Continued Botanical Exploration Uncovers a New Endemic Species of Curcuma subgen. Hitcheniopsis (Zingiberaceae) from Central Thailand

Continued botanical exploration in previously insufficiently surveyed areas of Saraburi Province, Central Thailand, revealed an undescribed member of Curcuma subgen. Hitcheniopsis. This study aimed to formally describe the taxon, assess its morphological distinctiveness, evaluate its phenetic relationships, and provide a preliminary conservation assessment. Morphological observations were based on living and freshly collected material, herbarium specimens, protologues, and comparative taxonomic sources. Phenetic relationships among 11 taxa were assessed using 34 morphological characters, the Gower coefficient, UPGMA clustering, and principal coordinates analysis (PCoA). The new species, Curcuma koonmeeana Saensouk, P.Saensouk & Boonma, is distinguished from morphologically allied taxa by a unique combination of fertile-bract architecture, poorly developed coma bracts, well-exserted flowers, labellum morphology and indumentum, yellow markings, and anther-crest configuration. Phenetic analyses summarized overall morphological relationships among the sampled taxa, with Curcuma charanii Boonma & Saensouk showing the greatest Gower similarity to C. koonmeeana. The species is currently known from two populations along the same limestone mountain range and is provisionally assessed as Vulnerable (VU D1). Its recognition increases the known native diversity of subgen. Hitcheniopsis in Thailand to 31 taxa, comprising 30 species and one natural hybrid. The discovery highlights the continuing value of targeted botanical exploration and the need for habitat and population conservation.