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Cornukaempferia argentifolia (Zingiberaceae), a new species from northern Thailand

: Cornukaempferia argentifolia , a new species of Zingiberaceae from northern Thailand, is described and illustrated along with photographs, notes on its distribution, ecology, and IUCN conservation status. An identification key to the species of Cornukaempferia Mood & K.Larsen in Thailand and a distribution map are also presented.


Introduction
Cornukaempferia Mood & K.Larsen was first established as a new genus of Zingiberaceae from Thailand with C. aurantiiflora Mood & K.Larsen as its type (Mood & Larsen, 1997). Subsequently, a second species, C. longipetiolata Mood & K.Larsen was published in 1999(Mood & Larsen, 1999. The latter has since been found to be quite common in the mountains of Phitsanulok province near the border of Thailand and Laos. A third species C. larsenii P.Saensouk was published in 2007, which was found in Phu Ruea and Na Haeo national parks, Loei province, Thailand (Saensouk et al., 2007), and also in Laos (Rakarcha et al., 2020). In 2019, two additional species from northern Thailand, C.
chayanii Yupparach & Wongsuwan and C. kamolwaniae Picheans., Yupparach & Wongsuwan were published (Yupparach et al., 2019). Vol. 31(4): 260-266 (2021) ISSN: 0971-2313 (Print edition) ISSN: 2582-2438 (Online edition) https://dx.doi.org/10. 22244/rheedea.2021.31.04.03 The authors are revising the genus Cornukaempferia for the Flora of Thailand project and during exploration of the diversity of the Zingiberaceae in Thailand, a morphologically distinct species of Cornukaempferia was collected. It did not match with any existing taxa, and is hence described, illustrated, and photographed below as a species new to science. A key to the species of Cornukaempferia in Thailand is provided for facilitating their identification.

Materials and Methods
Plant materials were collected from the field in Chattrakarn district, Phitsanulok province, northern Thailand, between 2018 and 2020. Living specimens and spirit specimens were used for making detailed morphological measurements. The living specimens have been planted at the Brio Garden herbarium and spirit-preserved specimens deposited at the KKU herbarium and Brio Garden herbarium. The living specimens were used for comparison and verification compared to living and dried specimens in herbaria in Thailand (BK!, BKF!, KKU!, QBG!) including the cultivated species at Brio Garden, and the protologues of all species in Cornukaempferia (Mood & Larsen, 1997;Mood & Larsen, 1999;Saensouk et al., 2007;Yupparach et al., 2019). A preliminary conservation assessment was made, based on the guidelines of IUCN Red List Categories (IUCN, 2019). Altitude determination from sea level was obtained from recorded tracks in the 'View-Ranger' application (Augmentra Ltd., Cambridge, UK).
Etymology: The specific epithet "argentifolia" is derived from two Latin words, "argenti" meaning "silver" and "folia" meaning "leaves" and refers to its silvery leaves. Conservation status: Villagers who live close to the locality report that C. argentifolia argentifolia has been continuously exploited and removed from its habitat for many years. According to our survey since 2018, we found only one locality with mature individuals of less than 1,000. The living plants of this species were also sold in online media and exported overseas too. Due to its popularity, and market demand this species was continuously smuggled out of the forest, such that it is prone to be negatively affected by human activities more than by natural droughts within a very short time and has an uncertain future. However, further fieldwork is needed to assess changes in population distribution and abundance of this taxa. According to IUCN Criteria, (IUCN, 2019), the species falls under the category Data Deficient (DD).
Notes: The coloured silver leaves of C. argentifolia makes it easily distinguishable from other species in the genus. It is mostly similar to C. larsenii in having equally sized epigynous glands (4 mm long), glabrous staminodes, and labellum on both surfaces but differs in having leaves adaxially silver above and reddish below, glabrous bracts, finely hairy corolla tube, obovate labellum, finely hairy filaments, bi-lobed calyx apex, and a yellow rhizome with yellow core. While C. larsenii has green leaves with few silvery markings above, sparsely hairy bracts, glabrous corolla tube, campanuloid labellum, glabrous filaments, tridentate calyx apex, and a yellowish white rhizome with yellow core. Cornukaempferia argentifolia is also similar to C. kamolwaniae, but can be readily distinguished by its silver coloured leaves. A morphological comparison of C. argentifolia and its allied species is given in Table 1, and a key to the species of Cornukaempferia is also provided for facilitating their identification.