Coelogyne phitamii Aver. & K.S.Nguyen, 2023

Averyanov, Leonid V., Nguyen, Van Canh, Truong, Ba Vuong, Nguyen, Khang Sinh, Nguyen, Cuong Huu, Maisak, Tatiana V., Doan, Nga Thi, Nguyen, Tuan Hoang, Pham, Van The, Dat, Pham Thi Thanh, Thai, Tran Huy, Nguyen, Van Khuong & Trinh, Ngoc Bon, 2023, New orchids in the flora of Vietnam VI (Orchidaceae, tribes Arethuseae, Cymbidieae, Diurideae, Epidendreae, Vandeae, and Vanilleae), Phytotaxa 597 (2), pp. 87-110 : 89-93

Coelogyne phitamii Aver. & K.S.Nguyen , sp. nov. ( Fig. 1 )

Type: — VIETNAM, Son La Province, Thuan Chau District, Chieng Pha Commune, remnants of primary evergreen broad-leaved forest on limestone mountain, lithophytic and epiphytic perennial creeping herb, flower greenish-yellowish white, adaxially lip dark brownish-red, 9 September 2022, Nguyen Sinh Khang , Lo Trung Van , AL 1593 (holotype LE01170123 https://herbariumle. ru/?t=occ&id=162710, isotype HN, LE01170118 https://herbariumle.ru/?t=occ&id=162682, authentic photos LE01123558 https:// en.herbariumle.ru/?t=occ&id=142722) .

Paratype: — VIETNAM, the border between Dien Bien (Tuan Giao District, Toa Tinh Municipality) and Son La Province ( Thuan Chau District , Phong Lai Municipality ), 15August 2022, Nguyen Phi Tam, AL 1592 ( LE01170155 https://herbariumle.ru/?t=occ&id=162879, authentic photos LE01123556 https://en.herbariumle.ru/?t=occ&id=142720) .

Etymology: —The species name honors its discoverer, an orchid enthusiast named Mr. Nguyen Phi Tam.

Herb lithophytic and epiphytic, perennial, with creeping plagiotropic rhizome and ascending or erect pseudobulbs. Rhizome semiwoody, 25–35 cm long, (2)2.5–3(3.5) mm in diameter, covered by 7–9 pale yellowish gray bract remnants, with a few rigid, pale brownish roots arising from nodes and internodes. Pseudobulbs 2-leaved, green, distant on (3) 4–7 cm, narrowly cylindrical, (2.5)3–4(4.5) cm long, (5.5)6–8(9) mm in diameter, young with 1–2 pale yellowish grey, papyraceous bracts at the base. Leaves glossy green, apical, subopposite, subsessile, leathery, narrowly elliptic, acute, (6)7–9(10) cm long, (2.5)2.8–3(3.2) cm wide. Inflorescence hysteranthous, arising from the apex of mature pseudobulb, erect, normally with 2 flowers; inflorescence axis green, (2)2.5–3(3.5) cm long, at base enveloped by 2–3 pale yellowish, papyraceous sterile bracts; floral bracts pale yellowish, papyraceous, narrowly elliptic to narrowly ovate, acute, (1.2)1.4–2.2(2.4) cm long, (2)2.2–5(6) mm wide, early caducous. Pedicel and ovary pale green, (4)4.5–5(5.5) mm long, ovary 1.6–2.2 mm in diameter, broadening distally, shallowly ribbed. Flowers widely opening, (1.8)2–2.5(2.8) cm across; sepals and petals light yellowish; lip light yellowish with chestnut brown center and chestnut brown keels; column very light yellowish green to almost white with brown apex; anther cap orange. Sepals subsimilar, spreading, narrowly ovate, (1.5)1.6–1.8(2) cm long, 6–8 mm wide, acute, and shortly apiculate; lateral sepals slightly oblique. Petals linear, spreading or slightly recurved, acute, as long as sepals, 1–1.2 mm wide. Lip broadly ovate in outline, (1.5)1.6–1.8(2) cm long, 1.4–1.6 mm wide, 3-lobed; lateral lobes erect, obscurely triangular, 4–5 mm long and wide, with entire margin, ciliate at apex; median lobe half circular, (7)8(9) mm long, (0.9)1–1.2(1.3) cm wide, fimbriate along margin; median lobe with 6 undulate keels, two inner extending from base to the apical part of the median lobe, the other much shorter. Column stout, slightly curved, (1.1)1.2–1.3(1.4) cm tall, in apical half with broad, forward directed, rounded wings; column with flattened wings (4)5(6) mm wide; column apex round, irregularly denticulate; stigma in form of a half circular hollow. Anther cup hemispheric, 2–2.2 mm across, with a broad, truncate beak at the front and with prominent boss at the apex. Pollinia 2, lens-shaped, dull yellow, with a small amorphous viscidium. Fruits unknown.

Ecology and phenology:—Perennial epiphytic and lithophytic creeping herb. Primary and secondary broad-leaved evergreen forests on limestone. Occasional. Flowers in August–September.

