Tuesday, December 2, 2025

[Botany • 2025] Thismia selangorensis (Thismiaceae) • A New mitriform Species of Thismia sect. Geomitra from Selangor, Malaysia

 

Thismia selangorensis  Siti-Munirah & Gim Siew,  

in Siti-Munirah, Siew, Mat-Tahir et Azhar, 2025. 

Abstract
Thismia selangorensis, a distinct mitriform species of the mycoheterotrophic genus Thismia, is described herein. It was first discovered in a tree hole on a riverbank in Taman Eko Rimba Sungai Chongkak, Selangor, Malaysia. This new species is superficially similar to members of Thismia section Geomitra in that it has coralliform roots, inner tepals forming a mitre with three appendages on top, and stamens with a prominent dorsal rib. However, T. selangorensis differs from known species of T. sect. Geomitra in several morphological features, including the colour of the flowers, the shape of the mitre, the shape of the inner tepal lobes forming the mitre, and the presence of translucent reticulation on the inner surface of the floral tube. Thismia selangorensis is provisionally classified as Critically Endangered according to the IUCN Red List categories and criteria.

Key words: Ecopark, endemic, Geomitra, mitre, achlorophyllous plant, Southeast Asian flora, taxonomy

Thismia selangorensis.
 A. Plants with flowers and roots; B. Top view of mitre (inner tepals); C. Side view of inner tepal; D. Ovary, stigma, and style; E. Floral tube with mitre removed and minute triangular outer tepal; F. Longitudinal section of floral tube with three stamens; G. Outer view of three pendulous stamens; H, I. View of inner side of floral tube, upper part (H), lower part (I); J. Bract; K. Leaf. Drawn by Mohammad Aidil Nordin from the spirit material (FRI 79179 & 79180).

Thismia selangorensis.
A. A plant with full flower and coralliform roots; A1. Claviform tip of mitre appendage; B. Outer tepal and filaments; C. Inner tepal forming a mitre; D. Floral tube and mitre; E. Mitre viewed from above; F. Floral tube with ovary and flower bud surrounded by bracts and tepals split on apex; G. Longitudinal section of floral tube, showing inner part (H); H. Inner surface of floral tube; I. Top view of stamens; J. Inner view of a stamen; K. Outer view of a stamen; L. Six stamens viewed from below; M. Stigma. Photos by Siti-Munirah MY and Mohd Faizal; all from FRI 79179 & 79180; images not to scale (see dimensions in description and Fig. 2).

Thismia selangorensis in its natural habitat.
A. Young flower that is not yet fully developed (uncollected plant); B. Mature flower living just beside the roots of a tree buttress (uncollected plant); C. A clump of T. selangorensis at different stages in its natural habitat (FRI 79182); D. A clump of flowers showing a different stage of mitre (FRI 79179 & FRI 79180). Photos by Gim Siew (A–C) and Mohd Faizal (D).

 Thismia selangorensis Siti-Munirah & Gim Siew, sp. nov.
 
Diagnosis. Thismia selangorensis differs from other species of Thismia sect. Geomitra in the following combinations of characteristics: the flower is white to brownish with peach colouration; the distal part of inner tepals is arrow-like with distinct basal lobes, perfectly connate to each other when young, partly splitting on the sutures with age; mitre is wide and resembling a large umbrella, convex and trilobed when viewed from above in younger flowers, flat and irregularly hexalobed in old flowers.


 Mat Yunoh Siti-Munirah, Tan Gim Siew, Mohd Faizal Mat-Tahir and Ahmad Azhar. 2025. Thismia selangorensis (Thismiaceae): A New mitriform Fairy Lantern Species from Selangor, Malaysia.  PhytoKeys. 267: 9-21. DOI: doi.org/10.3897/phytokeys.267.157968 [28 Nov 2025]