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 : 244-247

Thismia . tentaculata K. Larsen & Averyanov (2007: 16 , Fig. 4 , 5 ) ( Fig. 6 )

Literature:— Ho et al. (2009: 605), Wu et al. (2010: 124), Kumar et al. (2017: 232), Guo et al. (2019: 2, Fig. 1 , 3 )

TYPE: — VIETNAM. Quang Tri Province: Da Krong District, Huc Nghi Municipality, in vicinities of La To village, primary broad-leaved evergreen lowland forest on montane hills composed with shale, around point N 16°29’16’’ E 107°00’32’’, at elevation about 414 m, 26 March 2006, L. Averyanov, P. K. Loc, P. V. The, N. S. Khang, N. V. Huy, D. C. Tri, L. M. Tuan, T. T. Tu, P. K. Vuong, P. V. Bao, P.X. Dieu, H. T. Phuong HLF 6251 (holotype: LE: LE 01055867!).

Images of holotype available at http://herbariumle.ru/?t=occ&id=7512&rid=image_0014905

Description

Plant generally glabrous. Roots vermiform. Leaves several, scattered, up to 8 mm long. Flowers rarely terminal and solitary, usually in terminal monochasial inflorescence of up to 4 flowers. Terminal flowers surrounded by an involucre of 3 bracts; lateral flowers surrounded by an involucre of 2 bracts (floral prophylls). Involucral bracts up to 8 mm long. Pedicel (internode between involucral bracts and ovary) ca. 0.5 mm long. Flower actinomorphic, 12.4–13 mm long from ovary base, with white, yellow and red colours (flower parts mainly orange-red in plants from Hon Ba). Hypanthium broadly obconic to obovate, 7.5–12 mm long (excluding inferior ovary), 5–7 mm wide in the upper part; involucral bracts reaching about one third of hypanthium or sometimes less; outer hypanthium surface with 12 finely impressed longitudinal veins, finely tuberculate, pure white and sometimes with antetepalous veins indistinctly tinged with red in the upper part; inner surface finely irregularly manicate-rugulose without transverse bars (ornamentation more similar to transverse bars in plants from Hon Ba), colouration similar to that of the outer surface. Annulus prominent, flat, almost circular to roundish-hexagonal, bright yellow, ca. 4 mm in diam., with circular orifice ca. 2.5 mm in diam. Outer tepals spreading or reflexed down, nearly isosceles triangular, 1.4–2.5 mm long, 2.5–3 mm wide at base, light yellowish or tinged with red, translucent, margin entire, apex broadly obtuse or rounded. Inner tepals free, spreading, narrowly triangular, ca. 2.3–3.2 mm long, 2.1–3 mm wide at base, light yellowish at base and reddish towards apex, with entire translucent margin, 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, (5.5) 13–17 mm long, red, often lighter towards apices. Stamens 3–5 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, with 2 teeth tapering into hairs ca. 0.6 mm long, and with a similar hair in the sinus between the teeth; the middle hair sometimes with dilated base resembling of a small third tooth. Supraconnectives bearing skirt-like appendages at the outer (adaxial) side slightly below thecae. Each appendage as wide as or wider than supraconnective, 1.8 mm wide, inclined towards the supraconnective apex and reaching it; main lamina of appendage widely attached to supraconnective tissue by lateral margins, triangular-trapezoid, finely crenulate or nearly entire along apical margin, at each lateral margin with a triangular projection inclined outside (towards hypanthium); appendage margins hairy. Thecae adaxial (facing the hypanthium), separate, ca. 0.9 mm long. Interstaminal glands present. Stamens white but yellowish towards base, with bright red interstaminal spots at junction of filaments and annulus. Ovary outside not delimited from hypanthium, obconic, ca. 1.6–2.5 mm long, ca. 2.4–3 mm wide towards apex. Placentas most probably column-like. Stylar column cylindrical, 0.6–1.1 mm long, 0.4–0.6 mm in diam., white; styles ca. 3 mm below stamen apices, upright, simple, 0.6–0.8 mm long, bearing densely finely papillose stigmas, white. Fruit white to light brown; seeds ellipsoid, 0.2–0.3 mm long, with short narrow processes of testa at poles.

Etymology: —The specific epithet “ tentaculata ” refers to the appearance of the appendages of inner tepals of this species that resemble tentacles of a boiled shrimp.

Phenology: —Flowering and fruiting from (February) March to August.

