5.2–5.5 cm in diameter in the middle, composed of 15–20 fertile bracts, no coma; bracts 3.5–4 × 2.5–3 cm, broadly ovate to lanceolate, connate for 1/3 to 1/2 from base, apex acute, vivid red, green, to white, puberulent on both sides; coma bract absent; cincinni with 1–3 flowers; bracteoles one per flower, to 15 × 9 mm (outer ones larger, inner ones gradually smaller), ovate to narrowly ovate, apex acute to hooded, base cuneate, semitranslucent white, adaxially glabrous, abaxially puberulent. Flowers 2.5 × 1.8 cm, 4.5 cm long, exserted from bracts; calyx

15–23 mm long, tridentate, with unilateral incision 2 mm, semitranslucent white, pilose; floral tube 28–31 mm long, 2.5–3 mm in diameter, bent 22 mm from base, narrowly cylindrical at base, funnel-shaped distally, white, sparsely pilose; dorsal corolla lobe 17–19 × 5–6 mm, elliptic to ovate, apex hooded, mucronate, white to red, glabrous to scattered pilose; lateral corolla lobes 15–17 × 4.5–5 mm, elliptic to oblong, apex obtuse, white to red, glabrous to scattered pilose; labellum 17 × 9 mm, obovate, bilobed, with 6 mm deep incision, white with yellow band at the centre, with two red lines, puberulous; lateral staminodes 14–15 × c. 5 mm, narrowly ovate to narrowly obovate, apex obtuse, white to cream, with or without red patches or red V-shaped mark at base, sometimes with yellow tip, puberulous; stamen c. 15 mm

long; filament 5–5.5 mm long, 3–4 mm broad at base, c. 2 mm broad at point of attachment, white, puberulous; anther 10–14 × 2–3 mm, ovoid, white to cream, dorsally puberulous; anther spurs 2.5–4 mm long, pointing outwards (making the anther appear as L-shaped), apex acute, pale yellow, puberulous; anther crest 1.5–2 mm, round, bi- to trilobed, apex round; epigynous glands 4–6 × 1 mm; style 45 mm, white; stigma capitate, c. 1 mm long and wide, white to pale green; ovary 2–3 × 1.5–2 mm, ovoid, trilocular, pilose. Fruit not known.

Distribution. Thailand. Found in Tak province: Tha Song Yang district and Umphang district, and Nakhon Sawan province: Mae Wong district.

Habitat and ecology. Growing in shaded areas in mixed deciduous forest in limestone areas. Altitude 130– 190 m. Flowering August to October, fruiting estimated around October to November.

Etymology. The specific epithet, ignea , means ‘fiery’, referring to the vivid red-bracted inflorescence in the most common form of this species.

Vernacular name. Krachiao fai (กระเจียวไฟ) means ‘fire siam tulip’ and is proposed by the authors.

Proposed IUCN conservation category. Endangered (EN B1ab(iii,v)+B2ab(iii,v)). Curcuma ignea has an estimated extent of occurrence of 4716 km 2 and area of occupancy of 20 km 2 (GeoCAT, Bachman et al., 2011). It is known from four localities in Thailand: two in Tak province, c. 280 km apart, and two in Nakhon Sawan province, c. 25 km apart. It is recorded very close to the Myanmar border and is possibly found there also. In Thailand the localities in Tak province both had <100 individuals in each population. In Nakhon Sawan province, the occurrence data were confirmed from photographs, and no estimate of population size was possible. None of the localities in which the species is recorded has any protection, and all localities were disturbed by maize agriculture. New species in this genus are collected, sometimes to extinction, by unscrupulous plant hunters to sell as ornamental plants. This represents an increasing threat to new species, and for that reason the authors have not given detailed locality information. The species is, therefore, assessed as Endangered based on IUCN criteria ( IUCN Standards and Petitions Committee, 2022).

Notes. Curcuma ignea differs from other species in Curcuma subg. Ecomatae by the combination of open flowers and an L-shaped anther. It is similar to Curcuma glans , C. ecomata Craib and C. flammea Škorničk. , with which we compare the new species in the Table. The most similar species is Curcuma glans , but C. ignea differs from that species by having anther spurs pointing outwards (vs anther spurs divergent), remotely pilose corolla lobes (vs glabrous corolla lobes), and vivid red, green, to white bracts (vs pale green to green, with red-veined bracts). In Thailand, Curcuma ignea has been confused with C. rubrobraceteata Škorničk. and C. cinnabarina Škorničk. & Soonthorn because those species also have elongated inflorescence with red bracts.