Thismia perlisensis Besi & Rusea, 2024

Besi, Edward Entalai, Jabar, Qistina Anis Mad, Rahman, Syamil Abd, Saad, Mohd Zulkifly, Ahmadni, Ag Shaffie Ag & Go, Rusea, 2024, Thismia perlisensis (Thismiaceae), a new red-annulus Thismia species from Peninsular Malaysia, Phytotaxa 675 (1), pp. 1-10 : 2-7

Thismia perlisensis Besi & Rusea sp. nov. ( Figs. 1 & 2 ).

Type: — MALAYSIA. Peninsular Malaysia: Perlis State, Perlis State Park, ca. 100 m elev., 4 October 2022, E. E. Besi, M. I. Mat Esa, S. H. Tan, D. Sandin & R. Go EDW136 (holotype UPM spirit collection).

Diagnosis: — Thismia perlisensis can be easily distinguished from the Thismia arachnites Ridley (1905: 197) and Thismia javanica J.J.Sm. (1910: 32) by the blood-red, dome-shaped annulus (vs. ring-like with rim, orange annulus), prominent trilobed stigma with 1.8 mm long, bifid and subulate lobes (vs. ovate, truncate stigma), and claviform apices of appendages of the inner tepals (vs. subulate apices of appendages of the inner tepals).

Description:—Herb achlorophyllous, s mall, terrestrial, ca. 5 cm tall. Roots clustered, horizontal, vermiform, fleshy, light brown tinged with white. Stem 1 cm long, erect-ascending, unbranched, 1–1.5 mm in diameter, white, glabrous. Leaves 4, white, appressed, clasping stem, narrowly triangular with acute apex, scale-like, 3–6 mm long, 0.9–2 mm wide; basal leaves smallest, upper leaves (almost equivalent to floral bracts) largest. Floral bracts oblong-triangular, entire, acute, ca. 1 cm long, 2 mm wide, pale brown. Pedicel 2–3 mm long, white. Inflorescence flowers solitary, actinomorphic, of six fused tepals, forming a floral tube with free apical tepals, ca. 3.5 cm long to the tip of the inner tepal appendage; white to dark red; floral tube (hypanthium) urceolate, ca. 1.2 cm in height, ca. 8.4 mm in width in the upper part, translucent; apex of floral tube fused to form a bright red, glossy, convex annulus, 0.8–1.0 mm wide, longitudinally grooved with 7 vertical ribs, reddish at upper part; outer surface white with ca. 12 vertical reddish streaks on the upper half of the ribs, verrucose, ribbed; inner surface reticulate, transverse bars present; outer tepals 3, ovate, apex obtuse to rounded, tongue-like, hangs down over the upper margin of the perianth tube, 2.3 mm long, 2 mm wide at base, white; inner tepals 3, erect, narrowly triangular, apices obtuse, ca. 3 mm long, ca. 0.9 mm wide at base, tapering from the proximal lower margin into a long, reddish to reddish white filiform appendages, ca. 2 cm long, ca. 0.4 mm in diameter, apices claviform, 3 mm long, 0.5 mm in diameter; annulus (apical part of the floral tube) blood red, rounded, ca. 7 mm wide, convex, raised ca. 2 mm in height, dome-shaped, without rim, connected with the inner tepals; upper surface glossy; aperture, ca. 1.2 mm in diameter, hexagonal; lower margin minutely rugose; stamens 6, reddish, pendent from the annulus, 3 mm long, 2.8 mm in diameter, individual stamen with 2 thecae, thecae ca. 0.8 mm long and 0.5 mm wide; filaments 6, reddish, 0.5–0.8 mm long with apertures 0.2 mm wide in between filaments; supraconnectives 6, ca. 2.6 mm long, laterally connate, forming a tube, glabrous on the outer surface, apices tridentate with an indistinct and fragile hair on the free margins, with a triangular to quadrangular lateral appendages, upcurved; interstaminal glands, rounded, on the line of fusion between each connective; pistil ca. 2–2.3 mm long, white; style ca. 0.8 mm long, cylindrical, slender, erect, glabrous; stigma ca. 1–1.5 mm long, up to 1.8 mm long when the lobes straightened, glabrous, 3-lobed; lobes bifid, narrowly triangular or subulate, apices acute, lobes apices curved inward, white; ovary inferior, cup-shaped or obconical, ca. 2 mm long. Fruit not seen.

Distribution: —Stenoendemic to the northern part of Peninsular Malaysia, Perlis State, and it possibly occurs in Langkawi Island ( Fig. 3 ). While there have been sightings of the plant on Langkawi Island, these locations have only been based on photos posted on social media. Currently, there are no specimens or additional information to confirm these locations.

Habitat and ecology: —Growing on a damp sandy soil of a wetland forest, under shade of fan palms, Licuala peltata , Donax canniformis , and Eugeissona tristis at an elevation of about 100 m a.s.l.. Flowering was recorded in October. A fly (Diptera) was observed to be trapped in the floral tube ( Fig. 4 ). The fly must had been trapped inside the flower during the sample collection. This supports the observation made by Guo et al. (2019) who confirmed that Diptera often visit Thismia flower.