Distribution:— Vietnam, provinces Dien Bien (Tuan Giao District), and Son La (Thuan Chau District).

Conservation status:—Two species populations were discovered in NW Vietnam, in a small area along the border of Son La (Thuan Chau District) and Dien Bien provinces (Tuan Giao District), a total area of about 2700 km ². Taking into consideration the vast deforestation in this area and the occurrence of both discovered populations in highly disturbed remnants of primary forest, the case meets the following conditions of IUCN Red List criteria (2022): the extent of occurrence (EOO) less than 5000 km 2, the area of occupancy (AOO) less than 500 km 2, only two existing, severely fragmented populations, the continuing decline observed, estimated, inferred and projected in the extent of occurrence, the area of occupancy, the quality of habitat; and the number of mature individuals. Following these criteria, the status of the species may be preliminarily estimated as Endangered, EN (B1a,b(i-iii,v), B2a,b(i-iii,v).

Notes:—New species belongs to the Coelogyne sect. Fuliginosae Pfitzer & Kraenzlin in Engler (1907: 33) and may be close to C. fimbriata Lindley (1825 : tab. 868) in plant habit and flower lip shape. However, the new species differs from all species of the section in the presence of five distinct high keels on the medial lip lobe. In comparison, all other species of the section bear 2 keels on the lip median lobe ( Pelser et al. 2000, Clayton 2002), rarely with 1–2 short, additional, highly reduced lamellae on the sides of well-developed keels ( Seidenfaden 1975).

Coelogyne suaveolens (Lindl.) Hooker (1890: 832) , Seidenfaden (1975: 52, fig. 18), Pearce & Cribb (2002: 338), Clayton (2002: 204), Chen et al. (2009: 323), Zhou et al. (2016: 34), Kumar et al. (2018: 65), Ormerod et al. (2021: 74) . ( Fig. 2 )

≡ Pholidota suaveolens Lindley (1856: 372) . Type :— INDIA. 19 May 1856, cult. Bishop of Winchester s.n. (lectotype K000079285 , designated here) .

Ecology and phenology:—Epiphyte on tall mossy trees, commonly along streams. Primary and secondary evergreen broad-leaved forests on sandstone at an elevation of 500–700 m a.s.l. (and probably higher). Very rare. Flowers in April–June.

Distribution:— Vietnam, Dien Bien Province (Muong Nhe District). NE India, Myanmar, SW China (Yunnan), Thailand, Laos.

Conservation status:—The conservation status of this species in all area of its distribution up to now has not been evaluated (NE). In Vietnam, only one locality has been documented despite special regional fieldwork. Taking into consideration the almost total deforestation in this area and following the formal Red List IUCN (2022) criteria, the species meets in Vietnam the following conditions: A2a,c; B1a,b(i-iii,v)+2a,b(i-iii,v); C1+2(i,ii); D1; observed population reduction for 10 years or 3 generation ≥ 80% are not reversible (A2), based on direct observation (a) and observed decline of the area of occupancy, extent of occurrence and habitat quality (c); the area of occurrence <100 km ² (B1) and the area of occupancy <10 km ² (B2), with 1 known population (a) and continuing observed decline of extent of occurrence (bi); the area of occupancy (bii); area, quality of habitat (biii); the number of mature individuals (bv); the number of mature individuals <250, observed, estimated or projected continuing decline in 25% in 3 years or 1 generation (C1) and observed, estimated, projected or inferred continuing decline when the number of mature individuals in each subpopulation (C2(i)) ≤ 50 and % of mature individuals in one subpopulation = 90–100% (C2(ii)); the number of mature individuals <50 (D), which identifies the species as nationally Critically Endangered (CR).

Notes:—Field observations identify this species as a very rare plant known only from extreme NW Vietnam in a small area close to the Vietnam –Laotian border. Habit and floral morphology fit well with a detailed description of Laos plants published earlier ( Kumar et al. 2018). However, the flowers of Vietnamese plants are somewhat smaller (fig. 2).

Studied specimens:— VIETNAM, Dien Bien Province, Muong Nhe District, Muong Nhe Natural Reserve, Leng Su Sin Municipality , A Suoi Voi Village around point about N 22º20´27´´ E102º21´29´´ secondary evergreen broad-leaved lowland and submontane forest on mountain slopes composed with sandstone at an elevations of 500–700 m a.s.l., creeping epiphyte on a mossy tree along a stream, flower white, lip with a yellow spot on the disk, not common, 17 May 2022, L. Averyanov, Tran Huy Thai, Khang Sinh Nguyen, T. Maisak, VR 1705 ( LE01168995 https:// en.herbariumle.ru/?t=occ&id=140466; analytical photos LE01123261 https://en.herbariumle.ru/?t=occ&id=137034) .

