Curcuma stahlianthoides (Zingiberaceae), a new species from northeastern Thailand dispersed by ants

Curcuma stahlianthoides, a new species of Curcuma subg. Hitcheniopsis (Zingiberaceae: Zingi­beroideae) from northeastern Thailand is described and illustrated here. The flower morphology of C. stahlianthoides resembles several other species formerly classified in the genus Stahlianthus, but the inflorescences are composed of up to 11 plain green fertile bracts, conforming to the typical inflorescence structure in the genus Curcuma. This combination of characters is similar to C. leonidii from Vietnam, to which it is compared for the diagnostic purposes. Previous molecular results indicate that Stahlianthus should be merged with Curcuma subg. Hitcheniopsis and C. stahlianthoides is the second species providing morphological justification to do so. A detailed description based on living flowering material, colour plates including the flower dissection, and notes on distribution, habitat and phenology are also provided. The status of Vulnerable is proposed for this species based on the IUCN guidelines and criteria. Observations on ant-aided seed dispersal of this species are reported and discussed within present knowledge of myrmecochory in gingers.