Etymology: —The specific epithet is named after Perlis State, the type locality of this species.

Conservation status: — Thismia perlisensis was discovered at its type locality in Perlis State Park, where minimal human activity helps protect its habitat. However, being a holomycoheterotrophic species, its cryptic growth habit and brief flowering period make estimating mature individuals difficult. Nothing much is known about the habitat and ecological preference, population structure of the species. Thus, following the IUCN Red List Categories and Criteria version 14 (August 2019) ( IUCN Standards and Petitions Committee, 2019), T. perlisensis is assessed currently as Data Deficient (DD). More studies and monitoring of this species are highly recommended.

Taxonomic notes: —Following the taxonomic treatment of Jonker (1948), Sect. Thismia Schltr. (Sect Euthismia Schltr.) is classified into two subsections, Subsect. Odoardoa Schltr. with tepals equal in length and size, and Subsect. Brunonithismia Jonker with inner tepals larger than outer ones ( Jonker, 1948). The new species belongs to Thismia Sect Thismia Subsect. Brunonithismia (Type: T. brunonis Griff. ). In addition, following the identification key of the subgenera, sections, and subsections of Thismia in Kumar et al. (2017), T. perlisensis is falling within the Subgen. Thismia Sect. Brunonithismia by having anther thecae free, mitre absent, and free tepals distinctly dissimilar in shape and size. In the Subsect. Brunonithismia, the gross morphology of T. perlisensis is similar to that of several other species with actinomorphic flower with ovate outer tepals, such as T. arachnites , T. breviappendiculata Nobuyuki Tanaka (2018: 68) , T. javanica , and T. tentaculata Kai Larsen & Averyanov (2007: 16) . Previously, only T. arachnites and T. javanica were reported occurring in Peninsular Malaysia. Thismia perlisensis is similar to T. javanica , in having the urceolate floral tube, inner wall of floral tube with longitudinal ribs connected by many transverse bars, outer tepals ear-shaped and ovate, inner tepals triangular terminated with filiform tentacles, dentate connective apical margins. However, Thismia perlisensis is easily distinguished by its outer appearance, the prominent reddish dome-shaped annulus with a small aperture, instead of yellowish or orangish annulus with rim (raised margins, ring-like) and a wider (more than 2 mm wide) aperture. The dome-shaped and blood-red annulus in the new species is unique. The raised, dome-shaped, glossy, and blood-red coloured annulus distinguishes T. perlisensis from all its congeners. In addition, aside from the size differences of the vegetative and floral parts, none of these species share bifid and subulate stigmatic lobes as in T. perlisensis ( Table 1). Similar to T. breviappendiculata , an endemic species to Myanmar, T. perlisensis has inner tepals filiform with claviform apex but differs in the total length of the tepals (2 × 0.7 cm), and shape of annulus and stigmas. To date, apart from T. perlisensis and T. breviappendiculata , no other species of Subsect. Brunonithismia bearing tepal appendages with claviform apices has been discovered and reported.

Key to the species of Thismia Subgen. Thismia Sect. Brunonithismia modified from Tsukaya & Okada (2012):

1. Flowers zygomorphic ........................................................................................................................................................... T. labiata Flowers actinomorphic .......................................................................................................................................................................2

2. Inner tepals simple. Tube with prominent horizontal bars inside.......................................................................................................3 Inner tepals consisting of 3 parts. Perianth tube without bars............................................................................................ T. neptunis

3. Stigma (including style) ca. 1-2 mm long, trilobed; lobes ca. 1 mm long, oblong-qudrangular, truncate, finely papillose ..............4 Stigma (including style) ca. 3 mm long, trilobed; lobes ca. 1.8 mm long, bifid, subulate, apices curved inward, glabrous.............5

4. Outer tepals short, ear-shaped ............................................................................................................................................ T. javanica Outer tepals long, petaloid.............................................................................................................................................. T. kenyirensis

5. Annulus with rim, round-hexagonal................................................................................................................................ T. arachnites Annulus dome-shaped, without rim ............................................................................................................................... T. perlisensis ......continued on the next page

Figures

FIGURE 1. Thismia perlisensis in the wild. Images by Edward Entalai Besi and Muhamad Ikhwanuddin Mat Esa.

FIGURE 2. Flower’s dissection of Thismia perlisensis. A. Plant. B. Flower. C. Claviform apex of an inner tepals. D. Dome-shaped annulus. E. Stamens and pistil. F. Stamens. G. Anther thecae. H. View of the supraconnectives. I, J. Pistil with stigmas straightened showing subulate lobes. B–J spirit-preserved specimens. Images by Edward Entalai Besi.

FIGURE 3. Map of Peninsular Malaysia showing locations of Thismia perlisensis (●).

FIGURE 4. Habitat and ecological interactions of Thismia perlisensis, including a floral visitor. A, B, C. The habitat views. D, E, F. A Diptera species trapped within the floral chamber of T. perlisensis. Images by Edward Entalai Besi.