Otochilus lancilabius Seidenfaden (1976: 13 , fig. 11, 1986: 94, fig. 53, 1992: 121), Pearce & Cribb (2002: 327, fig. 82, pl. 15), Schuiteman et al. (2008: 301), Chen et al. (2009: 340), Rokaya et al. (2013: 539), Jalal & Jayanthi (2015: 37), Zhou et al. (2016: 100), Ormerod et al. (2021: 179) . Type: — INDIA. Sikkim Himalaya, Otochilus porrecta Lindl. , 6000 ft. Oct.-Dec. 1892 [Oct.-Dec. 1893 wrong?] R. Pantling 26 (lectotype K000387921 designated here, isolectotypes HUH 00287633, LE01170187, P00403233). ( Figs. 3 A–C )

≡ Coelogyne lancilabia (Seidenfaden) R. Rice (2019: 173) .

Ecology and phenology:—Epiphyte on tall mossy trees. Primary and secondary evergreen broad-leaved, mixeg, and coniferous forests on any kind of parental rocks at an elevation of 1000–2200 m a.s.l. Common and locally abundant. Flowers in October–December.

Distribution:— VIETNAM, provinces Cao Bang, Hoa Binh, Lai Chau, Lao Cai, Nghe An, and Son La. Bhutan, Nepal, NE India, Myanmar, SW China, Laos.

Conservation status:—According to data from available collections and our field observations, this species is still common in many locations in Vietnam. However, its populations exhibit a clear tendency to decrease due to deforestation and the destruction of habitats in most areas of the country. Due to currently available data, the conservation status of this species in Vietnam may be estimated as nationally Near Threatened (NT).

Notes:—Gunnar Seidenfaden, under species description, indicated as a type the specimen “ Pantling No. 26 ” housed at K ( Seidenfaden 1976, 1986). Meanwhile, four available herbarium specimens marked as “ Pantling No. 26 ” have a bit different label data listed here in chronological order of collecting date as follows: “ Sikkim Himalaya, Otochilus porrecta Lindl. Common. Sikkim, 6000 ft., Oct.-Dec. 1892, R. Pantling 26 ” (HUH 00287633 and P00403233); “ Sikkim Himalaya, Otochilus porrecta Lindl. Common. Sikkim, 6000 ft., Oct.- Jan. 1892, R. Pantling 26 ” (LE01170187 https://en.herbariumle.ru/?t=occ&id=162386); “ Sikkim Himalaya, Otochilus porrecta Lindl. , 6000 ft., Oct.-Dec., 1893 R. Pantling 26 (K000387921). Most likely, the date discrepancy was due to a manual writing error, and all herbarium specimens represent a single collection, as was indicated later in the assessment of Sikkimese orchids ( King & Pantling 1898). Considering the indication by G. Seidenfaden (1986) of the specimen housed at K as a type, we accept it as a lectotype, and other specimens “ Pantling No 26 ” are treated here as isolectotypes.

Studied specimens:— VIETNAM, numerous studied specimens of this species from Vietnam are available in the Herbarium LE database and are accessible by following the link: https://en.herbariumle.ru/?t=occ&s= Otochilus %20lancilabius&f=%5Ball%5D.

Figures

FIGURE 1. Coelogyne phitamii Aver. & K.S.Nguyen, sp. nov. A. Flattened flowering plant. B. Intact inflorescence. C. Intact flowers, frontal view. D. Flower bud, side view. E. Opening flower, side view. F. Inflorescence and floral bracts. G. Flattened sepals, petals, lip, column, and anther cap. H. Lip, adaxial surface. I. Lip base. J. Column, frontal view. K. Column, view from different sides. L. Column apex, with, and without anther cap. M. Anther cap, view from different sides. N. Pollinarium and pollinia.All photos were made from plant used for the type preparation AL 1593 by Khang Sinh Nguyen, with photo correction and design by L. Averyanov and T. Maisak.

FIGURE 2. Coelogyne suaveolens (Lindl.) Hook.f. A, B. Flowering plant in nature. C. Intact flowers, frontal view. D. Flattened plant, fruits and inflorescences. E. Flattened inflorescence. F. Individual flower, frontal view, sepals and petals removed. G. Ovary, column and lip, side views. H. Flattened sepals and petals. I. Flattened lip, adaxial surface. J. Flattened lip, abaxial surface. K. Keels on epichile. L. Pedicel, ovary, anther cap and, column, view from different sides. M. Column, frontal view. N. Mature fruits. All photos were made from plant used for the preparation of the specimen Averyanov et al., VR 1705 by L. Averyanov, with photo correction and design by L. Averyanov and T. Maisak.

FIGURE 3. Otochilus lancilabius Seidenf. A. Flowering plant in nature (specimen H.T. Nguyen et al., HAL 9607). B, C. Intact flowers. Frontal and half-side view (specimen H.T. Nguyen et al., HAL 10262). Cymbidium cochleare Lind. D. Flowering plant in nature.E. Portion and inflorescence. F. Intact flower, side view (specimen H.T. Nguyen et al., HAL 9950). C. goeringii (Rchb.f.) Rchb.f. G. Flowering plant in cultivation. H. Intact flower, frontal view. I. Details of column and lip, frontal view (specimen L. Averyanov et al., AL 1901). All photos by L. Averyanov, with photo correction and design by L. Averyanov and T. Maisak.