Biermannia brachystachys (Schltr.) Aver., 2025

Averyanov, Leonid V., Nguyen, Van Canh, Vuong, Truong Ba, Quang, Bui Hong, Nguyen, Khang Sinh, Le, Tuan Anh, Binh, Tran Duc, Maisak, Tatiana V. & Nguyen, Cuong Huu, 2025, New orchids in the flora of Vietnam X (Orchidaceae, Orchidoideae, tribe Orchideae, Epidendroideae, tribes Gastrodieae, Arethuseae, Cymbidieae, and Vandeae), Phytotaxa 681 (1), pp. 20-54 : 31-36

Biermannia brachystachys (Schltr.) Aver. , comb. nov.

( Fig.6 & 7 )

≡ Chamaeanthus brachystachys Schltr. in Smith (1905: 552), Comber (1990: 300), Wood & Cribb (1994: 366), Schuiteman & Vogel

(2000: 91), Yee et al. (2005: 144).

Type: — MALAYSIA. Central Java & Djokjakarta, “Java: Tegal (Raciborski); Djokjakarta (Raciborski)” (Schechter in Smith 1905: 552). Syntypes destroyed in B (fide Wood & Cribb 1994: 366). Possible (questionable) isosyntype in Harvard University Herbaria ( AMES 00106675).

Description (based on specimens from Vietnam):— Herb monopodial, miniature, epiphytic, glabrous. Stem (0.8)1– 1.6(1.8) cm long, completely covered by distichous leaf sheaths, slightly flattened, with many pale green wiry roots clustered near stem base. Leaves (5)6–9(10), sessile, jointed, obliquely lanceolate, falcate, (3.5)4–6(7) cm long, (4)5– 7(8) mm wide, apex with two obtuse oblique unequal lobes. Inflorescence axillary, subdense, head-like raceme, down directed, glabrous; peduncle straight, terete, (1)1.1–1.3(1.4) cm long, with (1)2–3(4) distant sterile narrowly triangular subacute bracts, (0.8)1–1.2(1.3) mm long, 0.5–0.7 mm wide; rachis (3)3.5–4.5(5) mm long, with several distichous triangular floral bracts; floral bracts close to each other, narrowly triangular, acute, sharp. persistent, (1)1.2–1.3(1.4) mm long, 0.5–0.6 mm wide; 1–4(5) flowers blooming simultaneously; inflorescence developing for a long time and thus flowers occupy its apical half. Flowers opening during a few morning hours, shortly fugacious, resupinate. Pedicel and ovary light green, glabrous, terete, shallowly 6-grooved, suberect, straight or slightly recurved, (2)2.2– 2.6(2.8) mm long, 0.4–0.5 mm in diameter. Sepals free, subequal, broadly lanceolate, acuminate, tapering from broad base to the apex, straight, (6.4)6.6–7(7.2) mm long, (1.4)1.5(1.6) mm wide near the base, light yellowish with yellow apical third. Petals narrowly triangular or broadly lanceolate, acute, straight, as broad as sepals but twice shorter, light yellowish with yellow apical third. Lip simple, triangular, trilobed, very fleshy, recurved, movably attached to the apex of column foot, lying almost parallel to column, (1.5)1.6(1.7) mm long and wide, entirely uniformly yellow; side lobes half-circular, suberect, very thin, (0.8)0.9–1(1.1) mm broad, 0.3–0.4 mm tall, entire or finely erose along the margin; median lobe conoid, fleshy, 0.6–0.7 mm long, obtuse to subacute; disc without ornamentation. Column erect, stout, white or white with light greenish tint, (0.7)0.8–1(1.1) mm tall and wide; stigma almost circular, concave; column foot free, forward directed, as long as column. Operculum helmet-shaped, (0.6)0.7(0.8) mm in diameter, with flat recurved margin, without beak. Pollinia 2, globular, 0.3–0.35 mm in diameter, entire or with a hardly visible cavity; stipe oblong, 0.2–0.25 mm long, viscidium half this size, ovate to almost circular. Fruit not seen.

Ecology and phenology: —(in Vietnam) Monopodial canopy epiphyte. Primary evergreen broad-leaved submontane forests on karstic limestone at elevations of 800–1000 m a.s.l. Flowers in June–July.

Distribution:— Vietnam (Son La Province, Thuan Chau District). Malacca Peninsula, Thailand?, Java, Borneo.

Conservation status:— Biermannia brachystachys is presently known in Vietnam from a single site with one documented population. Nothing is known about the population and ecology of this species. Accordingly, this species can be assessed as Data Deficient (DD) for Vietnam. The species is known to be distributed in Borneo, Jawa and Thailand.

Notes: —The genus Biermannia prior to this study included thirteen accepted species distributed from northeastern India and southern China through the Indochinese and Malay Peninsulas to Sumatra, Java and Borneo ( Comber 1990, 2001, Seidenfaden & Wood 1992, Pearce & Cribb 2002, Rao 2006, Chen et al. 2009, Chase et al. 2015, Averyanov et al., 2018a,b, Ding et al. 2019). All species of this genus are miniature, canopy epiphytes with small, unattractive fugacious flowers lasting only few hours in the morning. As a result, these orchids are easily overlooked in botanical surveys, poorly represented in herbaria and remain infrequently inventoried in local floras throughout its range. Vietnam seems to be an area of the highest species diversity of this genus with six earlier recorded species (Seidenfaden 1992, Averyanov 1994, Pham H.H. 2000, Averyanov & Averyanova 2003, Nguyen et al. 2005, Xu et al. 2010, Zhou et al. 2016, Averyanov et al., 2018a,b) and two species reported additionally in this study.

