Vietorchis proboscidea Aver., Vuong & V.C.Nguyen, 2023

Averyanov, Leonid V., Nguyen, Van Canh, Vuong, Truong Ba, Nguyen, Khang Sinh, Nuraliev, Maxim S., Nguyen, Cuong Huu, Ormerod, Paul A., Maisak, Tatiana V., Diep, Dinh Quang, Lyskov, Dmitry F. & Nong, Duy Van, 2023, New orchids in the flora of Vietnam VII (Orchidaceae: tribes Cypripedieae, Cranichideae, Orchideae, and Collabieae), Phytotaxa 619 (4), pp. 255-276 : 269-273

Vietorchis proboscidea Aver., Vuong & V.C.Nguyen , sp. nov.

( Fig. 6 )

Diagnosis:—The new species differs from the morphologically closest V. furcata in having a simple, proboscis-like epichile with an entire or obscurely 3-dentate apex.

Type:— VIETNAM. Lam Dong Province: Dam Rong District, Lien Srong Commune, mycoheterotrophic orchid, near the stream in primary broad-leaved forest, 28 April 2023, Truong Ba Vuong , Nguyen Van Canh, BV 1716 (holotype VNM00063991 , photos LE01124200 https://en.herbariumle.ru/?t=occ&id=170352) .

Paratypes:— VIETNAM. Lam Dong Province: Dam Rong District, Lien Srong Commune , mycoheterotrophic orchid, near the stream in primary broad-leaved forest, 28April 2023, Truong Ba Vuong, Nguyen Van Canh BV 1717, BV 1718 ( LE, VNM00063993 ). Photo record studied :— VIETNAM. Lam Dong Province: Dam Rong District , evergreen broad-leaved forest, 24 April 2023, Truong Van Can, Dinh Quang Diep s.n. ( LE01124199 https://en.herbariumle. ru/?t=occ&id=170351) .

Etymology:—The species name refers to the simple, narrowly conoid, proboscis-like epichile.

Description:— Herb terrestrial, achlorophyllous, entirely glabrous. Root tuberoids terete, fleshy, shortly cylindrical, 1.5–2 cm long, (5)6–7(8) mm in diameter. Stem erect, straight or slightly flexuose, (5)6–10(11) cm tall, (2.5)3–3.5(4) mm in diameter, bearing 2–4 white adpressed sterile bract-like leaves and a lax spike 2–4 cm long with (1)2–4 flowers; stem and especially rachis yellow to whitish, often with numerous small dark red spots. Floral bracts membranaceous, white to white with yellowish tint, finely speckled with small purple streaks, narrowly ovate, acuminate, (1.2)1.4–1.8(2) cm long, 6–8 mm wide. Ovary sessile, white to white with yellowish tint, finely speckled with small purple streaks, erect, terete, 3-winged in apical part, (1.4)1.6–2.2(2.5) cm long, (2.5)3–4(4.5) mm in diameter, at base straight and twisted on 180°, in apical half slightly curved and untwisted. Flowers widely opening, bright yellow, 1.6–2 cm across; sepals abaxially with numerous small dark red spots; adaxial side of hypochile, lip callus and column wings dark yellow and usually bearing numerous irregular reddish marks; anther dark violet. Sepals with entire margin; median sepal narrowly ovate, with rounded apex, often slightly cucullate, 6.5‒8 mm long, 4.5‒5 mm wide; lateral sepals obliquely ovate, blunt to obtuse, 9.5‒10.5 mm long, 4.8‒5.2 mm wide, outside slightly keeled. Petals oblique, ovate to broadly ovate, with entire or slightly repand margin, with rounded apex, slightly cucullate, 7‒7.5 mm long, 5‒5.5 mm wide. Lip fleshy, 3-lobed; hypochile concave, 6.5‒7.5 mm long, 5.5–6.5 mm wide (across flattened side lobes); disk at hypochile base with large, glossy, narrowly obovoid callus; side lobes almost semi-circular, concave, 3‒4 mm long and wide; epichile (median lobe) narrowly conoid, proboscis-like, simple, 4‒4.5 mm long, 0.8–1 mm in diameter at base, entire or obscurely 3-dentate at the apex. Column 4.5–5 mm tall (including anther), with large lateral wings; lateral wings fleshy, semi-circular, concave, smooth on both sides, 2 mm long, 1.5 mm wide; auricles at base of anther white, hemispheric, finely verruculose, 1 mm in diameter; rostellum in form of small inconspicuous fold between bases of thecae, supporting viscidium; stigma placed below rostellum, transversally oval, concave; anther finely papillose, erect, obovoid, 2.4–2.6 mm tall, 2.2–2.4 mm wide, with divergent thecae and narrow connective. Pollinarium with 2 pollinia on common viscidium; viscidium naked at least at late anthesis, semi-circular, dark violet; each pollinium 0.8–0.9 mm long, clavate, dark violet, with yellow-orange caudicle. Fruit not seen.

