Trichoglottis quadriga Atthan., C.Bandara, Peiris & Kumar, 2023

Bandara, Champika, Atthanagoda, Anusha Gayan, Peiris, Gayan Prasanga, Jayasundara, Ramitha, Ranasinghe, Bhanuka, Kumara, Udayanga Nuwan, Aberathne, Nimantha, Hettiarachchi, Dushantha, Dissanayake, Malith, Karunathilake, Thimira, Bandara, Niwahal Vimukthi, Fernando, Oshan Dewmith, Wijesundara, Chandra Bandara, Bandara, Nadeesha Lewke & Kumar, Pankaj, 2023, Trichoglottis quadriga (Orchidaceae: Epidendroideae: Vandeae: Aeridinae), a new species from Central Highlands of Sri Lanka, Phytotaxa 609 (4), pp. 265-272 : 266-270

Trichoglottis quadriga Atthan., C.Bandara, Peiris & Kumar sp. nov. ( Figs. 1–3 )

TYPE: SRI LANKA. Sabaragamuwa Province, Ratnapura District, Samanala Nature Reserve, Mukkuwatte –Sri Pada Trail, 1145 m a.s.l., 23 March 2022, AKAG 15.2022 (holotype-PDA!) ; AKAG 16.2022 (topotype PDA!-spirit) .

Diagnosis: Trichoglottis quadriga is morphologically very similar to a Vietnamese endemic, T. canhii , but it can be easily distinguished from the latter in having leaf apex bi-lobed with acute lobules (vs. leaf apex bi-lobed with rounded lobules); 4-flowered racemes (vs. 5–12-flowered racemes); longer terete spur, more than half the length of the pedicel and ovary, 3.2 mm long, 1.2 mm wide, with bi-lobed apex (vs. shorter, broadly conical spur, less than half of length of pedicel and ovary, 1.4–1.8 mm long, 1.2–1.5 mm wide, with round apex); larger labellum (5.5 mm long and 3.5 mm wide) (vs. shorter labellum, 3.8–4.0 mm long, 1.8–2.0 mm wide), with longer side lobes; rostellum strongly beaked with the beak arching upwards (vs. rostellum feebly beaked); lobes of pollinia less than half the length of the caudicle and viscidium (vs. lobes of pollinia more than half the length of stipe and viscidium).

