Tainia epiphytica S. Sarkar, Agrawala, S. Chakraborty, D. Maity & Odyuo, 2023

Sarkar, Shuvadip, Agrawala, Dinesh Kumar, Chakraborty, Sayak, Maity, Debabrata & Odyuo, Nripemo, 2023, Tainia epiphytica sp. nov. (Orchidaceae), a new species from North East India, Phytotaxa 578 (2), pp. 180-188 : 181-183

Tainia epiphytica S. Sarkar, Agrawala, S. Chakraborty, D. Maity & Odyuo sp. nov. ( Fig. 1 ).

Tainia dunnii auct. non Rolfe (1908: 368): Turner, Orch. Monogr. 6 (1992: 77, fig. 43), pro parte; Averyanov, Turczaninowia 16 (1) (2013: 48, fig. 19 h, i; 24 a, b).

Diagnosis:—The new species differs from Tainia latifolia by its epiphytic habit, and smaller plant size (27.5‒36.4 cm) [vs terrestrial with larger plant (75‒110 cm)]; flowers yellowish suffused with purplish-brown strips towards margins [vs brownish with purplish brown veins]; pedicel and ovary 6.9‒16.7 mm long, greenish to purplish [vs 8‒9 mm long, dark purple]; sepals 9‒11 mm long [vs 11‒14 mm long]; labellum with 3 elevated, longitudinal lamellae converging towards apex; originating from base of labellum and extending near to the apex of the apical lobe, median one narrow towards base and thickened and undulated towards apex; lateral two are shorter than median one, narrow towards base, thickened and elevated at middle and gradually flattened and undulated towards apex [vs three lamellae elevated from base to apex, lateral ones more elevated at middle]; obscure columnar wings [vs broad and elevated wings towards apex]; anther with two greenish dome shaped appendages towards apex [vs purple lateral crest].

Type:— INDIA. Mizoram: Aizwal, on the way to Reiek Tlang , 1200 m, 23°41’09.62’’ N 92°37’32.67’’ E, 15.03.2021, S . Sarkar & S . Chakraborty 41642 [Holotype CAL (Bar code: CAL0000214625 )]; [Isotype: CAL (Bar code: CAL0000214626 )]; S . Chakraborty & S . Sarkar 41588 [Paratype CAL (Bar code: CAL0000214627 )] .

Description: —Epiphytic, sympodial herb, 27.5‒36.4 cm long. Rhizome 2‒2.5 cm long, slender, creeping with 2‒3 internodes covered with fibrous sheaths which disintegrate on maturity. Roots 3‒4 mm in diam., fleshy, arising from the nodal regions of the rhizome. Pseudobulbs 4‒5 × 0.4‒0.8 cm, conical or fusiform, oblique, shrivelled and deeply grooved on maturity, enveloped by fibrous sheaths on maturity. Leaf solitary, 17‒23.1 × 2.8‒5.5 cm, apical, elliptic, entire, acuminate, with 3 main veins, tapering towards base to form a 2‒4.2 cm long, slender, channelled, green petiole which is seemingly articulated with the apex of pseudobulbs but without an abscission layer, so that the leaves are not deciduous. Inflorescence 27.5‒36.4 cm long, racemose, erect, arising laterally from the base of the mature pseudobulb; peduncle erect, slender, glabrous, with 2, 3.5‒4.3 cm long tubular, entire, acute, membranous, stem clasping bracts and 3‒4 internodes towards base; rachis 10.5‒15.5 cm long with lax to sub densely arranged 11‒16 flowers. Floral bracts 5‒9 × 1‒1.24 mm, oblong, acuminate, pale brown, persistent, 3-veined. Flowers 1.73‒2.2 cm long, 1.18‒1.23 cm in diam., widely spreading; sepals and petals yellowish suffused with purplish-brown stripes along margins, labellum yellowish with purple brown side lobes, disc with two lateral, purplish-brown suffused with yellow lamellae and a median one which is yellow in the middle part and brownish at both ends, column yellow marked with purplish-brown along margin and with blotches in the middle part, anther cap yellowish with two greenish dome shaped appendages towards apex. Pedicel and ovary 6.9‒16.7 mm long, clavate, ridged, glabrous, greenish to purplish. Sepals and petals subsimilar, free, deflexed at apex; dorsal sepal c. 1.05‒1.1 × 0.1 cm, linear‒oblong, entire, acute; lateral sepals 0.95‒ 1.1 × 0.1‒0.15 cm, weakly falcate, slightly oblique at base. Petals 1.1‒1.15 × 0.15‒0.17 cm, oblong, slightly oblique, entire, acute. Labellum 0.75‒0.9 × 0.4 cm, 3-lobed, fleshy, immovable, base attached to the base of column; lateral lobes 0.45‒0.5 × 0.1‒0.15 cm, erect, obliquely triangular, auriculate, entire, rounded; mid-lobe 0.15‒0.2 × 0.25‒0.3 cm, broadly obovate to suborbicular, entire, slightly mucronate, slightly decurved towards apex; disc with 3 elevated, longitudinal lamellae converging towards apex; originating from base of labellum and extending near to the apex of the mid-lobe; median one c. 0.7 cm long, narrow towards base and thickened and undulated towards apex; lateral two shorter than median one, 0.65‒0.66 cm long, narrow towards base, thickened and elevated at middle and gradually flattened and undulated towards apex. Column 0.65‒0.7 cm long, slender, slightly curved, columnar wings hardly developed; column-foot 0.1‒0.11 cm long. Anther 0.5‒1 × 1‒1.2 mm, 2-loculate, orbicular with two globular appendages towards apex. Pollinia 8, 4 in 2 groups, subequal, 0.5‒0.55 × 0.3‒0.4 mm, obovoid. Rostellum erect, ligulate. Stigmatic cavity 0.1 mm in diam., suborbicular. Capsules 2‒2.6 cm long, clavate, ribbed, long pedicellate.

