Thismia belumensis Siti-Munirah & Suhaimi-Miloko, 2021

Siti-Munirah, Mat Yunoh, Suhaimi-Miloko, Zainol & Ahmad, Mohammad Ismail Zubir, 2021, Thismia belumensis (Thismiaceae), a remarkable new species from The Royal Belum State Park, Gerik, Perak, Peninsular Malaysia, PhytoKeys 172, pp. 121-134 : 121

Thismia belumensis Siti-Munirah & Suhaimi-Miloko sp. nov. Figs 1 , 2 , 3

Diagnosis.

Most similar to Thismia labiata J.J.Sm. but differing in the floral tube partially covered by a massively expanded cucullate bilabiate annulus, longer outer tepals appendage, obovate to spathulate rather than linear to filiform inner tepals and the supraconnective apex curved outwards like a skirt rather than straight.

Type.

Malaysia. Peninsular Malaysia: Perak, Gerik Distr., Royal Belum State Park, ca. 290 m alt., 22 October 2019, M.Y. Siti-Munirah FRI 94758 (holotype: KEP!, spirit collection, No. barcode 279998).

Description.

Terrestrial, achlorophyllous, brownish-whitish-green herbs up to 8 cm tall. Roots vermiform white-brownish. Stems erect (sometimes ascending), unbranched, 2-4 cm long, glabrous. Leaves scale-like, simple, translucent white, 5 mm long, 1-2 mm wide, triangular, apex acute or acuminate, base appressed. Involucral bracts 3, white, up to ca. 1 cm long, lanceolate, apex acute to acuminate, margin entire, glabrous, base appressed. Pedicel 2-4 mm long (post anthesis). Flowers terminal, zygomorphic, solitary, 5-8 cm long (including appendages); floral tube (hypanthium) 5-7 mm long, 3-6 mm wide, narrowed just above the ovary ca. 3 mm wide, widest on upper part ca. 6 mm wide, slightly shorter at one side (lower on the floral aperture side), outer surface verrucose covered with very short minute warts (papillae); basal half green, apical half with 12 dark brown and 12 pale brown (almost translucent) vertical stripes; inner surface smooth without transverse bars and other ornamentation; emerald green and translucent; outer tepals 3, pale brown each 3 × 2 mm, apex acute, each with forming a distal filiform, tentacle-like appendage, the two on the opposite side of the annulus opening erect and the one below the thickened annulus slender, ca. 1.5-2.5 cm long, ca. 1 mm wide, cylindrical, brownish-greenish and sometimes whitish towards the subulate tip; inner tepals 3, brownish to pure white, glabrous (smooth), obovate to spathulate, tightly adpressed and almost completely overlapping the cucullate part of annulus, basally with long and erect appendages, ca. 3 cm long, brownish-greenish and sometimes whitish towards clavate tip. Annulus expanded and modified into a cucullate (hood-like) structure and thickened part of the annulus, the cucullate covering the apical part of the floral tube and forming a downwards floral aperture and facing thickened part of the annulus on one side of the flower; cucullate outer surface white with 3 black lines, glabrous; cucullate inner surface white to brownish-peach, covered with numerous white translucent trichomes pointing inwards. Stamens 6, pendent from the apical part of the floral tube; each connective ca. 3.3 mm long, peach; outer surface with two linear to filiform thecae, each 1.8 mm long, facing the inner wall of the floral tube; inner surface smooth; supraconnective apex blunt and rounded, curved (like a skirt) outwards, covered with transparent trichomes on margin (apparent only in the living state); lateral appendage, apical appendages and interstaminal glands absent; filaments short, connected to floral tube and annulus. Ovary inferior, unilocular, cup-shaped, ca. 3 mm × 4.7 mm, whitish brown outer surface covered with numerous warts; placentas 3, bearing numerous ovules; style ca. 0.4 mm long; stigma triangular-pyramidal, dark greenish, ca. 1.55 mm long, papillate, unusual whitish thickened part on each surface (sometimes difficult to see), apex truncate (trilobed). Fruit cup-shaped, white or pale brown with white operculum, pedicel not elongated.

Distribution.

Endemic to Perak, Peninsular Malaysia. Currently known only from the type locality (Map 1 ).

Ecology.

Lowland dipterocarp forest, under shade, 260-290 m altitude. Flowering from June to October. Thismia belumensis was found growing within tree leaf litter and between the buttress roots of large trees (Fig. 4 ). Two other Thismia species were also discovered within a radius of about 350 meters, T. javanica and Thismia sp. 1 (see Fig. 5 ), which is currently suspected by the authors to be Thismia arachnites Ridl., but further examination is still needed. All plants were found close to the walking trail.

