Thismia kenyirensis Siti-Munirah & Dome, 2023

Siti-Munirah, Mat Yunoh & Dome, Nikong, 2023, Thismia kenyirensis (Thismiaceae), a new species from Taman Negeri Kenyir, Terengganu, Peninsular Malaysia, PhytoKeys 221, pp. 61-72 : 61

Thismia kenyirensis Siti-Munirah & Dome sp. nov.

Figs 1 , 2 , 3

Diagnosis.

Distantly similar to Thismia hongkongensis Mar & Saunders but differs by petaloid, ovate outer tepals which are ca. 8 mm long, narrowly lanceolate-linear, ca. 8 mm long inner tepals which are not forming a lose-dome, up to 28 mm long appendages of inner tepals, orange floral tube, which lacks reticulate pattern on its inner surface and connective apex with 3 long appendages.

Type.

Malaysia. Peninsular Malaysia: Terengganu, Hulu Terengganu District, Taman Negeri Kenyir, Sungai Cendana , elev. ca 204 m, 8 Sept 2020, Dome Nikong, FRI 91122 a (holotype KEP!, spirit collection, barcode no. SC12015) .

Description.

Achlorophyllous herb, up to 130 mm tall. Roots vermiform, unbranched, ca. 1 mm in diameter, light brown. Stem erect, up to 90 mm long, 1.5-2 mm in diameter, pale brownish-orange, bearing 1-2 flowers. Leaves 2-4, spirally arranged, triangular to narrowly triangular, scale-like, acute, margin almost entire but slightly irregularly serrate, 2-6 mm long, ca. 1 mm wide at base, pale brown. Involucral bracts 3, similar to leaves but slightly larger, spirally arranged, triangular to narrowly triangular, scale-like, acute, entire, 8 mm long, ca. 1.5-2.5 mm wide at base, pale brown or pale orange. Pedicel up to 6 mm long at anthesis, elongating to ca. 10 mm long after anthesis, pale brown. Flowers terminal, actinomorphic, ca. 52 mm long (including ovary, floral tube and inner tepal with appendage); floral tube urceolate, 12-15 mm long, ca. 5 mm wide at base, ca. 6 mm wide at middle, ca. 7 mm wide distally; outer surface glabrous, orange to brownish-orange, with 12 darker orange longitudinal ribs alternating with 12 paler longitudinal lines, inner surface smooth or rough, almost similar to outer surface, without transverse bars or reticulate ornamentation; outer tepals 3, free, petaloid, ovate, apex acute, 8 mm long, ca. 4-5.5 mm wide (ca. 4 mm at base, ca. 5.5 mm above middle), glabrous, bright orange; inner tepals 3, free, narrowly lanceolate-linear, 8 mm long, ca. 1 mm wide, glabrous, dark orange, apically bearing a tentacle-like appendage; appendage narrowing towards apex, ca. 27-28 mm long, 0.5 mm wide, dark orange at base and bright orange at apex; annulus dark orange, glabrous. Stamens 6, pendent from the annulus, outer side greenish-orange or greenish-brown, inner side dark-brown to blackish and paler, filaments free, ca. 1 mm long, curved downwards; connectives flattened at inner surface, laterally connate to form a tube, ca. 4-5 mm long, narrow at base (ca. 0.8 mm wide) and broad at apex (ca. 1.7 mm wide), connective apex with 3 appendages, slightly curved inside, each appendage ca. 1.5 mm long; outer side of connective bearing a skirt-like lateral appendage protruding towards floral tube; lateral appendage not exceeding the tip of the connective appendages, with short translucent trichomes on margin, interstaminal glands greenish translucent, inserted on the line of fusion between connectives at the level of attachment of lateral appendages. Ovary inferior, unilocular; placentas 3, free, forming columns and arising from the bottom of the ovary; ovules numerous. Style dark brown-orangish, ca. 1 mm long; stigma ca. 1 mm long, papillose, 3-lobed, with lobes ± rectangular, bifurcate at apex, pale brown or orangish to whitish. Fruit cup-shaped, 3-5 mm in height, 4-6 in diameter, pale orange (or white to creamy orange), darker at upper part. Seeds unknown.

Additional specimen examined (paratype).

Malaysia. Peninsular Malaysia: Terengganu, Hulu Terengganu District, Taman Negeri Kenyir, Sungai Cendana, elev. ca 204 m, 8 Sept 2020, Dome Nikong, FRI 91122b (KEP, spirit collection, barcode no. SC12016), FRI 91122c (KEP, spirit collection, barcode no. SC12017); Taman Negeri Kenyir, Sungai Cendana, elev. ca. 156 m, 16 June 2022, Siti-Munirah MY, FRI98678 (KEP, spirit collection, barcode no. SC12018).

Distribution.

Endemic to Terengganu, Peninsular Malaysia. Currently, the occurrence is only from the type locality, Sungai Cendana area (Map 1 ). In addition, T. kenyirensis was observed in two other populations in the vicinity of Tasik Kenyir. It was sighted near Sungai Saok and on the way to Gunung Gagau (Wong Pui May personal communication), both in the Tasik Kenyir region. However, there are still no specimens and GPS information to verify these findings. This means that only the occurrence of the population in Sungai Cendana has been confirmed.

