Thismia kinabaluensis T. Nishioka & Suetsugu, 2018

Nishioka, Tatsuki, Suetsugu, Kenji, Repin, Rimi & Kitayama, Kanehiro, 2018, Thismia kinabaluensis (Thismiaceae), a new species from Mt. Kinabalu, Sabah, Borneo, Phytotaxa 360 (2), pp. 174-178 : 174-176

Thismia kinabaluensis T. Nishioka & Suetsugu , sp. nov. ( Fig. 1 )

Type:— Malaysia. Borneo. Sabah: Mt. Kinabalu, Nalumad , N 06°06’20.3” ; E 116°42’49”, ca. 700 m elevation, 11 September 2017, T. Nishioka TN-460, whole plant in spirit (holotype SNP) .

Small, achlorophyllous mycoheterotrophic herb. Roots clustered, vermiform, creeping, branched, whitish brown. Stems erect, horizontal or almost missing, simple, solitary flowered, slightly zygomorphic, less than 1.2 cm (to 2.4 cm when fruiting) long, white. Leaves and bracts lanceolate, reduced, up to 6.5 mm long, apex acute. Flower perianth actinomorphic with 6 tepals fused to form a basal urceolate perianth tube, free apically; perianth tube, ca. 7 mm long, ca. 5 mm diameter, white with 12 thin ribs, apically light brown or beige streaks, leading down from outer surface of each perianth lobe and from joints between the lobes, basally bent or inclined at an angle to the ovary, thus the upper part of the perianth displaced from the ovary axis. Transverse bars throughout the perianth tube inside. Perianth lobes all equal in shape, narrowly triangular, 1.8 mm wide and 2.5 mm long at base, pale blue, tapering into long pale blue filiform appendages 6 mm long. Annulus funnel shaped, orange to yellow. A blue circle on the outer margin of annulus. Filaments 6, flattened, free, short, ribbon-shaped, curved downwards, apically lobed, borne on the thickened margin of the perianth tube; stamens apically connate, forming an anther tube, 2 mm long; individual stamen bearing 2 anthers of 0.3 mm long; lateral appendage of connective box-shaped with a tuft of hairs at each apex. Trough surface of lateral appendage entire, narrow or almost missing; apex of stamen with one filiform appendage of 0.3 mm between two club or globe shaped appendages of 0.4 mm. Style short, stigmas 3, bifid. Fruits cup-shaped, crowned by the basal ring, borne on elongated pedicel up to 4 cm long. Ovary white, cup-shaped, inferior. Seed golden brown, ellipsoid.

Distribution:— The distribution of Thismia kinabaluensis appears to be restricted to one location, in Nalumad, Mt. Kinabalu, Sabah, Borneo.

Habitat:— The known Thismia kinabaluensis population occurs at an elevation of approximately 700 m within a mixed dipterocarp forest on soils derived from serpentine rocks dominated mainly by Shorea laevis Ridley (1922: 232) , Agathis borneensis Warburg (1900: 184) , Dacryodes costata (Bennett 1875: 537) Lam (1932: 204) and Shorea parvistipulata Heim (1891: 974) . The population consists of less than ten flowering individuals. The location at which the new Thismia specimens were discovered was also rich in other mycoheterotrophic species, including Epirixanthes elongata Blume (1823: 82) , Gymnosiphon aphyllus Blume (1827: 29) and Kalimantanorchis nagamasui Tsukaya, Nakajima & Okada (2011: 52) .

Taxonomic Note:— According to the classification of Jonker (1948), Thismia kinabaluensis is placed in sect. Thismia , subsect. Odoardoa in having six free equal perianth lobes and creeping vermiform roots. Thismia kinabaluensis is similar to T. inconspicua Sochor & Dančák (2017: 263) , T. chrysops Ridley (1895: 323) and T. cornuta Hroneš, Sochor & Dančák (2018: 110) ; all have very short stem, perianth tube bent or displaced from the ovary axis, and two club shaped appendages at the apical margin of the connective, but it is clearly distinguishable by the perianth tube with transverse bars inside, moderate funnel shaped yellow annulus, box shaped lateral appendage with very small trough surface, different sizes among perianth appendages ( Table 1), three anther appendages (one filiform between two club shaped). For a detailed comparison of morphological characters among T. kinabaluensis and its related species, see Table 1.

Based on the observations, the following can be inserted into the key to the Malaysian species of Thismia from Tsukaya & Okada (2012) with modifications after Tsukaya et al. (2017).

3. Flowers zygomorphic, geniculate

4. Appendages of perianth lobe hairy.................................................................................................................................... T. chrysops

4. Appendages of perianth lobe glabrous

5. No transverse bars in the perianth tube

6. Brownish perianth with 12 sepia-brown stripes, perianth appendages 2 mm, anther appendages 4 ........................... T. inconspicua

6. Translucent-white perianth with 12 pale pinkish stripes in upper part, perianth appendages 8–10 mm, anther appendages 2........... ............................................................................................................................................................................................. T. cornuta

5. Perianth tube with transverse bars............................................................................................................................. T. kinabaluensis

3. Flowers actinomorphic ................................................................................................................ 7 (no. 3 in Tsukaya & Okada 2012)

Figures

FIGURE 1. Thismia kinabaluensis. A–B. Flowering plant in its native habitat. C. Fruiting plants in its native habitat. D. Longitudinal section of perianth with transverse bars inside. E. Outer view of three pendulous stamens with lateral appendages and anthers. F–G. Capsule with stigma. Scale bar = 1 cm (A–C), 3 mm (D), 1 mm (E–G).