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| Thismia dasyantha & Thismia velaris Dančák, Sochor & Hroneš, in Dančák, Hroneš, Sochor, Uvírová, Blažek, Yunoh et Yiing, 2025. |
Abstract
Thismia velaris and T. dasyantha (Thismiaceae), two new species from Sarawak (Malaysian Borneo), are described. Key distinguishing features, particularly in floral structure, are highlighted through comparative morphological analyses accompanied by illustrations. Additionally, phylogenetic relationships are assessed using molecular data, and both newly described species are placed within the broader evolutionary framework of Thismia. Both species, being characterized by vermiform roots and six free tepals of equal shape and size, are classified within Thismia sect. Thismia subsect. Odoardoa. Preliminary conservation assessments, following IUCN Red List criteria, suggest that both species may be at risk due to their restricted distributions and potential habitat threats. Through the discovery of T. velaris and T. dasyantha, the diversity and biogeographical patterns of Thismia in Borneo are further elucidated, emphasizing the need for continued exploration and conservation efforts.
Borneo, Dioscoreales, mycoheterotrophy, rainforest, taxonomy, Monocots
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| Thismia velaris. A. Habit of flowering plant. B. Outer view of stamens inside the dissected floral tube. C. Longitudinally dissected floral tube with inner view of stamens, transverse bars and style. Drawn by Nela Malá from Dančák & Sochor BOR30/23. |
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| Thismia velaris Dančák, Sochor & Hroneš, A–D. Overall appearance showing more (A, C, D) and less (B) common morphotypes. E. Top view of flower. F. Dissected floral tube with colourless transverse bars and showing the position of stamen tube and style with stigma. G. Outer view of stamen with lateral appendage which central part is elongated into membranaceous veil. H. Lateral view of stamen (the neighbouring connective cut off). I. Top of the supraconnective (viewed from inside) with three distinct lobes. J. Style and stigma. Photos by M. Sochor (A, C, E–J) from Dančák & Sochor BOR30/23 and M. Hroneš (B, D) from uncollected plants recorded at the same locality in 2024. |
Thismia velaris Dančák, Sochor & Hroneš, sp. nov.
Diagnosis:—Thismia velaris is externally similar to T. malayana but differs by floral tube colourless translucent between veins (vs. brown in the upper half), flat annulus (vs. outer margin of annulus prominently raised), having three triangular lobes on supraconnective apex (vs. five appendages of three different shapes and sizes), and the central part of the lateral appendage elongated into membranaceous veil exceeding the apices of the supraconnective lobes (vs. central part of the lateral appendage without the veil, not exceeding the apex of the supraconnective appendages).
Etymology:—The specific epithet is derived from the Latin word velum (veil, curtain), referring to the unique veil-like structure hanging from the lateral appendage of the stamen.
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| Thismia dasyantha. A. Habit of flowering plant. B. View of the flower from the top. C. Dissected floral tube showing outer view of stamens, style and reticulate structure on the inner surface of the floral tube. D. Dissected floral tube showing inner view of stamens, style and reticulate structure on the inner surface of the floral tube. Drawn by Nela Malá Dančák & Hroneš MDMH2023/32. |
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| Thismia dasyantha Dančák, Sochor & Hroneš, A–C. Overall appearance. D. Top view of flower. E. Distinctly verrucose flower bud and dissected floral tube showing position of stamen tube. F. Annulus with a hexaradial figure resembling a stylised outline of a flower on its inner margin. G. Outer view of stamen. H. Inner view of stamens. I. Style and stigma viewed from above. J. Fruiting plant with elongated pedicel and capsule. Photos by V. T. Blažek (A, I) and M. Hroneš (B, D, E, G, H) from Dančák & Hroneš MDMH2023/32 and M. Hroneš (C, F, J) from uncollected plants recorded at the same site in 2024. |
Thismia dasyantha Dančák, Sochor & Hroneš, sp. nov.
Diagnosis:—Thismia dasyantha is distantly similar to T. pallida but differs in annulus indistinct, flat, with opening ca. 1 mm in diameter (vs. annulus distinct, raised, with opening ca. 2 mm), the opening resembling a schematic outline of a hexamerous angiosperm flower (vs. opening circular), tepals basally connate, 2.5–3 mm wide at the base (vs. free, ca. 2 mm wide at the base), tepal appendages 10–14 mm long (vs. ca. 3 mm long), three appendages (vs. five appendages) on supraconnective apex, the middle appendage being the shortest (vs. the longest), and stigma lobes deeply bifid (vs. shallowly notched).
Etymology:—The specific epithet is derived from the Greek words dasýs, meaning “hairy” and ánthos, meaning “flower”, referring to the prominent verrucae present on the outer surface of the floral tube, ovary and the abaxial side of the tepals, which resemble hairs.
Martin DANČÁK, Michal HRONEŠ, Michal SOCHOR, Alena UVÍROVÁ, Vojtěch Tobias BLAŽEK, Siti-Munirah Mat YUNOH and Ling Chea YIING. 2025. Thismia velaris and T. dasyantha, Two New Species of Thismia section Thismia subsect. Odoardoa (Thismiaceae) from Sarawak, Malaysia. Phytotaxa. 715(2); 117-128. DOI: doi.org/10.11646/phytotaxa.715.2.2 [2025-08-19] Researchgate.net/publication/394545435_Thismia_velaris_and_T_dasyantha_two_new_species_of_Thismia_from_Sarawak_Malaysia