Phenology: —Flowering observed in March and fruiting observed in April (under cultivation).

Habitat: —Epiphytic, growing on moss-covered tree trunks in subtropical evergreen forests dominated by Castanopsis purpurella , Duabanga grandiflora , Myristica sp. , Podocarpus sp. , Quercus semiserrata , Schima wallichii , etc. at 1200‒1600 m above mean sea level, associated with Anoectochilus roxburghii , Ania viridifusca , Cymbidium lancifolium , Dendrobium sp. , Phaius mishmensis , Zeuxine sp. etc.

Distribution: — India (Mizoram and Nagaland); Laos & Vietnam [see notes below].

Etymology: —The new species is named for its epiphytic habit, which is unique in the genus Tainia .

Additional specimen examined: —Nagaland: Mon, Tobu, 1600 m, 2016, Odyuo & Roy 138322 (cult. ASSAM). Vietnam: Dien Bien Province, Muong Cha District, Mua Ngai Municipality , 1150‒1250 m, 18 th December 2010 , L.Averyanov, P.K.Loc, P.V.The, N.T.Vinh. CPC 1088e (LE‒Image!). (Flowered under cultivation on 28 th February 2012).

Taxonomic Notes:

Averyanov (2013: 48) had identified a specimen from Dien Bien, Muong Cha of Vietnam under Tainia dunnii and also provided a photograph. This specimen differs from the true Tainia dunnii in being a much smaller plant with different pseudobulbs which are cylindrical to narrowly ovoid; leaves 12‒20 (30) × (1.5) 3‒7, elliptic; labellum with 3 subsimilar low, papillose keels (vs taller plants with hardly defined, narrowly cylindrical pseudobulbs; leaves 13‒ 18 × 2‒2.5 cm, lanceolate; labellum with 2 keels on disc). Averyanov did not mention about the epiphytic habit of his collection from Vietnam but the photographs clearly depicted its epiphytic nature (https://en.herbariumle.ru/?t=occ&id=82599&rid=image_0163434). [Photographs with Bar code no: LE 01122129].

Similar specimen was also observed by Dr. Pankaj Kumar (Pers. Comm.) from Laos [ LAOS PDR. Xiengkhuang Province, Mueang Mok, Pha Deng , 17 th January 2020, G. Fischer, P. Kumar, S. Bouamanivong & T. Phaxaysombath HNL-KFBG 1538 ( HNL)] which confirms the characters depicted in our new species. Major portion of the description and illustration of Tainia dunnii included by Turner (1992: 77) also clearly resemble our new species .

Red list Assessment as per IUCN guidelines ( IUCN, 2012a; 2012b; 2019):

The global distribution of Tainia epiphytica is India, Laos and Vietnam. Until now, this species is known far from 4 sub-populations distributed in India (Mizoram and Nagaland), Laos and Vietnam. The Extent of Occurrence (EOO) could be calculated as 323390.660 km 2 which is beyond the threshold of threatened categories under the Criteria B1 of IUCN. However, the Area of Occupancy (AOO) 16 km 2 [grid size of 2× 2 km ( Fig. 2 )] meets the criteria B2 for Endangered category. 30‒40 mature individuals were observed in each sub populations from India. This species can be considered as ‘Severely fragmented’ on the basis of the disjunct nature of its distribution and also the number of subpopulation (four) meet the sub criteria B2a of IUCN for Endangered category. All the recorded habitat qualities are declining due to developmental activities, expansion of agricultural fields and many other anthropogenic activities including tourism. Being an epiphyte, its survival depends on the host species. The pollination and seed germination is vector dependent and vegetative reproduction is not so effective. In the view of the above, the threat status of this species is assessed as Endangered [EN B2ab(iii)] in global perspective ( IUCN 2019). Germplasm is maintained in BSI, Eastern Regional Centre, Shillong ( Fig. 4B ) and BSI, Sikkim Himalayan Regional Centre, Gangtok campus for ex-situ conservation. More intense floristic survey and habitat management is recommended for its conservation.

Figures

FIGURE 1.A. Habit; B. Inflorescence; C. Flower with pedicel and ovary along with bract; D. Bract; E. Flower (top view); F. Flower (side view); G. Dissected floral parts (i.e. dorsal sepal, lateral sepals, petals, labellum with column); H. Labellum; I. Labellum with column; J. Column (side view); K. Anther; L. Pollinia with anther cap.

FIGURE 2. Distribution of Tainia epiphytica in World with Area of Occupancy and Extent of Occurrence. [Map created in GeoCAT platform http://geocat.kew.org.].

FIGURE 4. A. Habit photo of Tainia epiphytica from Mizoram; B. Ex-situ conservation of Tainia epiphytica collected from Nagaland and maintained in Botanical Survey of India, Eastern Regional Centre campus.