Thismia malayana: A new species of Parasitc Plant from Peninsula Malaysia.

Thismias, Thismia spp., are a curious group on Monocotyledonous Plants found in the evergreen forests of tropical and subtropical Asia, northern and eastern Australia to New Zealand, the north-central USA, Costa Rica and southern tropical America. They are Mycoheterotrophs, obtaining nutrition parasitically from the network of Mycorrhizal Fungi which exchange nutrients with the Plants of the forest, but contributing nothing themselves to the relationship. Thismias do not photosynthesize, enabling them to live on the darkest parts of the forest floor, and live most of their lives below ground, occasionally producing intricate, but often inconspicuous, flowers at most a few centimetres high, which are pollinated by Fungus Knats or similar small Insects.

In a paper published in the journal Phytotaxa on 31 May 2024, Mat Yunoh Siti-Munirah of the Forest Research Institute Malaysia, independent researchers Chin Hardy-Adrian, Sharipudin Mohamad-Shafiq, and Zainuddin Irwan-Syah, and Abd Halim Hamidi of the Negeri Sembilan Forestry Department, describe a new species of Thismia from Peninsula Malaysia.

The new species is named Thismia malayana, where 'malayana' is derived from 'Malaya' the old name for Peninsula Malaysia. The species is described from a specimen collected in the Kuala Pilah District of Negeri Sembilan State, Malaysia, on a trail leading to Gunung Angsi mountain, in February 2023.

Thismia malayana (A) flowering plant (A1) floral tube, inner surface (A2) annulus and stamen filaments, view from inside (B) inflorescence with anthetic flower and several young fruits (B1) style and stigma (B2) annulus, top view (C) flower, side view (D), (E) stamens, view from inside and from outside, (E1) stamen supraconnectives: one pair of club-shaped inwards-pointing, one pair of acute outwards-pointing, and one central appendage (F) stamen supraconnectives, apical view (G) stamen tube, view from below (H), (H1) fruit after dehiscence, top view, (H2) seeds I shoot base with roots. Siti-Munirah et al. (2024).

Thismia malayana exists as a vermiform root, light brown, unbranching and about 1 mm in diameter, which produces a light brown herbaceous Plant, reaching a maximum height of about 10 cm. This above-ground Plant comprises a stem about 6 cm long and 0.2 cm in diameter, from which grow 2-4 scale-like brown leaves, and 1-4 asymmetrical, tube-shaped flowers, up to about 7 mm long and 5 mm in width, brown-to-off-white in colour, with orange longitudinal ribs, and an opening surrounded by six triangular tepals. 

Thismia malayana with scales (the finest grade is 0.5 mm) (A) side view (B) top view (C) the size compared to the 20-sen coin (23.59 mm in diameter). Photos by Chin Hardy-Adrian from uncollected plants. Siti-Munirah et al. (2024).

 

Thismia malayana is known from only two localities, one in the Gunung Angsi Forest Reserve in Negeri Sembilan State, and the other in Tengku Hassanal Wildlife Reserve in Pahang State. In both locations it grows in moist, shady areas of Diptocarp forests, at elevations of 200-450 m above sealeavel, usually producing flowers and fruit between December and February (although flowering in June has also been observed). 

Habitat (in situ) of Thismia malayana in Ulu Bendul Recreational Park in Gunung Angsi Forest Reserve (A), (B) and the Tengku Hassanal Wildlife Reserve (C)–(E). (A) Thismia malayana at its habitat, which is located right next to the main trail to Gunung Angsi. (B) Mat Yunoh Siti-Munirah showing the habitat of Thismia malayana. (C) Path to Lata Bujang and Gunung Benom (D) The plants growing on rotten wood (E) Sharipudin Mohamad-Shafiq observing a Thismia malayana in its habitat. Photos by Mat Yunoh Siti-Munirah (A), (B) and Sharipudin Mohamad-Shafiq (C)–(E). Siti-Munirah et al. (2024).

Thismia malayana is known only from two locations, with less than 10 individual Plants observed. Both locations are in protected areas, although on is quite close to a forest trail, where it might be disturbed by visitors. The species is extremely cryptic in nature, making it likely that is exists in other areas and has not been discovered. For these reasons, Siti-Munirah et al. recommend that the species be classified as Vulnerable under the terms of the International Union for the Conservation of Nature's Red List of Threatened Species. 

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