Thismia malayana Siti-Munirah, Hardy-Adrian, Mohamad-Shafiq & Irwan-Syah

Siti-Munirah, Mat Yunoh, Hardy-Adrian, Chin, Mohamad-Shafiq, Sharipudin, Irwan-Syah, Zainuddin & Hamidi, Abd Halim, 2024, Thismia malayana (Thismiaceae), a new mycoheterotrophic species from Peninsular Malaysia, PhytoKeys 242, pp. 229-239 : 229-239

Thismia malayana Siti-Munirah, Hardy-Adrian, Mohamad-Shafiq & Irwan-Syah sp. nov.

Figs 1 , 2 , 3

Diagnosis.

Thismia malayana resembles T. chrysops but differs by the brown-whitish colour of the floral tube (vs. very dark sepia brown), glabrous surface of the tepal appendages (vs. finely ciliate), presence of transverse bars at inner surface of floral tube (vs. bars absent), supraconnective apex of each stamen with 5 appendages: one pair of club-shaped inwards-pointing, one pair of acute outwards-pointing, and one central appendage (vs. 7 appendages: one pair of club-shaped, one pair of acute and 3 central appendages).

Type.

Malaysia. Peninsular Malaysia: Negeri Sembilan, Kuala Pilah Distr., Gunung Angsi FR, Ulu Bendul RP, a trail to Gunung Angsi ., elevation ca. 206–208 m a. s. l., 9 February 2023. Siti-Munirah FRI 101705 (holotype KEP!, spirit collection, barcode no. SC 12021 ]) .

Description.

Achlorophyllous herb, up to 10 cm tall, predominantly glabrous. Roots vermiform, unbranched, ca. 1 mm in diameter, light brown. Stem erect, up to ca. 6 cm long, 0.2 cm in diameter, pale brownish, bearing 1–4 flowers. Leaves 2–4, alternate, distant, triangular to narrowly triangular, scale-like, apex acute, margin slightly irregularly serrate (almost entire), 6 mm long, ca. 1 mm wide at base, pale brown. Involucral bracts 3, spirally / alternately arranged, similar to leaves but slightly larger, triangular to narrowly triangular, scale-like, apex acute, margin entire, 8 mm long, ca. 1.5–2.5 mm wide at base, pale brown or pale orange. Pedicel ca. 2 mm long at anthesis, elongating to ca. 5 cm long after anthesis, pale brown. Flowers terminal, asymmetrical, slightly zygomorphic, ca. 13 mm long (including ovary). Floral tube urceolate-curved, ca. 7 mm long, ca. 5 mm wide at middle, ca. 4 mm wide at base, sigmoidally bent in lower part; outer surface brown to whitish-sepia (whitish proximally & brown distally), with 12 longitudinal ribs orangish proximally & dark brown distally; inner surface reticulate, with whitish transverse bars, of similar color as outer surface. Tepals 6, free, triangular to ovate, apex acute, up to ca. 2.5 mm long, ca. 1.5–2.6 mm wide at base, dark brown, apically bearing a tentacle-like appendage; appendage narrowing towards apex, each equal in length up to ca. 6 mm long, 0.5 mm wide, whitish towards apex, becoming brownish with age. Annulus moderately raised, ring-shaped, ca. 5.4 mm in diameter, with ring width ca. 1.2 mm, orange, becoming bright yellow with age, aperture ca. 3.2 mm in diameter. Stamens 6, pendent from annulus; filaments free, ca. 1 mm long, curved downwards, yellowish to whitish; anther ca. 0.7 mm long; connectives and supraconnectives narrow at base (ca. 1.5 mm wide) and broad at apex (ca. 2 mm wide), with outer side bluish to violet; inner side bluish, violet, whitish to yellowish, flattened at inner surface, laterally connate to form a tube, ca. 4.5 mm long, supraconnective apex with one pair of club-shaped inwards-pointing, ca. 0.8–1 mm long and one pair of acute outwards-pointing ca. 0.3 mm long appendages, and one central appendage ca. 0.5–0.6 mm long; supraconnective bearing a skirt-like lateral appendage at outer side protruding towards inner side of floral tube, bearing trichomes at both sides; lateral appendage not exceeding the tip of the supraconnective appendages, margin lobed with translucent trichomes; interstaminal glands inserted on the line of fusion between supraconnectives at the level of attachment of lateral appendages, bluish (concolorous with supraconnectives). Ovary inferior, unilocular; placentas 3, free, column-like, arising from the bottom of the ovary; ovules numerous. Style ca. 0.74 mm long, dark blackish; stigma ca. 0.85 mm long, papillose, 3 - lobed, with lobes ± rectangular and bifurcate at apex, dark blackish. Fruit dehiscent, cup-shaped, 6 mm in height, 6–8 mm in diameter, pale white to creamy. Seeds long oval, ca. 0.38–0.41 mm long, ca. 0.15–0.17 mm wide.