Epiphytic monopodial herb. Roots numerous, terete, 3.0‒ 16.5 cm long, 0.8‒1.2 mm in diameter, flexuose, greenish-grey, glabrous, arising from basal part of the stem. Stem unbranched, stout, rigid, 0.7‒2.0 cm long, 0.4‒0.6 cm in diameter, greenish with silvery white velamen; internodes 3.0‒ 4.5 mm long, rarely branched near base. Leaves 3‒7, almost sessile, distichous, narrowly lanceolate to oblanceolate, margins entire and wavy, 4‒8(‒12) cm long, 0.4‒0.7 cm wide, arching, obliquely bi-lobed at the apex, longer lobule 1 mm long, shorter lobule 0.5 mm long, acute, midrib keeled, extended to a pointed setae in between lobules, ca. 0.2‒0.3 mm long. Inflorescence 4-flowered racemes, 1.1‒ 4.6 cm long, arising from stem through the leaf sheaths on internodes. Peduncle stout, terete, rigid, 1.5‒2.0 cm long, 0.9–1.3 mm in diam, greenish; with 2–3 persistent, triangular sterile bracts, 1.0– 1.2 mm long and wide, appressed to the peduncle. Rachis irregularly angled in cross section, 1.0– 1.5 mm in thick. Pedicel and ovary almost cylindric, slightly swollen in upper half, ca. 5.5‒6.0 mm long, curved, glabrous, green when unfertilized. Flowers widely opened, sepals and petals spreading, 9.0‒ 10 mm across, sepals and petals dull-yellow speckled with brown; lip white and spur pale yellow; column base brown and operculum light dull yellowish to almost whitish; pollinia pale yellowish. Floral bracts persistent, triangular, 0.7 mm long, 1 mm broad, acute, concave, dull greenish to light brown. Dorsal sepal oblanceolate, 9.0 mm long, 1.8 mm wide, narrowly obtuse, obtuse, 3-veined. Petals linear-elliptic to linearoblanceolate, 3.5 mm long, 1.6 mm wide, obtuse, 3-veined. Lateral sepals oblique-falcate, 4.3 mm long, 1.7 mm wide, apex rounded, 3-veined. Labellum 5.5 mm long, 3.5 mm wide (length from the base of column to the apex of median lobe), firmly attached to the column, spurred, elongate disc at the base, 3-lobed in the apical half; disc terete, channeled longitudinally on the upper side with slightly winged and raised margin, channel with dense soft hairs inside, leading to the spur; median lobe glabrous, fleshy, almost hexagonal, 3.2 mm long, 2.2 mm wide, margin crenulate indistinctly forming 5-lobules, lobules obtuse, prominent hollow on the ventral surface at the base; side lobes prominent, thumblike, up to ca. 1 mm long, erect and fleshy. Spur terete, 3.2 mm long, 1.2 mm diameter, apex equally bi-lobed, sparsely hairy on the inner margin with a bifid callus arising from the back wall of spur and ending at the throat, ca. 0.5 mm. Column short, 1.5 mm long, 1.2 mm diameter, stout, erect, broadly cylindrical, foot inconspicuous. Rostellum small, bifid, ca. 1.0 mm long, 0.5 mm wide, greenish-brown, extended into a prominent beak, beak arched upwards. Operculum hemispherical, 2 mm long, 1.2–1.4 mm wide, with a prominent beak oriented in parallel above the beak of the rostellum. Anther terminal, 2 loculed, 1.8 mm long, 2.0 mm wide. Pollinia 4, in 2 pairs, each lobe with 2 unequal sized pollinia tightly appressed to each other into a globular structure, 0.3‒0.4 mm in diameter each; stipe clavate, 1.6–1.8 mm long, with each lobe of pollinia attached on the broader side of the stipe; viscidium ovate, ca. 0.15‒0.20 mm long. Ovary and pedicel clavate, 5.3–5.5 mm long. Capsule fusiform or almost clavate, 2.0– 2.5 cm long, 0.6–0.7 cm diameter, dull green, dotted with dark purple spots and streaks, strongly ribbed.

Phenology: Flowering and fruiting observed during November to March.

Etymology: The specific epithet ‘quadriga’ in Latin stands for the word ‘team’ in English, and is used here appreciating the teamwork of young botanists and naturalists in Sri Lanka for describing this new species.

Vernacular name: Samanala cherub orchid.

Distribution: Trichoglottis quadriga is so far known from Mukkuwatte‒Sri Pada trail in Samanala Nature Reserve, Diyawilla, Rassagala, Bambarabotuwa and Pettigala in Sabaragamuwa Province. Endemic to Sri Lanka.

Habitat and ecology: Trichoglottis quadriga grows in montane and sub-montane forests at 900‒1800 m a.s.l. in Central Highlands of Sri Lanka. The new species is a strict canopy-dweller, growing 6‒15 meters above the ground level epiphytic on medium-sized stumps and branches of lianas and trees of Entada rheedei Sprengel [ Fabaceae ], Horsfieldia iryaghedhi (Gaertner) Warburg [ Myristicaceae ], Macaranga peltata (Roxburgh) Müller Argoviensis [ Euphorbiaceae ], Cullenia ceylanica (Gardner) Wight ex K.Schumann [ Malvaceae ], Dipterocarpus glandulosus Thwaites and Shorea gardneri (Thwaites) P.S.Ashton [ Dipterocarpaceae ]. Other Orchidaceae species which sharing the same habitat of this new species are Cylindrolobus lindleyi (Thwaites) Ormerod & C.S.Kumar , Bulbophyllum crassifolium Thwaites ex Trimen , B. elegans Gardner ex Thwaites , Pinalia tricolor (Thwaites) Kuntze and Podochilus sp. .

