﻿Studies on Typhonium (Araceae) of Thailand I: Typhoniumvinicolor, a new species from Khon Kaen Province, Northeastern Thailand

﻿Abstract Typhoniumvinicolor from Khon Kaen Province (Northeastern Thailand), is described and illustrated as a species new to science. Color plates, phenology, distribution, discussion of similar taxa, and conservation status assessment are provided.


Introduction
Typhonium Schott (1829) (Araceae Juss.) is a genus of tuberous (sometimes rhizomatous or stoloniferous), terrestrial, and seasonally dormant herbs that inhabit forest floors, rocky areas, wet sites, stream sides, and grassy places in tropical and subtropical humid and seasonal forests, as well as in agricultural land (Mayo et al. 1997;Low et al. 2020).Hay et al. (2022) transferred most of the Australian Typhonium species to Lazarum A.Hay, so, according to these authors Typhonium (sensu stricto) would refer to species mainly distributed in Indochina (see e.g., Low et al. 2020;Hay and Hein 2022).Among the genera of tribe Areae, Typhonium s.str. is the largest one, with more than 70 species (100 based on Boyce and Croat 2011;72 in POWO 2024).The highest species diversity of Typhonium is found in Thailand, with 32 species, 24 of which are endemic (Boyce et al. 2012).Later than Boyce et al. (2012), six new species have been described from Thailand (Galloway 2012(Galloway , 2015;;Hetterscheid 2013;Sookchaloem and Maneeanakekul 2018), increasing the total number of species in the country to 38.However, the current number of species occurring in Thailand is undoubtedly much higher (Boyce et al. 2012) During our botanical survey in Khon Kaen Province (Northeastern Thailand), an unknown species of Typhonium was collected by the second author (SS).After meticulously examining its morphology and comparing it with protologues and relevant literature, as well as with digitized type specimens from Thailand and neighboring countries, it became apparent that the collected specimen does not match any other known Typhonium species.Thus, we consider it to represent a taxonomic novelty, which is described and illustrated in the present paper.

Materials and methods
The measurements and descriptions were based on freshly collected and/or alcohol-preserved material, processed according to the methods established by Davies et al. (2023).The species description follows Hay and Hein (2022), while Araceae morphological terminology follows Mayo et al. (1997) implemented by the descriptive terminology of Beentje (2016).Relevant type specimens of Typhonium species from Thailand and neighboring countries were examined in different herbaria (A, AAU, B, BK, BKF, C, CAL, CMU, E, HITBC, K, KKU, KUN, L, M, MO, P, PE, QBG, SING, and WAG; acronyms follow Thiers 2024) through high-resolution images from https://plants.jstor.org/and Global Biodiversity Information Facility (GBIF) accessed from https://www.gbif.org.An assessment of conservation status was carried out following IUCN (2024), based on our current knowledge and the respective terminology on categories, criteria, and subcriteria.The photographs in the plate were taken with an iPhone 13 (iOS version 17.5.1,2021, Apple Inc., Cupertino, CA, USA).The figure in this study was created using Pixelmator Pro (Version 3.6.5,Archipelago, 2023, Pixelmator Team, Vilnius, Lithuania) on a MacBook Pro (13-inch, M1, 2020, Apple Inc., Cupertino, CA, USA).
Etymology.The specific epithet is derived from the Latin "vinicolor" (wine-coloured), referring to the reddish-purple abaxial surface of the leaves.

Phenology. Flowering time in May.
Distribution and habitat.The newly discovered species is found exclusively at its type locality in Khon Kaen Province (Northeastern Thailand).It thrives in shaded to semi-shaded areas of tropical deciduous forests at elevations ranging from 200 to 250 m a.s.l.The species shows optimal growth in sandy loam soil mixed with rocks.Conservation status.This new species is known exclusively from its type locality, and no sufficient information there is regarding potential threats to its habitat.In accordance with the Red List criteria of the IUCN Standards and Petitions Subcommittee (2024), we propose classifying this species as 'Data Deficient' (DD).Further research is necessary, as there is inadequate information to assess the conservation status of this species.Currently, data is limited regarding its distribution, with no details on population size, trends, or potential threats to its habitat.
Regarding spathe and spadix structures, the new species also resembles Typhonium huense V.D. Nguyen & Croat (Nguyen and Croat 1997), T. lineare Hett.& V.D.Nguyen (Hetterscheid and Nguyen 2001) and T. stigmatilobatum V.D.Nguyen (Nguyen 2008) from Vietnam.However, the latter three species differ from T. vinicolor by having horizontally flexed spathe limb at anthesis (vs.only the upper part of spathe limb reflexed and then strongly coiled at anthesis in T. vinicolor) and strongly arching, dark brown or violet, stipitate appendix (vs.erect or weakly arching, ivory, sessile appendix in T. vinicolor).A more detailed comparison between T. vinicolor and its morphologically allied species is presented in Table 1.