Ecology and phenology:—Terrestrial achlorophyllous ephemeroid herb with tuberoid roots. Evergreen broad-leaved forests on granite at elevation of about 1000 m a.s.l. Very rare. Flowers in April–May.

Distribution:—Endemic to Vietnam (Lam Dong Province: Dam Rong District).

Conservation status:—Only a single location of Vietorchis proboscidea has been discovered, where a few individuals have been observed. The counting of existing sterile individuals in this population is hardly possible due to the holomycotrophic lifestyle of the plant. Vietorchis proboscidea is apparently a strongly habitat-conservationdependent species. Pending comprehensive field studies in the area of its locus classicus, we estimate the conservation status of the species as Data Deficient (DD) according to the criteria proposed by the IUCN Standards and Petitions Committee (2023).

Notes:—The speculative merging of Vietorchis Averyanov & Averyanova (2003: 92) endemic to Vietnam and Silvorchis Smith (1907: 2) known from Vietnam and Java ( Szlachetko et al. 2006, Olędrzyńska et al. 2016, Olędrzyńska & Szlachetko 2021) is based solely on the sketches redrawn from Smith (1907), Averyanov & Averyanova (2003) and Averyanov et al. (2013) without investigation of any actual material. Curiously, this approach was accepted by Chase et al. (2015) and Govaerts et al. (2023) without any relevant justification.

The structure of the pollinarium in Vietorchis remains unclear. According to the current observation on V. proboscidea , two pollinia in an anther have a single common viscidium, and are naked during late anthesis. However, in the flower of V. furcata Aver. & Nuraliev in Averyanov et al. (2013: 253), at the early stage of anthesis, a thin bursicle was observed, which tissue becomes macerated soon, exposing two densely adhered viscidia, which split from each other later ( Averyanov et al. 2013). A similar morphology was observed in V. aurea Averyanov & Averyanova (2003: 95) . Thus, it is likely that V. proboscidea also possesses a bursicle.

Vietorchis proboscidea is surely very close to the sympatric V. furcata , but differs in the absence (vs. presence) of a distinct longitudinal keel on the abaxial side of the lip, smooth (vs. smooth or irregularly verruculose) abaxial surface of the column wings, and, most importantly, in simple, proboscis-like median lobe of the lip with entire or obscurely 3-dentate apex (vs. median lip lobe at apex divided into 2 thin, linear, divergent lobes 1.5 mm long).

Tribe Collabieae (subfamily Epidendroideae )

Calanthe speciosa (Blume) Lindley (1833: 250) , Comber (1990: 93, 2001: 261), Seidenfaden & Wood (1992: 175), Chen et al. (2009: 296), Kurzweil (2010a: 78, 2014: 370), Barretto et al. (2011: 452), Clayton & Cribb (2013: 96), Yokota & Inoue (2016: 269), Zhou et al. (2016: 25). Type:— INDONESIA. In sylvis obscuris montanis Provinciarum Bantam [Banten] et Buitenzorg [Bogor City, West Java Province], Blume s.n. Authentic material indicated to be stored in BO and L ( Kurzweil 2010a: 78, Barretto et al. 2011: 452, Clayton & Cribb 2013: 96) not found and most probably lost; lectotype, proposed here P00353007, isolectotype P00353008).

( Figs. 7A–C )

≡ Amblyglottis speciosa Blume (1825: 371) .

≡ Styloglossum speciosum (Blume) Yukawa & Cribb (2014: 150) .

Ecology and phenology in Vietnam:—Terrestrial herb. Evergreen lowland broad-leaved forests. Rare. Flowers in July–October.

Distribution:— Vietnam (provinces Dak Lak: Ea Kar District; and Khanh Hoa: Cam Lam District). Japan, Southeast China, Thailand, Peninsular Malaysia, Sumatra, Java, Borneo, Sulawesi, Philippines.