Biermannia brachystachys was originally described as a type species of Chamaeanthus Schltr. in Smith (1905: 552), the genus which, actually, cannot be morphologically segregated from the earlier established Biermannia King & Pantling (1898a: 591) . Formally the descriptions of both genera look very similar and do not present individual generic differences ( King & Pantling 1898a, Smith 1905, Comber 1990: 300, Shuiteman & Vogel 2000, Pridgeon et al. 2014, Pham 2021). On the basis of morphological studies of the currently accepted species, we do not see characters of a generic level that can segregate these taxa and hence follow the concept regarding these two genera as congeneric with Biermannia as a valid name ( Seidenfaden & Wood 1992, Averyanov et al. 2023a).

Biermannia brachystachys is remarkable for its short fleshy lip that well segregates this species from all its congeners. Two superficially similar plants with short lip recently reported from northeast India (Arunachal Pradesh) as Biermannia arunachalensis A.N. Rao (2006: 29) and B. jainiana S.N.Hegde & A.N.Rao (1984: 97) belong surely to the genus Thrixspermum sect. Dendrocolla and should be named as Thrixspermum arunachalensis (A.N.Rao) Aver. , comb. nov. (≡ Biermannia arunachalensis A.N. Rao, 2006 , Rheedea 16, 1: 29, fig. 1) and Thrixspermum jainiana (S.N.Hegde & A.N.Rao) Aver. , comb. nov. (≡ Biermannia jainiana S.N.Hegde & A.N.Rao, 1984 , Bulletin of the Botanical Survey of India 26: 97). Both plants may be close to Thrixspermum pygmaeum (King & Pantl.) Holttum 1960: 275 (≡ Sarcochilus pygmaeus King & Pantling 1898b: 207 ) according to the structure of their inflorescence, floral morphology and the lip glandular indumentum.

The main distribution of Biermannia brachystachys comprises Java and Borneo. The species was also reported from the single location in Malacca Peninsula ( Malaysia, Perlis State) near the border with Thailand ( Yee et al. 2005). Indirect indication of this species for Thailand ( Shuiteman & Vogel 2000) provides no citation of voucher specimens and remains questionable. The discovery of B. brachystachys in northern Vietnam looks rather unexpectable with documented location distant from closest mainland population in Malacca Peninsular more than 2000 km to the NEE. Specimens of Biermannia brachystachys newly discovered in Vietnam differ from the plants in the area of the main distribution in rather long leathery (not fleshy) leaves, but in floral characters fit almost entirely with an available drawing of the type ( Smith 1905).

Studied specimen: — VIETNAM, Son La Province: Thuan Chau District, Phong Lai Commune, Phieng Long Village, foots of Pha Din Pass area, remnants of primary evergreen broad-leaved forests on limestone mountains at elevation of 800–1000 m a.s.l., epiphytic perennial herbs, 5 July 2023, K.S. Nguyen & T.V. Lo, AL2233a (LE: LE01276688 https://en.herbariumle.ru/?t=occ&id=235152, photos of plants used for preparation of the voucher specimen LE01124273 https://en.herbariumle.ru/?t=occ&id=181365, LE01255217 https://en.herbariumle.ru/?t=occ&id=241571, drawing LE01255181 https://en.herbariumle.ru/?t=occ&id=234691).

Figures

FIGURE 6. Biermannia brachystachys. A. Flattened flowering plants. B. Inflorescences and leaf, adaxial and abaxial side. C. Intact inflorescences.D. Separated inflorescences.E. Portion of rachis, floral bract and flower, with artificially recurved lateral sepal. F. Flowers, side view, lateral sepal removed. G. Flower, front view. H. Flower bract and flattened parts of flower. I. Ovary, column, column foot and lip, side and half-side views. J. Lip, views from different sides. K. Column, half-side and front views, with anther cap and with anther cap removed. L. Operculum, views from different sides. Photos by K.S. Nguyen, from the specimen AL2233a. Photo correction and design by L. Averyanov and T. Maisak.

FIGURE 7. Biermannia brachystachys.A. Flattened flowering plants. B. Leaf, adaxial side. C. Inflorescence, side view. D. Floral bracts. E. Floral bract and ovary, side view. F. Flattened flower. G, H. Column and lip, side view, with intact (G) and artificially turned down lip (H). I, J. Lip, front view (I) and view from rear (J). K, L. Lip view from above (K) and from below (L). M, N. Lip, side view (M) and lip sagittal section (N). O. Operculum, view from above, from below, and side view. P. Operculum, front view and view from rear. Q. Pollinarium. R. Stipe with viscidium, front and side view. Drawing of L. Averyanov from the specimen AL2233a.