Friday, February 19, 2021

[Botany • 2021] Thismia belumensis (Thismiaceae) • A Remarkable New Species from The Royal Belum State Park, Gerik, Perak, Peninsular Malaysia

 Thismia belumensis Siti-Munirah & Suhaimi-Miloko

in Siti-Munirah, Suhaimi-Miloko & Ahmad, 2021. 

This report describes Thismia belumensis Siti-Munirah & Suhaimi-Miloko, a novel species of achlorophyllous herb discovered in the Royal Belum State Park, Peninsular Malaysia. This new species is unlike any previously described species of Thismia. In particular, T. belumensis possesses a unique annulus, which has been expanded and modified into a cucullate (hood-like) structure. This structure covers the apical floral tube and has an opening on one side facing a thickened part of the annulus, and the off-centre floral aperture confers a zygomorphic symmetry to the flower, indicating T. belumensis is more similar to Thismia labiata J.J.Sm. This morphological detail makes this new species distinct from all other described species of Thismia. In this report, we provide descriptions, illustrations, colour plates, and the provisional conservation status of Thismia belumensis.

Keywords: Conservation status, endemic, Peninsular Malaysia, Perak, Thismia belumensis, zygomorphic

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 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.

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 (L1 left side L2 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 (S1 shows triangular-pyramidal S2 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).

Thismia belumensis Siti-Munirah & Suhaimi-Miloko, sp. nov.
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.

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.

Mat Yunoh Siti-Munirah, Zainol Suhaimi-Miloko and Mohammad Ismail Zubir Ahmad. 2021. Thismia belumensis (Thismiaceae), A Remarkable New Species from The Royal Belum State Park, Gerik, Perak, Peninsular Malaysia. PhytoKeys. 172: 121-134. DOI: 10.3897/phytokeys.172.59336

Spesies baru untuk Malaysia