Ecology.

In moist shady areas of lowland dipterocarp forest on moist soil at elevations of 150-220 m a.s.l. Flowering and fruiting mostly from September to April, but also recorded to flower in June. Historically, the type locality was botanized as early as 2007. Based on the results of Lim et al. (2008), T. alba was also recorded during the survey in the Sungai Cendana area. This is in contrast to T. kenyirensis , which was not mentioned, implying that it was not seen or collected at that time. During our recent visit, we were also able to find T. alba not far from the original population of T. kenyirensis .

Etymology.

The epithet refers to Lake Kenyir, Kenyir State Park (Taman Negeri Kenyir), where the species was found.

Conservation status.

According to the IUCN standards ( IUCN 2022), we propose to classify the preliminary conservation status of the species as Least Concern (LC). This is because the species is likely to be widespread in TNK, where it has been sighted a few times at the type locality (Sungai Cendana) and also by other observers at two other sites, and its entire habitat is in a fully protected forest area. In addition, nearby forests in Terengganu National Park (Taman Negara Terengganu) are also fully protected. As mentioned earlier, it is very likely that there are other populations in the vicinity of Tasik Kenyir. According to the second author’s observations, four individuals were sighted near Sungai Saok and one on the way to Gunung Gagau on 22 November 2022. However, no specimens are available for confirmation. Thismia kenyirensis occurs in intact habitats in forested areas in TNK. However, the species is very common only during the flowering season and its populations are mostly scattered, as few individuals or solitary individuals were observed during the flowering season. During the first check of the type locality, the population in Sungai Cendana in 2020, about 20 adult individuals were found. However, during a revisit in 2022, only a single individual was observed.

Notes.

Thismia kenyirensis is easily recognised by the following combination of characteristics: vermiform roots, almost uniform light-to-dark orange flower coloration, petaloid ovate outer tepals, narrowly lanceolate-linear inner tepals with long appendages and each stamen with 3 appendages at its apex. Within the infrageneric classification by Kumar et al. (2017), T. kenyirensis resembles species of Thismia subgenus Thismia section Thismia subsection Brunonithismia Jonker, especially by its free and unequal tepals. Eight species are placed in subsection Brunonithismia by Kumar et al. (2017): T. arachnites , T. brunonis Griff, T. gardneriana Hook.f. ex Thwaites, T. hongkongensis , T. javanica , T. labiata J.J.Sm., T. neptunis Becc. (proved to be only distantly related to the other species of the subsection by Shepeleva et al. 2020) and T. tentaculata K.Larsen & Aver. Of them, T. arachnites and T. javanica occur in Peninsular Malaysia, including the state of Terengganu. They both are readily distinguished from T. kenyirensis (Fig. 4 , Table 1 ). In addition, T. breviappendiculata Nob. Tanaka ( Tanaka et al. 2018) from Myanmar, T. bokorensis Suetsugu & Tsukaya ( Suetsugu et al. 2018) from Cambodia, T. gardneriana from Sri Lanka and T. tentaculata from Hong Kong and Vietnam are similar to T. kenyirensis . In a molecular phylogenetic reconstruction provided by Shepeleva et al. (2020), T. javanica , T. hongkongensis , T. gardneriana and T. tentaculata occupied a relatively isolated and unstable position. All these species (and also T. kenyirensis ) are characterised by free appendaged inner tepals and outer tepals without appendages. A more detailed phylogenetic analysis is required to test the monophyly of this morphological group, and the relationships of each of these species including T. kenyirensis .

Figures

Figure 1. Thismia kenyirensis A plant with flower and roots B top view of flower showing tepals C top view of ovary and stigma D stamen (i, side view; ii, inner view) E outer view of three pendulous stamens F longitudinal section of ovary G style and stigma H bract I leaf. All from FRI 91122 a (spirit material). Drawings by Mohamad Aidil Noordin.

Map 1. Taman Negeri Kenyir, Terengganu (black circle), the type locality of Thismia kenyirensis.

Figure 2. Thismia kenyirensis A mature plant with flowers and roots, scale in centimetres (cm) (FRI 91122 b) B mature plant in natural habitat (FRI 91122 a) C vermiform roots (FRI 91122 c) D young flower with mature ovary and stigma (FRI 91122 c). Photos by Siti-Munirah MY (A); Dome Nikong (B-D).

Figure 3. Thismia kenyirensis A bracts with ovary and pistil, lateral view B top view of stigma C flower, side view D longitudinal section of floral tube and stamens E flower, top view F annulus G stamens, outer view. Photos by Siti-Munirah MY (A-C, E, F; All from FRI 91122 b); Dome Nikong (D, G; No specimens).

Figure 4. Morphologically close species to T. kenyirensis in Peninsular Malaysia A-C T. arachnites (Taman Negeri Kenyir) D-F T. javanica (Telemong Forest Reserve). Photos by Dome Nikong (A-C, F) and Siti-Munirah MY (D, E, G).