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 : 235-236

Thismia . annamensis K. Larsen & Averyanov (2007: 13 , Fig. 1 , 2 ) ( Fig. 2 )

Literature:— Kumar et al. (2017: 232), Nuraliev et al. (2019: 150, Fig. 1I )

TYPE: — VIETNAM. Dak Nong Province: Dak Glong District, Dak Plao Municipality, the territory of Ta Dung Nature Reserve, steep hill slopes at elevation 700–750 m, secondary open broad-leaved evergreen forest with bamboo and Pinus kesiya , around point N 11°51’47’’ E 107°56’59’’, 04 November 2005, L. Averyanov, T. V. Thao, N. T. Vinh HLF 5510 (holotype: LE: LE 01055866!).

Images of holotype available at http://herbariumle.ru/?t=occ&id=7511&rid=image_0014902

Description

Plant generally glabrous, branching by the formation of root suckers. Roots vermiform. Leaves up to 6, scattered, up to 14 mm long. Flowers rarely terminal and solitary, usually in terminal monochasial inflorescence of up to 7 flowers. Terminal flowers surrounded by an involucre of 3 bracts; lateral flowers surrounded by an involucre of (2)3 bracts (floral prophylls). Plane of inflorescence branching median; monochasium type a drepanium. Involucral bracts up to 12.5 mm long. Pedicel (internode between involucral bracts and ovary) up to 4.2 mm long (up to 28 mm long in fruit). Flower actinomorphic, (11)13–17(22) mm long from ovary base. Hypanthium narrowly to widely pyriform, (7.5) 9–18 mm long (excluding inferior ovary), (6)8–11(12) mm wide in the upper part; involucral bracts reaching most often from one third to two thirds of hypanthium; outer hypanthium surface with 12 raised longitudinal veins, minutely to strongly tuberculate, pale grayish brown to dark chestnut-brown, veins darker than surrounding tissue; inner surface with longitudinal bars connected by numerous short transverse bars, fenestrated, colouration similar to that of the outer surface with bars slightly to strongly contrasting with surrounding tissue. Annulus prominent, flat, almost circular, from whitish or light grayish brown to olive-brown, 4–8.3 mm in diam., with circular orifice 2.2– 5.1(6.5) mm in diam. Tepals free, subequal; perianth rotate (tepals spreading). Outer tepals broadly rhomboid, (3) 4–8 mm long and (4)5–8(9.5) mm wide. Inner tepals narrowly rhomboid, (2.6) 3–9 mm long, (2.5) 3–6 mm wide. Both outer and inner tepals irregularly finely crenulate along margin, adaxially smooth and abaxially strongly tuberculate (similar to outer surface of hypanthium), from light grayish brown to dark brown, slightly translucent, with midvein strongly raised abaxially and continuing into a filiform appendage, with a minute triangular tip of tepal blade free from the appendage lying above the appendage base; appendages straight or slightly arcuate, with their apices often bent downwards and aside, drooping in older flowers, 6.5–20.5(42) mm long, from whitish grey and light brown to dark brown and almost black, often with lighter apices. Stamens (2.8) 4–6.5 mm long, with long supraconnectives, fused laterally along their entire length except for the filaments and the very tips to form a stamen tube. Supraconnective apex rectangular, bearing 5 tooth-like processes; of them, 3 processes acuminate, tapering into hairs 0.8–1.2 mm long, and 2 processes arranged between the former 3, narrow, obtusely clavate, 0.6–1 mm long. Supraconnectives bearing skirt-like appendages at the outer (adaxial) side slightly below thecae. Each appendage wider than supraconnective, (1.7)2.4–3.5(4.2) mm wide, inclined towards the supraconnective apex and reaching or slightly exceeding it; main lamina of appendage widely attached to supraconnective tissue by lateral margins, broadly triangular, with more or less pronounced median fold, finely erose-denticulate along apical margin, at each lateral margin with a triangular projection inclined outside (towards hypanthium). Thecae adaxial (facing the hypanthium), separate, (0.5) 1–1.5 mm long. Androecial indumentum (apart from apical processes) of stiff needle-like hairs at the margins of appendages and 2 rows of shorter glandular hairs on the sides of each theca. Interstaminal glands present. Stamens white except distal portions of supraconnectives sometimes tinged with greenish blue and appendages white to dark blue. Ovary outside not delimited from hypanthium, obconic, 2.2–6(10) mm long, 3–5.5 mm wide towards apex. Placentas column-like. Stylar column cylindrical, slender, (0.3)0.9–1.1(2.5) mm long, 0.3–0.8 mm in diam., blue to almost black; styles ca. 1.5–2.5 mm below stamen apices, upright, deeply bidentate at apex and with an acute claw in the sinus between the teeth pointing upwards and inclined toward flower center (claw ranging from hardly discernible to longer than style teeth), 1–1.5 mm long, bearing densely finely papillose stigmas, dark blue to almost black. Fruit brown to almost black; seeds ellipsoid, 0.3–0.35 mm long, light yellowish-brown, with long narrow processes of testa at poles.

