KAEMPFERIA JENJITTIKULIAE ( KAEMPFERIA SUBG. PROTANTHIUM : ZINGIBERACEAE), A NEW, ENDANGERED SPECIES ENDEMIC TO THAILAND

from Central–Northeastern Thailand, is described and illustrated. The diagnostic characters of this novel taxon are discussed and compared with those of the morphologically similar species Kaempferia lopburiensis , K. rotunda and K. udonensis . Detailed photographs of plants and dissected flowers, and information on phenology, distribution and ecology, are provided. A preliminary IUCN conservation assessment of Critically Endangered (CR) is assigned.

Introduction usually separated from the pseudostem. The inflorescences emerge from the ground before the leafy shoot arises, giving these plants the common name dok din in Thai ('earth flower') (Nopporncharoenkul & Jenjittikul, 2018).
Taxonomically, two main types of floral plane, namely perpendicular and parallel to the ground, have been used as effective characteristics for distinguishing the species in Kaempferia subg. Protanthium (Nopporncharoenkul et al., 2020). The perpendicular type of floral plane is characterised by upright to slightly arcuate lateral staminodes and a deflexed distal half labellum; it is generally found in K. aurora, K. graminifolia, K. kamolwaniae, K. noctiflora, K. rotunda and K. simaoensis (Nopporncharoenkul et al., 2020;Wongsuwan et al., 2020). The parallel floral plane is characterised by a T shape formed by the horizontal staminodes and labellum, which are arranged in the same plane and parallel to the ground. The species with this latter type of floral plane are K. albiflora, K. caespitosa, K. grandifolia, K. lopburiensis, K. takensis, K. udonensis and K. xiengkhouangensis (Boonma et al., 2020;Nopporncharoenkul et al., 2020).
The new taxon that we describe here, Kaempferia jenjittikuliae, is a strict endemic of limestone in the Phetchabun Province of Central-Northeastern Thailand. It has very large adpressed leaves like those of Kaempferia lopburiensis and K. udonensis, but the flower is of the perpendicular floral plane type. We have carried out an intensive morphological study of living material from the type locality, in both flowering and vegetative phases, including comparison with protologues and herbarium specimens deposited at the main herbaria in Thailand, and found that these characters do not co-occur in any known species of Kaempferia subg. Protanthium. It is therefore with confidence that we taxonomically characterise and identify it as a species new to science. A preliminary conservation status of Critically Endangered (CR) is assigned, based on the IUCN Red List Categories and Criteria, version 14 (IUCN Standards and Petitions Subcommittee, 2019). The description of this novel taxon makes use of the technical terms in the Kew Plant Glossary (Beentje, 2016). The N. Nopporncharoenkul et al. 3 diagnostic characters are clearly discussed in relation to the morphologically closest taxa. Furthermore, an updated key to the species of Kaempferia subg. Protanthium is provided.
Distribution. Kaempferia jenjittikuliae is strictly endemic to the limestone area of Chon Daen District, Phetchabun Province, Central-Northeastern Thailand.
Ecology. It grows in fine loam soil with rocks under semi-shaded mixed deciduous forest with bamboo, close to the foothills at 250-270 m a.s.l.
Phenology. Flowering starts at the beginning of the rainy season (April) and lasts until mid-May. Fruit and seeds mature in late May. Leafy shoots usually emerge in mid-May. The plants enter dormancy in November.
Provisional IUCN Red List category. This endemic species is known only from the type locality in Chon Daen District, Phetchabun Province. The area of occupancy (AOO) is estimated to be less than 4 km 2 , where it occurs as two small subpopulations with few mature individuals (fewer than 300 plants). Currently, the suitable habitats, especially the limestone area in Phetchabun and adjacent provinces in Central Thailand, are severely fragmented geographically and continue to decline in area due to quarrying for the construction industry (limestone and cement materials) and urban development. Moreover, the type locality is not under any legal protection and the population is at the edge of a forest and a cassava plantation. It is likely to be directly threatened by expansion of agriculture contributing to the deterioration of the population. The current information on the AOO and population size leads us to provisionally propose that Kaempferia jenjittikuliae be treated as Critically Endangered (CR B1ab (i, ii, iii, iv) + B2ab (i, ii, iii, iv)), in accordance with the IUCN Red  Kaempferia jenjittikuliae has the largest adpressed foliage of any species belonging to subg. Protanthium. It is closely similar to Kaempferia lopburiensis and K. udonensis morphologically. They share the huge size of the broadly ovate to suborbicular leaves lying flat on the ground (Figure 4). These three species can be easily distinguished, however, by their floral planes as well as by differences in the position of the lateral staminodes and labellum. Kaempferia jenjittikuliae has a perpendicular floral plane with upright to slightly arcuate staminodes and a deflexed distal half labellum; in contrast, the lateral staminodes and labellum of K. lopburiensis and K. udonensis are horizontal, arranged in the same plane, and usually parallel to the ground (Table, see Figure 4B,E). In its floral shape, Kaempferia  jenjittikuliae also resembles K. rotunda, but the differences in habit and the shape of the lamina distinguish the two species fairly clearly. The large adpressed leaves of Kaempferia jenjittikuliae differ obviously from the upright leaves of K. rotunda (see Table, Figure 4). During our observations in the type locality, we found good fruit set with numerous viable seeds at the end of the flowering season. This evidence indicates that Kaempferia jenjittikuliae has high fertility and sexual productivity in its natural habitat. 3a. Leaves ovate to broadly elliptic, green to deep purplish red, usually with a deep purplish red patch towards the midvein; lateral staminodes upright to slightly arcuate; labellum deflexed distal half with incision around half of its length; labellum base flat K. noctiflora 3b. Leaves elliptic, lanceolate-oblong to narrowly lanceolate, green; lateral staminodes and labellum horizontal, arranged in the same plane; labellum with incision up to two-thirds of its length; labellum base involute, enclosing the anther __________________ K. albiflora 4a. Floral plane perpendicular to the ground; staminodes upright to slightly arcuate; labellum deflexed distal half with incision around half of its length __________________ 5 4b. Floral plane parallel to the ground; lateral staminodes and labellum horizontal, arranged in the same plane; labellum with incision more than two-thirds of its length ________ 10 5a. Leaves adpressed to the ground, broadly ovate to suborbicular ________ K. jenjittikuliae 5b. Leaves upright; linear, narrowly lanceolate, lanceolate-oblong, elliptic to ovate _______ 6 6a. Leaves linear grass-like to narrowly lanceolate-oblong, less than 5 cm wide K. graminifolia 6b. Leaves lanceolate-oblong, elliptic to ovate, more than 5 cm wide ____________________ 7 7a. Labellum with two conspicuous yellow bands from base towards sinus; anther crest obtuse to trilobed-undulate, the middle lobe more elongated than side lobes K. simaoensis 7b. Labellum with a white or pale yellow band from base towards sinus, usually surrounded by purple stripes; anther crest bilobed to tridentate _____________________ 8 8a. Anther crest tridentate; epigynous gland 8-12 mm long; colour of wilted staminodes and labellum brownish orange _____________________________________________ K. aurora 8b. Anther crest bilobed, usually with 1-3 small teeth or lobes between the main lobes; epigynous gland 2-6 mm long; colour of wilted staminodes and labellum white with deep purple to blue ________________________________________________________________ 9 9a. Leaves petiolate; ligule less than 5 mm long ______________________________ K. rotunda 9b. Leaves sessile; ligule 6-9 mm long __________________________________ K. kamolwaniae 10a. Leaves upright, oblong, elliptic to ovate ___________________________________________ 11 10b. Leaves adpressed to the ground, broadly ovate, suborbicular to orbicular ___________ 13

Key to the species of
11a. Lateral staminodes pure white; labellum white with a pale yellow patch from base towards sinus _________________________________________________________ K. caespitosa 11b. Lateral staminodes light pink to purple; labellum light pink to purple with two large darker pink to deep purple spots at sinus _________________________________________ 12 12a. Leaves sessile, green __________________________________________ K. xiengkhouangensis 12b. Leaves petiolate, green usually with 1-3 layers of white to pale light green variegation K. takensis 13a. Labellum with a white patch from base towards sinus _________________ K. lopburiensis 13b. Labellum without a white patch from base towards sinus ________________ K. udonensis