Wednesday, February 12, 2020

[Botany • 2020] Curcuma papilionacea (Zingiberaceae) ปทุมมาถิ่นใต้ • An Unusual New Species from southern Thailand

Curcuma papilionacea Soonthornk., Ongsakul & Škorničk. 

in Soonthornkalump, Ongsakul, Dolaji & Leong-Škorničková. 2020.
ปทุมมาถิ่นใต้  || DOI: 10.11646/phytotaxa.432.1.2

Curcuma papilionacea, an unusual new species of Curcuma subgenus Hitcheniopsis (Zingiberaceae) is described and illustrated here. It is known only from Satun province in southern Thailand, and is easily distinguishable among all species of subgenus Hitcheniopsis by its inflorescence of green bracts and pea-like flowers with a small labellum and very prominent lateral staminodes. It also has prominently developed anther spurs, a character not yet recorded in this subgenus. It is compared to the four morphologically closest species which are Curcuma alismatifolia, C. harmandii, C. rhabdota and C. saraburiensis. A preliminary IUCN conservation assessment of Critically Endangered (CR), and notes on its distribution and ecology are also provided.

Keywords: Curcuma alismatifolia, C. harmandii, C. rhabdota, C. saraburiensis, C. subgenus Hitcheniopsis, Satun province, Monocots

FIGURE 2. Curcuma papilionacea Soonthornk., Ongsakul & Škorničk.
A–B. Inflorescence. C. Flower (semi-top view). D. Inflorescence (top view). E–G. Flower viewed from different angles.
 Photographed by S. Soonthornkalump, A. Dolaji and A. Ongsakul.

Curcuma papilionacea Soonthornk., Ongsakul & Škorničk. sp. nov.
subgen. Hitcheniopsis.

 Curcuma papilionacea is unique in the genus by the following combination of characters: absence of epigynous glands, presence of L-shaped anthers, inflorescences composed of green bracts without coma, and flowers with a pea-like appearance. 

Distribution and ecology:— Known only from Satun province in southern Thailand. It grows in sandy clay loam at the edge of disturbed forest and rubber tree plantations. Some populations were found in humus pockets in limestone under semi-shade at 0–50 m a.s.l.

Etymology:— The specific epithet is derived from Latin ‘papilionaceus’, which means butterfly-like. It refers to the pea-like appearance of the flower. 

Vernacular names and uses:— No uses were reported, except occasional sale of the plant as an ornamental. As this species is likely to become more widespread in horticulture we propose Thai vernacular name Pathumma-Thin-Tai (Bpà-Tum-Maa-Tìn-Dtâi; ปทุมมาถิ่นใต้) [Pathumma = the Thai common name for Curcuma species, Thin-Tai = native to the southern part of Thailand].

Note:—As mentioned in the diagnosis, this species is very easy to distinguish from all other species of Curcuma by its pea-like flower. By its flower colour, which combines violet, dark red, white and yellow, it resembles three species in subgen. Hitcheniopsis, namely C. rhabdota, C. saraburiensis and C. alismatifolia Gagnep. With the first two species, it also shares the prominently plicate leaf blades, but it is easily distinguished from both of them by its inflorescences with no coma. From C. alismatifolia, it can also be distinguished by the lack of coma bracts, and plicate leaves (compared to narrowly elliptic and rather smooth leaf blades in C. alismatifolia). It may also be considered somewhat similar to Curcuma harmandii, which has inflorescences composed of green bracts without coma, but these bracts are very different in shape with narrowly acute apices, and the flowers are greenish white overall, with a yellow median band on a labellum bordered by a pink tinge, and narrowly oblong lateral staminodes. In addition, C. papilionacea occurs only in southern Thailand, while the above four species are confined to Central, Eastern and Northeastern Thailand.

Sutthinut Soonthornkalump, Annop Ongsakul, Aumdah Dolaji and Jana Leong-Škorničková. 2020. Curcuma papilionacea (Zingiberaceae), An Unusual New Species from southern Thailand. Phytotaxa. 432(1); 11–16. DOI: 10.11646/phytotaxa.432.1.2