Additional specimens examined: — VIETNAM. Khanh Hoa Province: Cam Lam District, Suoi Cat Commune, Hon Ba Nature Reserve , Hon Ba Peak , N 12°07’07’’ E 108°56’53’’, 1508 m, 19 May 2012, Luu Hong Truong, Tran Gioi, Nguyen Thien Tich KH 163 ( MW: MW-DigiPic0000018; SGN) ; 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 175b ( MW) ; Khanh Hoa Province: Khanh Son District, Son Trung Commune, Hon Ba Nature Reserve , O Kha , N 12°02’51.9’’ E 108°59’44.9’’, 1130 m, 13 July 2013, Luu Hong Truong, Tran Gioi, Nguyen Thien Tich, Dinh Quang Diep, Nguyen Thanh Trung KH 638 ( MW: MWDigiPic0000019; SGN) .

Distribution: — Hong Kong (Tai Mo Shan); Vietnam: Quang Tri Province (Da Krong District), Khanh Hoa Province (Hon Ba Nature Reserve).

Notes: —1. Thismia tentaculata was initially described to have “bidentate filaments without hairs at apex” ( Larsen & Averyanov 2007: 19). However, the hairs at apices of teeth in each supraconnective as well as the third hair in the sinus between the teeth are discernible on the photos of the type material. The hairs are also clearly visible on the published photos of representatives of T. tentaculata from Hong Kong ( Guo et al. 2019: Fig. 1 ) and in the specimens studied here.

2. The length and colour of the appendages of inner tepals is quite variable across the available material of T. tentaculata , and therefore we find it impossible to use these characters for delimitation T. tentaculata and similar species.

3. Collections from Hon Ba Nature Reserve (Luu Hong Truong et al. KH 163 and KH 638, Truong Ba Vuong BV175b) differ from the type of T. tentaculata and from the population of this species in Hong Kong ( Ho et al. 2009, Guo et al. 2019) in overall flower colouration with prevalence of orange-red (light orange-red hypanthium with 12 darker veins, orange-red annulus and tepals, dark orange-red appendages of inner tepals, stamens tinged with orange and their appendages especially so), more obovate flower shape (i.e., with hypanthium conspicuously narrowing towards apex and annulus much narrower than hypanthium) and inner hypanthium surface with ornamentation similar to transverse bars. We provisionally assign these collections to T. tentaculata mainly based on their bidentate stamen apices and argue that further investigations of the plants from Hon Ba are needed to verify their taxonomic and phylogenetic affinities.

4. The photographs of T. tentaculata from Hong Kong published by Guo et al. (2019) show androecium with three equal well-pronounced teeth on each stamen apex. Meanwhile, the number of stamen teeth (two vs. three) is one of the main differences between T. tentaculata and the morphologically close T. javanica . The presence of tridentate stamens in the Hong Kong population of T. tentaculata has not been confirmed to date by specimen investigation. However, it is thus possible that the number of stamen teeth varies within certain species of Thismia . This supposed phenomenon would be indirectly consistent with the uniform presence of three apical hairs in stamens of T. tentaculata . On the other hand, the possibility cannot be excluded that the plants on photographs published by Guo et al. (2019) in fact belong to T. javanica .

Figures

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

FIGURE 3. Thismia javanica. A–D. Do Thi Xuyen et al. BHH 800, photos by Do Thi Xuyen and SEM image by S. Yudina; E–I. Truong Ba Vuong et al. BV426, photos by Truong Ba Vuong. A, E. Flower, apical view. B, F. Flower, lateral view. C. Longitudinally opened and flattened hypanthium showing stamens. D. Supraconnective, abaxial view (SEM). G. Flower, oblique view. H. Flower with longitudinally opened hypanthium (three stamens removed). I, Three stamens, adaxial view.

FIGURE 4..Thismia mucronata. A, B. Inflorescence, lateral and oblique views. C. Mitre, oblique view. D, E. Young fruit (soon after hypanthium abscission), apical and lateral views. F, G. Excavated root system showing root suckers. All photos by M. Nuraliev from Nuraliev 1009.

FIGURE 5..Thismia puberula. A–C. Lateral views of flowers showing variation of flower shape. D, E. Mitre, oblique and apical views. F. Perianth, showing inner surface of mitre. All photos by M. Nuraliev from Yudina et al. 15.

FIGURE 6..Thismia tentaculata, non-typical plants from Hon Ba Nature Reserve.A–C. Luu Hong Truong et al. KH 163; D–G. Luu Hong Truong et al. KH 638; all photos by Luu Hong Truong. A, B. Flower, apical and lateral views. C. Longitudinally dissected hypanthium showing stamens. D. Flower, oblique view. E. Flower, longitudinal section. F, G. Androecium, oblique and lateral views.