Burmannia itoana Makino (1913: 1

Nuraliev, Maxim S., Yudina, Sophia V., Truong, Ba Vuong, Dang, Van Son, Kopylov-Guskov, Yury O., Lyskov, Dmitry F., Kuznetsov, Andrey N., Kuznetsova, Svetlana P. & Zhang, Dianxiang, 2022, A checklist of Burmanniaceae in Eastern Indochina with a new record from Vietnam, Burmannia itoana, Phytotaxa 544 (1), pp. 61-70 : 62

Burmannia itoana Makino (1913: 1 , Fig. 1 ) ( Fig. 2 )

Literature:— Jonker (1938: 153), Wu (1977: 185), Wu & Chen (1981: 173), Ohashi et al. (2000: 143), Wu et al. (2010: 123), Hsieh et al. (2011: 17), Tsukaya (2016: 195).

LECTOTYPE, designated by Jonker (1938: 154):— JAPAN. [Okinawa Prefecture:] Yaeyama archipelago, Ishigaki Island, Mt. Fazan in Okawa-mura , 28 June 1891, Tanaka S. s.n. (herbarium unknown).

Description (based on Nuraliev 2444):

Herb terrestrial, non-photosynthetic, perennial, entirely glabrous; the entire plant violet-blue. Roots attached at stem base, several, filiform. Stem branching at basal (subterranean) part, light violet-blue, 7–10 cm long. Leaves on aerial stem several, scattered, appressed to stem or slightly spreading, scale-like, narrowly triangular, light violet-blue, up to 4 mm long and 2.5 mm wide at base, apex acute to acuminate; leaves on basal part of stem crowded, scale-like, white, smaller. Inflorescence a terminal botryoid of up to 3 flowers (a terminal flower and 1–2 flowers in axils of involucral bracts and upper stem leaves); sometimes stem with a solitary terminal flower. Involucral bracts below terminal flower 2, spirally arranged, similar to stem leaves but up to 5 mm long, initially appressed to flower base. Lateral flowers each with a single transversal bracteole. Pedicel (internode between involucral bracts and ovary) 1.5–2 mm long. Flower erect, actinomorphic, externally (including abaxial sides of tepal lobes) bright violet-blue, 8–11 mm long in bud; perianth wings 3, semi-cuneate (to shallowly semi-pandurate), running from ovary base to bases of outer tepal lobes, 2–2.5 mm wide. Floral tube cylindrical, triangular in cross section, whitish inside, 5–6 mm long, 2–2.5 mm wide. Outer tepal lobes 3, spreading (when fully open), fleshy, triangular, adaxially densely papillose, adaxially pale violet, 1.5 mm long, 1.5 mm wide at base, single-margined, apex obtuse. Inner tepal lobes 3, semi-orbicular, adaxially densely papillose, adaxially pale violet, ca. 0.3–0.5 mm long and wide, single-margined. Stamens 3, inserted on the inner surface of floral tube just below tepal lobes, opposite inner tepals, sessile, white, 1 mm long, 1.3 mm wide; connective thick and broad (T-shaped), bearing 2 thecae on lateral arms, with 2 apical crests and a short acute basal spur; apical crests as broad as thecae, covered with long hairs. Ovary inferior, sometimes with 3 white patches between wings, ca. 2–3 mm long, ca. 2.5 mm wide, trilocular proximally and unilocular distally, with numerous tiny ovules; common style narrowly cylindrical, white, slightly shorter than floral tube, with three style branches terminating into fan-shaped stigmas; stigmas placed above stamens and below tepal lobes. Fruit not seen.

Additional illustrations of floral structure of this specimen are provided by Yudina et al. (2022).

Note: —Although Zhang (1999) considered B. itoana to be cleistogamous, our observations revealed fully open fresh flowers of this species.

Ecology and phenology: —Subtropical and tropical wet evergreen forests at elevations of 300–1200 m. In Ta Xua Nature Reserve, only a single individual was found, whereas in Song Thanh Nature Reserve the species is locally rather common along banks of a small river. Flowering and fruiting from April to December.

Distribution: — Japan: Okinawa Prefecture (Okinawa Islands and Yaeyama archipelago); China: provinces Guangdong, Guangxi, Hainan, Hong Kong, Taiwan, Yunnan; Vietnam: Son La Province (Ta Xua Nature Reserve), Quang Nam Province (Song Thanh Nature Reserve) ( Fig. 3 ).

Additional specimens examined: — VIETNAM. Son La Province: Phu Yen District, Ta Xua Nature Reserve, open forest on local ridge, 21°21’06’’N 104°40’12’’E, elev. 770 m, 09 October 2019, Nuraliev M. S., Kopylov-Guskov Yu.O., Lyskov D.F. 2886 (spirit material: MW); Quang Nam Province: Nam Giang District, Song Thanh Nature Reserve, forest, river bank, 15°34’12’’N 107°22’39’’E, elev. 1050 m, 30 April 2019, Nuraliev M. S. 2444 (spirit material: IBSC, MW).

Figures

FIGURE 1. Representative diversity of flowers of Vietnamese Burmannia. A, B. B. chinensis (Truong Ba Vuong BV999). C, D. B. coelestis (Truong Ba Vuong BV1000). E, F. B. disticha (Vislobokov 19037). G, H. B. lutescens (Nuraliev, Lyskov NUR 3120). I, J. B. nepalensis (Nuraliev NUR 1420). K, L. B. oblonga (Yudina, Nuraliev 1). Photos: A–D by Truong Ba Vuong; E–L by M.S. Nuraliev.

FIGURE 2. Burmannia itoana. A. Habit.B, C. Flower, oblique view. D. Flower, top view.E–G. Flower, side view.H. Flower, longitudinal section. I. Distal portion of dissected floral tube viewed from inside, showing stamens. J. Underground part and base of aerial stem. Nuraliev 2444. Photos by M.S. Nuraliev.

FIGURE 3. Distribution of Burmannia itoana in Vietnam.