Etymology.

The species is named after The Royal Belum State Park, the type locality of this species.

Conservation status.

Critically Endangered (B1B2ab(iii)). Following the IUCN Standards and Petitions Committee (2019), this species is assessed as critically endangered as it is only known from the type locality and is certainly endemic and rare. Fewer than ten specimens were observed, including flowering and fruiting individuals. Although the locality is within the State Park forest reserve, a protected area, the area is located beside the walking trail, which is a common visiting site for tourists in the Park. The site where T. belumensis was found is currently designated as a Tourist Zone in the Royal Belum State Park Management Plan 2018-2027. All guides can freely bring tourists to the area without special permission from the Perak State Park Corporation. Due to the small size of T. belumensis , it may not be noticed, and so has a high chance of being stepped on. Without official reminders or guidance, the existence of T. belumensis might be threatened by ecotourism activities. Thismia belumensis qualifies for CR (B1B2ab(iii)) for its single location, EOO less than 100 km2, and AOO less than 10 km2. Its habitat quality is also threatened by wild boars (personal observation by Suhaimi-Miloko) and other destructive activities, such as regular visits by tourists to the area. Together, these have the potential to cause a population reduction.

Additional specimen examined.

Peninsular Malaysia. Perak: Gerik, Royal Belum State Park, ca. 260 m alt., 22 October 2019, M.Y. Siti-Munirah FRI94752 (KEP, spirit collection, No. barcode 279997).

Figures

Figure 1. Illustration of Thismia belumensis Siti-Munirah & Suhaimi-Miloko A habit B side view of flower C back view of flower D longitudinal section of the floral tube showing pendulous stamen with ovary and stigma E outer view of stamens F inner view of stamens G outer tepal H inner tepal I longitudinal section of hood (annulus) and pendulous stamens J longitudinal section of ovary K stigma L pistil M ovules N bract O leaf. All from FRI 94752 & FRI 94758, drawn by Mohamad Aidil Noordin.

Map 1. Map of Peninsular Malaysia indicating the location of Thismia belumensis (●).

Figure 2. Outer appearance of Thismia belumensis Siti-Munirah & Suhaimi-Miloko A root and stem B flower from side view C flower showing the erect tepal appendages of the live plant D tip of erect tepal appendages E slender appendage of outer tepal F side view showing inner tepals overlaying the cucullate structure G floral tube with the floral aperture of the expanded annulus H outer tepals alternate with inner tepals, each with distal or dorsal appendage I top view of flower showing inner tepals overlapping on cucullate structure J semi-round shape of the aperture of the annulus (All photos by Siti-Munirah MY, FRI 94752 & FRI 94758).

Figure 3. Inner flower appearance of Thismia belumensis Siti-Munirah & Suhaimi-Miloko K longitudinal section showing the internal parts of flower L longitudinal section of floral tube and apical part (L 1 left side L 2 right side) showing pendulous stamen attached to the filament, expanded annulus developing a cucullate (hood-like) structure, thickened part of the annulus at one-side, and outer surface of hood overlaid by inner tepals M transverse section of floral tube at lower part showing the apex of fused pendulous stamen and the floral aperture with the thickened part of the annulus in the centre N inner view of stamens and filament attached to the expanded annulus, which is covered with white trichome hairs O inner view of two stamens and hood inner surface P stamen (from inner view) Q stamen displaying linear to filiform thecae (outer view) and supraconnective apex curved outwards R top view of ovary and stigma S stigma from side view (S 1 shows triangular-pyramidal S 2 shows whitish part on surface) T cross-section of ovary showing young seeds (All photos by Siti-Munirah MY, FRI 94752 & FRI 94758).

Figure 4. Thismia belumensis Siti-Munirah & Suhaimi-Miloko A habitat B T. belumensis growing in leaf litter, FRI 94758 C habit of the young flowering plant and the young fruit of T. belumensis D fruits of T. belumensis, in-situ (Photos by A-C Siti-Munirah MY D Suhaimi-Miloko Z).

Figure 5. Other Thismia species found in the same area as T. belumensis A Thismia sp. 1, undescribed species B top view of Thismia sp 1. showing the annulus and tepals C Thismia javanica D top view of T. javanica showing the annulus and tepals (symmetrical flower) (All photos by Siti-Munirah MY).