Conservation status in Vietnam:—In Vietnam, two verified locations of Calanthe speciosa are known, with a few individuals observed in total. At the same time, the presence of much more locations in the country is highly possible, because the species can be easily misidentified as a widely distributed and very common C. lyroglossa Reichenbach (1878: 53) . Pending large-scale field studies and re-evaluation of existing collections, we estimate the national conservation status of the species as Data Deficient (DD) according to the criteria proposed by the IUCN Standards and Petitions Committee (2023).

Notes:—In the protologue of Amblyglottis speciosa, Blume (1825) listed the known locations in the Javanese provinces of Bantam and Buitenzorg, but has not indicated any particular collections, as well as dates of findings and places of specimen deposition. Barretto et al. (2011) and Clayton & Cribb (2013) believed a specimen Blume s.n. stored in BO to be a holotype of this species (with isotype stored at BO), whereas Kurzweil (2010a) indicated a specimen Blume s.n. at L to be a syntype, but did not mention any specimens from BO. Searches in BO (L.Juswara, pers. comm.) and in L failed to locate potential type material of this species. We have found two specimens collected by Blume in P matching the description and information on distribution included in the protologue. These duplicates were likely transferred to P during exchanges of herbarium collections between the institutions of Leiden and Paris in the 19 th century; they should be treated as syntypes in accordance with Art. 9.6 of ICN ( Turland et al. 2018). We believe these specimens to be the only surviving original material of the species. We selected the specimen with the barcode P00353007 as the lectotype following Arts. 9.3 and 9.11 of ICN ( Turland et al. 2018) as it represents best the species, having a leaf and an inflorescence with numerous flowers. The other specimen at P (P00353008) is an isolectotype; it has a basal part of plant, a leaf and three flowers.

Although C. speciosa was indicated as known from Vietnam by Clayton & Cribb (2013), their record has not been confirmed by specimen citation. Here, we report the specimens collected in Vietnam and undoubtedly belonging to this species for the first time. Although our report is based on two gatherings only, the presence of C. speciosa in other locations in Vietnam is highly probable, given the large general distribution area of the species, and the possibility of its misidentification as the widespread and very common C. lyroglossa or the poorly known C. chevalieri Gagnepain (1931a: 322) described from Hon Ba mountain area (Khanh Hoa Province, southern Vietnam). In addition, several sterile specimens from southern Vietnam housed at P and tentatively identified by Seidenfaden (1992) as C. lyroglossa possibly also represent C. speciosa .

Studied specimens:— VIETNAM. Khanh Hoa Province: Cam Lam District, Hon Ba Nature Reserve , 28 July 2014, Truong Ba Vuong BV 051 ( PSU, photos LE01124222 https://en.herbariumle.ru/?t=occ&id=177154) ; Dak Lak Province: Ea Kar District , 26 September 2021, Dinh Quang Diep s.n. (photos LE01122935 http://en.herbariumle. ru/?t=occ&id=108262) .

Figures

FIGURE 6. Vietorchis proboscidea. A. Flowering plants in situ. B. Flattened flowering plants. C. Tuberous roots. D. Apical half of sterile bract-like leaf. E. Inflorescence. F. Opening flower bud, showing intact apex of the epichile. G. Flower in axil of floral bract, front view. H. Flower, side view. I & J. Flower, front view. K. Column and lip, view from above and front view. L. Column and lip, half-side view. M. Apical part of ovary, column and lip, rear view. N. Apical part of ovary, column, and lip, side view. O. Apical part of ovary, column, and lip, sagittal section. P. Median sepal, abaxial and adaxial side. Q. Lateral sepal, abaxial and adaxial side. R. Petal, abaxial and adaxial side. S & T. Anther, front and side view. U. Pollinarium. Photo A by D.Q.Diep (Truong Van Can, Dinh Quang Diep s.n.), photos B–U by T.B.Vuong (type, Truong Ba Vuong, Nguyen Van Canh BV 1716), photo correction and design by L.Averyanov.

FIGURE 7. Calanthe speciosa. A. Flowering plant. B. Inflorescence. C. Flowers, front view. Photo by D.Q.Diep from the specimen D.Q.Diep s.n. Photo correction and design by L.Averyanov.