Thismia terengganuensis M.Y.Siti-Munirah, 2019

Yunoh, Siti-Munirah Mat & Nikong, Dome, 2019, Thismia domei and T. terengganuensis (Thismiaceae), two new species, and T. javanica, a new record from Terengganu, Peninsular Malaysia, PhytoKeys 124, pp. 123-137 : 127-129

Thismia terengganuensis M.Y.Siti-Munirah sp. nov. Figure 4 , 5 , 6

Diagnosis.

Thismia terengganuensis is unique in its perfect mitre with the long filiform appendages not seen in any other species of Thismia . It has a racemose sessile inflorescence with large bracts. Its flower parts are brownish with brown striae with inner perianth lobes forming a dark brown mitre with a white slender appendage attached at apex. The outer perianth lobes at interval appear like a wing. It has creeping vermiform brown roots.

Type.

MALAYSIA. Peninsular Malaysia: Terengganu, Kuala Berang District, Hulu Telemong Forest Reserve, ca 227 m alt., 2 Dec 2018, Dome Nikong, FRI 91112 (holotype KEP!).

Description.

Small perennial achlorophyllous herbs. Roots creeping, vermiform, brown. Stem white, 3-3.5 cm long, ascending, glabrous. Leaves scale-like, triangular, ca. 3 mm long, apex acute, alternate. Bracts many, large, 1-1.5 cm long, crowded. Pedicel short or up to 3-4 cm long. Inflorescence racemose. Flowers sessile, perianth tube urceolate, ca. 1 cm long, 5 mm wide in the upper third, brownish-white, with inconspicuous brown longitudinal stripes from upper part to the base. Apex of perianth tube covered with the dark brown apical part of perianth tube, circular, slightly raised annulus with opening aperture ca. 2 mm in diameter. Perianth lobes divided into 2 types; inner perianth lobes 3, erect, convergent to connate at apex, forming a mitre, dark brown, each with long and slender filiform appendages, 5-7 cm long; outer perianth lobes 3, recurved, all equal in shape and size, long triangular, boat-like, 4-5 mm long, 2 mm wide at base, white, tapering into curved apex. Stamens 6, brownish white; filaments short, free, attached to the mouth of the perianth tube, curved downwards; connectives blunt (tongue-like), without apical appendages; thecae yellow, not connected; lateral appendage skirt-like. Ovary white, cup-shaped, inferior, free central placentation; style short; stigma 3-lobed, papillose. Fruit cup-shaped, brownish.

Distribution.

Endemic in Peninsular Malaysia, Terengganu. Currently only known from the type locality.

Ecology.

In lowland dipterocarp forest on wet, moist soil in shade at altitude 227 m. Flowering in November-December on forest floor under canopy of dense shrubs.

Etymology.

The epithet refers to the state, Terengganu, where it was found.

Conservation status.

Critically Endangered (B2 ab(iii)). Following the 2012 IUCN Red List Categories and Criteria, (IUCN 2012), this species is assessed as critically endangered because it is only known from one locality where less than 5 individuals flowering and fruiting individuals were observed. Thismia terengganuensis is currently known only from the type locality and is certainly a very rare species. The locality is within the forest reserve but is threatened by selective logging activities within the forest reserve that are currently ongoing.

Notes.

Thismia terengganuensis is most similar to species in sect. Sarcosiphon and sect. Geomitra in the shape of the perianth tube and mitre but differs in all other morphological parts, e.g. in its slender filiform appendages on the apex of mitre and also its connectives that are blunt without any apical appendages.

Figures

Figure 4. Thismia terengganuensis Siti-Munirah A habit of flowering and fruiting plants B top view of plant C root and stems D perianth tube E perianth lobes (inner forming a mitre, outer curved) F ovary with pistil (stigma) G fruits with seeds H stamens attached to the inner wall of mouth of the perianth tube (adaxial view) I stamens deflexed (abaxial view). Photo credit: A-D, G Dome Nikong; E, F, H, I Siti-Munirah MY.

Figure 5. Thismia terengganuensis Siti-Munirah A flower and fruit B habit of fruiting plant C leaf D bracts E stamens (adaxial view) F stamens (abaxial view) G ovary showing free central placentation H stigma. All from Dome Nikong FRI 91112. Drawn by M. Aidil.

Figure 6. Thismia terengganuensis A habitat B habit of a fading T. terengganuensis plant. Photo credit: Dome Nikong.