Additional specimens examined.

Malaysia. Peninsular Malaysia: Negeri Sembilan, Kuala Pilah District, Gunung Angsi FR, Ulu Bendul RP , elev. ca. 206–208 m, February 2023, Siti-Munirah, FRI 101701 ( KEP), FRI 101702 ( KEP), FRI 101703 ( KEP), FRI 101704 ( KEP) FRI 101709 ( KEP), FRI 101710 ( KEP), FRI 101711 ( KEP) ; Pahang, Temerloh District, Tengku Hassanal WR , elev. ca. 200 m, 31 December 2020, Mohamad-Shafiq & Irwan-Syah, FRI 91126 ( KEP) .

Distribution.

Endemic to Peninsular Malaysia. Recorded in two localities: one in Gunung Angsi FR in Negeri Sembilan state and another in Tengku Hassanal WR in Pahang state (Fig. 4 ).

Ecology.

In medium-moist or mesic, shady areas of lowland dipterocarp forests at elevations of 200–450 m a. s. l. Flowering and fruiting usually from December to February but flowering also observed in June. According to the third and fourth author’s observations, T. malayana was only sighted and observed a few times a year, especially during the rainy season.

Etymology.

The specific epithet malayana is derived from Malaya, a name formerly used for Peninsular Malaysia. The epithet refers to the known region of the species distribution.

Conservation status.

According to the IUCN standards ( IUCN 2022), we propose to classify the preliminary conservation status of Thismia malayana as VU (Vulnerable). This particular species has only been found in two locations. One of the sites is located in a protected area (Tengku Hassanal WR), the other in a water catchment forest under the PRF class protection forest (Gunung Angsi FR), which also includes Ulu Bendul RP. Both habitats are therefore considered stable. However, the population of this species was detected near a hiking trail at both sites, which exposes this species to the risk of trampling due to its small size. During the survey conducted between 2022 and 2023, only less than 10 individuals were found. However, due to the limited time and area of the survey and also mycoheterotrophic nature of the species which remains hidden in the soil for most of its life, it was not possible to determine the estimated number of mature individuals in the population. Therefore, this species is classified as Vulnerable based on criterion D 2.

Notes.

According to the classifications of Jonker (1938) and Kumar et al. (2017), T. malayana is placed in subgenus Thismia section Thismia subsection Odoardoa Schltr. ( Schlechter 1921), as it has six free, equal tepals and vermiform roots. Among the Thismia subsection Odoardoa, the following species share the curved or bent floral tube characteristic of T. malayana : T. chrysops from Johor (Gunung Ledang, Peninsular Malaysia) ( Ridley 1895), T. cornuta from Sarawak ( Malaysia) ( Hroneš et al. 2018), T. inconspicua from Brunei ( Sochor et al. 2017) and T. kinabaluensis from Sabah ( Malaysia) ( Nishioka et al. 2018). A detailed morphological comparison of T. malayana and these morphologically most similar four species is presented in Table 1 .

Figures

Figure 1. Thismia malayana A flowering plant B flower, side view C flower, view from above D flower, longitudinal section E three stamens, outer view F tepal with terminal appendage, adaxial view G ovary, longitudinal section H style and stigma I involucral bract, adaxial view J leaf, adaxial view. All drawn by Mohamad Aidil Noordin from spirit material, Siti-Munirah FRI 101705 (A – C); FRI 101701 (D – J).

Figure 2. Thismia malayana A flowering plant A 1 floral tube, inner surface A 2 annulus and stamen filaments, view from inside B inflorescence with anthetic flower and several young fruits B 1 style and stigma B 2 annulus, top view C flower, side view D, E stamens, view from inside and from outside, E 1 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, H 1 fruit after dehiscence, top view, H 2 seeds I shoot base with roots. Photos by Siti-Munirah (A 1 – I) and Hardy-Adrian (A) from FRI 101701 (A), FRI 101702 (F, G, I), FRI 101703 (E 1), FRI 101705 (B, B 2, H, H 1, H 2) & FRI 101710 (A 1, A 2, B 1, C, D, E). Images not to scale (see dimensions in description and Figs 1, 3).

Figure 3. 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 Hardy-Adrian from uncollected plants.

Figure 4. Habitat (in situ) of Thismia malayana in Ulu Bendul RP in Gunung Angsi FR (A, B) and the Tengku Hassanal WR (C – E) A Thismia malayana at its habitat, which is located right next to the main trail to Gunung Angsi B Siti-Munirah showing the habitat of T. malayana C path to Lata Bujang and Gunung Benom D the plants growing on rotten wood E Mohamad-Shafiq observed a Thismia malayana in its habitat. Photos by Siti-Munirah (A, B) and Mohamad-Shafiq (C – E).