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| Colocasia sookchaloemiae Chatan & Promprom, in Promprom, Munglue, Pasorn, Lanorsavanh et Chatan, 2026. |
Abstract
Colocasia sookchaloemiae (Araceae) is described from Phu Pha Yol National Park (northeastern Thailand). It is morphologically similar to C. fallax, from which it differs in having seasonal dormancy (vs. evergreen), broader and non-glaucous laminae (vs. narrower and slightly glaucous beneath), a speckled green ovary (vs. mostly green), a convex stigma with a depressed center (vs. 3-lobed), a sparsely hairy sterile interstice (vs. glabrous), and a thicker stipitate appendix (vs. slender, often sessile, or shortly stipitate). A comparative study of living plants, cultivated specimens, and herbarium material (including types) supports its recognition as a distinct species. The new taxon grows on rocky cliffs in dry dipterocarp and mixed deciduous forests at 350–400 m a.s.l., and it is currently known from Mukdahan and Sakon Nakhon provinces. A preliminary IUCN assessment indicates that the species is Data Deficient (DD).
Key words: Asia, new species, taxonomy
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| Colocasia sookchaloemiae. A. Opened inflorescence with parts removed; B. Lower part of the spadix showing pistillodes at the base, pistillate flower zone, sterile interstice, and part of the staminate zone; C. Upper part of the spadix and appendix; D. Enlarged view of the lower part of the spadix; E, F. Staminate flower zone, stipe, and lower part of the appendix; G, H. Appendix and adaxial side of the spathe (showing dirty yellow to pale orange-yellow coloration near the apex). |
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| Colocasia sookchaloemiae. A–C. Habit and habitat. |
Colocasia sookchaloemiae Chatan & Promprom, sp. nov.
Diagnosis. Colocasia sookchaloemiae differs from C. fallax in having seasonal dormancy (vs. evergreen); broader (11–25 cm) and non-glaucous lamina [vs. narrower (3.5–15 cm) and slightly glaucous beneath]; larger (2.3–3.1 mm in diameter), speckled green ovary and a convex stigma with a depressed center [vs. smaller ovary (ca. 1.1 mm in diameter), stigma 3-lobed]; pistillate zone with basal rows of pistillodes (vs. rows of nail-/peg-like staminodes); sterile interstice and staminate zone sparsely hairy (vs. glabrous); sterile interstice shape cylindrical and slightly constricted (vs. tapering); appendix thicker, ivory, and clearly stipitate (vs. slender, often sessile/shortly stipitate, creamy-yellow to purple). Details of the morphological comparison between the new species and C. fallax are shown in Table 1.
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Wilawan Promprom, Phukphon Munglue, Pattana Pasorn, Soulivanh Lanorsavanh and Wannachai Chatan. 2026. Colocasia sookchaloemiae (Araceae), A New Species from northeastern Thailand. PhytoKeys. 269: 131-140. DOI: doi.org/10.3897/phytokeys.269.175203 [13 Jan 2026]