Etymology: —The specific epithet “ annamensis ” refers to the former Annam area corresponding to the central part of Vietnam, where the type of this species was collected.

Phenology: —Flowering and fruiting from late May to November (January).

Additional specimens examined:— VIETNAM. Kon Tum Province: Kon Plong District, Mang Canh Municipality, Thach Nham Protection Forest , 14 km NNE of Mang Den town, in the forest, near river, N 14°43’54’’ E 108°18’01’’, 1100 m a.s.l., 05 June 2016, M. S. Nuraliev, A. N. Kuznetsov, S. P. Kuznetsova 1644 ( MW) ; Quang Ngai Province: Ba To District , N 14°35’54’’ E 108°43’24’’, 906 m a.s.l., 23 January 2016, Nguyen Quoc Dat, Nguyen Hieu Cuong, Dinh Nhat Lam Pl _ Q. NG 0025 ( SGN) ; Gia Lai Province: K’Bang District, Son Lang Municipality, Kon Chu Rang Nature Reserve , 29 km ESE of Mang Den town, forest, river bank, N 14°30’55’’ E 108°32’50’’, 1000 m a.s.l., 26 May 2016, M. S. Nuraliev 1562 ( MW) ; Dak Lak Province: Lak District, Bong Krang Municipality, Chu Yang Sin National Park , 12 km S of Krong Kmar village, forest, near small river, N 12°23’40’’ E 108°20’55’’, 1100 m a.s.l., 28 May 2014, M. S. Nuraliev 999 ( MW) ; same location, 27 May 2019, S. V. Yudina, M. S. Nuraliev 16 ( MW) ; Khanh Hoa Province: Hon Ba Nature Reserve , N 12°07’38.05’’ E 108°56’32.54’’, 1378 m a.s.l., 2014, Truong Ba Vuong BV 175a ( MW) .

Distribution: —Endemic to Vietnam, where it occurs in several southern provinces: Kon Tum (Thach Nham Protection Forest), Quang Ngai (Ba To District), Gia Lai (Kon Chu Rang Nature Reserve), Dak Lak (Chu Yang Sin National Park), Dak Nong (Ta Dung Nature Reserve), Khanh Hoa (Hon Ba Nature Reserve).

Notes: —1. Thismia annamensis is characterised by remarkable structure of styles that are bidentate and bear an apical claw. The claw is usually quite prominent with respect to its size. The largest claws were found in the specimens Nguyen Quoc Dat et al. Pl_Q.NG 0025 and Truong Ba Vuong BV175a, claws are somewhat smaller in Yudina et al. 16 and hardly recognizable in Nuraliev 1562. We suppose that the claws are not described in the protologue of T. annamensis ( Larsen & Averyanov 2007) because they were overlooked during investigation of the type material.

2. Flowers of Thismia annamensis are significantly diverse in their colouration and proportions of their parts. Particularly, there are more intensively coloured individuals (including the type specimen) with certain flower parts being dark brown to almost black, and those more pale and whitish. There are intermediate cases between these extremes, and sometimes variation in colour is found in the same population. With respect to the flower size and shape, the most variable characters are the hypanthium shape, diameter of the annulus and its orifice and length of the tepal appendages.

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.