Thismia, Griffith, 1845

Nuraliev, Maxim S., Yudina, Sophia V., Truong, Ba Vuong, Do, Thi Xuyen, Luu, Hong Truong, Kuznetsov, Andrey N. & Kuznetsova, Svetlana P., 2020, A revision of the family Thismiaceae (Dioscoreales) in Cambodia, Laos and Vietnam, Phytotaxa 441 (3), pp. 229-250 : 236

Thismia . bokorensis Suetsugu & Tsukaya in Suetsugu et al. (2018: 65, Fig. 1 , 2 )

Literature:— Tagane et al. (2017: 761, Fig. I, as “ Thismia sp. ”)

TYPE: — CAMBODIA. Kampot Province: Bokor National Park, evergreen forest near a stream, N 10°36’33.6” E 104°04’12.6”, elev. 370 m, 10 August 2013, S. Tagane, K. Fuse, M. Yokota, M. Zhang, P. Chhang 5857 (holotype: TNS, in the spirit collection).

Description

Plant generally glabrous. Roots vermiform. Leaves scattered, up to 7 mm long. Inflorescence terminal, monochasial, of 2–3 flowers. Flowers surrounded by involucral bracts up to 7 mm long. Pedicel and ovary together 6–7 mm long. Flower actinomorphic. Hypanthium 8–9 mm long, 5 mm wide near the apex, pure white, longitudinally finely grooved with 12 rough low ribs; inner surface finely irregularly manicate-rugulose, without transverse bars. Annulus prominent, flat, broad, light yellow. Outer tepals broadly triangular, 1.2 mm long, 2.4 mm wide, light yellow, apex broadly obtuse or rounded. Inner tepals free, narrowly triangular, 2.6 mm long, 2.1 mm wide, light yellow, bearing a filiform appendage at apex; appendage 8 mm long. Stamens with long supraconnectives, fused laterally along their entire length except for the filaments and the apices to form a stamen tube. Free apical part of each supraconnective bears 3 narrowly triangular teeth; each tooth apically tapering into a hair ca. 1 mm long. Supraconnectives bearing wing-like appendages at the outer (adaxial) side below thecae; each appendage flattened, not exceeding apical part of supraconnective, margin slightly dentate, with glandular hairs. Interstaminal glands present. Ovary white. Placentas column-like. Stylar column 0.5 mm long; styles shallowly bilobed, 1 mm long. Fruit white to pale brown.

Etymology: —The specific epithet “ bokorensis ” apparently refers to the Bokor National Park and Bokor Mountain, the type location of this species.

Phenology: —Flowering and fruiting in August.

Distribution: —Endemic to Cambodia, Bokor National Park. Only known from the type collection.

Notes:— Thismia bokorensis is morphologically intermediate between T. javanica and T. tentaculata . It differs from T. javanica mainly by manicate-rugulose inner hypanthium surface without transverse bars and by uniformly white outer hypanthium surface. The only prominent difference of T. bokorensis from T. tentaculata is the tridentate supraconnective apex. The other floral features indicated as diagnostic by Suetsugu et al. (2018) are regarded here as having little taxonomic importance. Particularly, the wing-like appendage of the supraconnective not exceeding the apical part of the connective does not distinguish T. bokorensis from any of the two similar species because they in fact show nearly the same morphology (in T. javanica and T. tentaculata , the appendage ± reaches the bases of apical teeth of supraconnective); the length and colour of the appendages of inner tepals are variable to a significant extent in T. javanica and T. tentaculata . The morphological comparison is also currently complicated because photos of the inner structure of flower of T. bokorensis are not available. The description of T. bokorensis is based on a single observed flower ( Suetsugu et al. 2018), and therefore it is likely that some morphological variation of this species will be disclosed as more specimens and populations become known. It is possible that future studies will show taxonomic identity of T. bokorensis with either T. javanica or T. tentaculata ; both options would be in concordance with data on species geographical distribution.

Figures

FIGURE 1. Distribution map of the species of Thismia in Cambodia, Laos and Vietnam.

FIGURE 2. Thismia annamensis. A–D. Nuraliev 1562; E–G. Nuraliev 999. H. Nguyen Quoc Dat et al. Pl_Q.NG 0025; all photos by M. Nuraliev except for H by Nguyen Quoc Dat. A. Habit. B, E. Flower, apical view. C. Annulus and stamens, lateral view. D. Flower, longitudinal section. F. Flower with a longitudinal half of hypanthium removed, oblique-bottom view. G. Longitudinal section of distal part of flower showing stamen structure. H. Styles, apical view.