Thismia brunneomitra Hroneš, Kobrlová & Dančák, 2015

Hroneš, Michal, Kobrlová, Lucie, Taraška, Vojtěch, Popelka, Ondřej, Hédl, Radim, Sukri, Rahayu Sukmaria, Metali, Faizah & Dančák, Martin, 2015, Thismia brunneomitra, another new species of Thismia (Thismiaceae) from Ulu Temburong, Brunei Darussalam, Phytotaxa 234 (2), pp. 172-178 : 173-176

publication ID	https://doi.org/ 10.11646/phytotaxa.234.2.7
persistent identifier	https://treatment.plazi.org/id/DB48879E-FFD7-FFDA-FF2C-0E3780B504B0
treatment provided by	Felipe
scientific name	Thismia brunneomitra Hroneš, Kobrlová & Dančák
status	sp. nov.

Treatment

Thismia brunneomitra Hroneš, Kobrlová & Dančák View in CoL , sp. nov., Fig. 1 View FIGURE 1

Similar to Thismia episcopalis , but differing in having 1–2 flowers per individual, presence of three short processes at the apex of the mitre, free apical margin of the stamen connective with two broad obtusely triangular lateral lobes and narrowly triangular middle lobe, large entire wing-like lateral appendage of the connective and brown to blackish colour of the perianth tube ( Table 1).

Type: — BRUNEI DARUSSALAM. Temburong distr.: Kuala Belalong, right bank of the stream Sungai Mata Ikan , ca. 150 m NW from the Kuala Belalong Field Studies Centre. Coordinates WGS 84: N 04°32´ 51.2˝; GoogleMaps E 115°09´24.5˝; elevation ca. 105 m a.s.l., 3 February 2015. Hroneš & Kobrlová 402015 (holotype BRUN! [herbarium specimen, accession number B031129 ], isotype OL! [herbarium specimen, accession number 31594]) .

Description: —Perennial achlorophyllous mycoheterotrophic herb, 6.2–8 cm tall. Roots coralliform, slightly branched towards the apex, whitish. Stem 4.5–6.5 cm tall, ascending to erect, simple, one or two flowered, sparsely shortly hairy, mostly pale brown ( Figs 1A View FIGURE 1 , 2A, B View FIGURE 2 ), blackish when young ( Fig. 2C View FIGURE 2 ); pedicel dark brown to blackish and elongating after anthesis ( Fig. 2D View FIGURE 2 ). Leaves 6–7, spirally arranged, well-spaced, scale-like, triangular, acute, entire, 3.5–5 mm long, 2–3 mm wide at base, pale brown, glabrous. Floral bracts three, similar in shape to leaves but slightly larger, 5.5– 7 mm long, 3–3.5 mm wide at base, keeled, enveloping base of flower, pale brown. Flowers bisexual, actinomorphic, 1.6–1.7 cm long, 0.9–1 cm wide at top of perianth tube; perianth tube urceolate, of 6 fused tepals; outer surface with six longitudinal ribs, dark brown to blackish when young, later pale brown to brown with 12 vertical dark brown stripes; outer tepal lobes absent; inner tepal lobes well-developed, connate at top and forming mitre with three holes, 5–7 mm tall; holes reniform-elliptic to almost rounded, 4–6 mm wide, 2–4 mm high; mitre dark brown to blackish when young, at maturity dark brown with paler brown to reddish-brown apex and margins of holes, topped by three short obtuse processes ( Figs 1B View FIGURE 1 , 2E View FIGURE 2 ). Annulus absent. Stamens 6, hanging from top of perianth tube, bluish to purplish ( Figs 2G–I View FIGURE 2 ); connectives flattened, ribbon shaped, connate to form tube ; individual connective with two tufts of glandular hairs on adaxial side and three lobes on free apical margin; lateral lobes wide, obtusely triangular; middle lobe narrowly triangular ( Figs 1D View FIGURE 1 , 2I View FIGURE 2 ); each lobe terminated by tuft of glandular hairs; lateral appendage of connective flattened, large, wing-like, protruding outwards to the perianth tube, with marginal glandular hairs; thecae whitish ( Figs 1C View FIGURE 1 , 2G View FIGURE 2 ). Style trifid, papillose, terminated by very shallowly notched stigmas ( Fig. 2F View FIGURE 2 ); ovary obconical, with six vertical ribs on surface and blackish horizontal line at apex. Capsule cup-shaped, brown to dark brown, sparsely hairy, topped by basal ring of perianth tube and withered style ( Fig. 2D View FIGURE 2 ). Seeds not seen.

Variability: —The basic colour of the perianth tube and the mitre varies from almost black to brown-reddish. The number of flowers in one individual varies from one to rarely two.

Habitat and ecology: —Shaded understory of lowland mixed dipterocarp forest. The only known site is in a ravine of a small stream. The terrain is steep, rocky and somewhat disturbed, with patches of bare mineral soil. Plants were found primarily in these bare patches with several individuals growing on a rock crevice just next to the stream in association with Diplazium cordifolium Blume (1828: 190) , Epipremnum falcifolium Engler (1898: 11) , Mapania monostachya Uittien (1935: 194) , Schismatoglottis asperata Engler (1879: 297) and Selaginella involvens agg. Several other mycoheterotrophic species were recorded around, within a distance of 5 m: Epirixanthes elongata Blume (1823: 82) , E. papuana J.J. Smith (1912: 486) , Sciaphila densiflora Schlechter (1912: 87) , S. secundiflora Thwaites ex Bentham (1855: 10) and Gymnosiphon aphyllus agg.

Distribution: — Thismia brunneomitra was found near the Kuala Belalong Field Studies Centre in the Temburong district of Brunei Darussalam. The only known population occurs on the right bank of the small stream Sungai Mata Ikan, approximately 100 m from its confluence with the Belalong River and near the “Ashton trail” forest circuit.

Conservation status: —Population of T. brunneomitra occurs within the designated research zone of Ulu Temburong National Park, to which public access is restricted. The type locality and its surroundings are thus protected from logging or other destructive anthropogenic activities. However, given that after a thorough search, no more than 15 individuals were noticed, and that the population is situated near relatively frequented forest trail, we suggest evaluating the species as critically endangered (CR) according to the IUCN Red List Categories and Criteria ( IUCN 2012).

Etymology: —Name of the species is composed from Latin words brunneus (brown) and Greek mitra, referring to the typical colour and shape of the flowers.