With respect to sharing of habitat by different species in this genus, Trichoglottis tenera is widespread in the tropical montane and sub-montane forests at Nuwara-Eliya and Maturata (Nuwara-Eliya District, Central Province), Laggala (Matale District, Central Province), Rangala and Hunnasgiriya (Kandy District, Central Province), and Namunukula (Badulla District, Uva Province) ( Jayaweera 1981) 1200 m a.s.l., while, T. longifolia is distributed in sub-montane forests at Aranayaka, (Kegalle District) and Bambarabotuwa, Kuruwita, Palabaddala, Samanala Nature Reserve and adjacent areas of Sinharaja MAB (Man and the Biosphere Reserve) (Ratnapura District) in Sabaragamuwa Province between 910‒1200 m a.s.l. ( Bandara et al. 2022) ( Fig. 4 ). Trichoglottis quadriga and T. longifolia can occur in same habitat but, can be easily identified following the field identification key provided in this manuscript.

Conservation status: Based on the distribution data, the EOO and AOO were estimated as ~ 47 km 2 and 20 km 2 respectively. So far no threat is known to this species except for the anthropogenic pressure in the habitats, which is inferred to cause a depletion in the quality of habitat for the species. With 5 sub-populations, comprising less than 50 mature individuals Trichoglottis quadriga can be assessed depending on its extremely small population size as Critically Endangered (CR: D) following IUCN guidelines ( IUCN 2022).

Additional specimens examined: Trichoglottis tenera : — SRI LANKA. NUWARA ELIYA DISTRICT: Nuwara Eliya , Aug. 1962, Jayaweera 2192 ( PDA!); Hakgala , Mar. 1889, W. Nock s.n. ( PDA!); Punduluoya , Feb. 1973, Cramer 4067 ( US!- US00506216 ); along road Kandy to Nuwara Eliya , May 1978, D.D. Soejarto 4876 ( US!- US00506217 , L!- L1529312 , P!- P00361712 ); BADULLA DISTRICT: Namunukula , Mar. 1907, J.M. Silva s.n. ( PDA!); LOCALITY UNKNOWN: 1829, Macrae 66 ( K!- K000895724 , holotype); Macrae s.n. ( K!- K000974382 ); Macrae s.n. ( K!- K000974383 ); Thwaites C.P.2983 ( PDA!); Walker 118 ( PDA!); 1869, Thwaites C.P.2983 ( P!- P00361710 ); 1854, Thwaites C.P.2983 ( P!- P00361711 ). INDIA. Grands bois à Neddoubitta , Jan. 1841, L. Claude s.n. ( P!- P00361713 ) . Trichoglottis longifolia : — SRI LANKA. KEGALLE DISTRICT: Maligakande , Aranayaka, Apr. 2022, AKAG 29.2022 ( PDA!-spirit); RATNAPURA DISTRICT: Seethagangula , Kuruwita‒Eratne trail , Samanala Nature Reserve , May 2022, AKAG 30.2022 ( PDA!) .

Figures

FIGURE 1. Trichoglottis quadriga Atthan., C.Bandara, Peiris & Kumar sp. nov. A. & B. Plant habit. C. Inflorescence. D. Front view of flower. E. Lateral view of a partially opened flower. F. Capsule. Photographs by Anusha Gayan Atthanagoda.

FIGURE 2. Trichoglottis quadriga Atthan., C.Bandara, Peiris & Kumar sp. nov.A. Plant habit. B. Inflorescence. C. Front view of flower. D. Fronto-lateral view of flower. E. Lateral view of flower. F. & G. Lateral view of labellum and column. H. Sagittal section of column, labellum and spur. I. Floral bract. J. Dorsal sepal. K. Petal. L. Lateral sepal. M. Labellum. N. Capsule. O. Pollinia. P–R. Operculum. S. Leaf apex. T. Dorsal view of spur. Photographs by Anusha Gayan Atthanagoda.

FIGURE 3. Trichoglottis quadriga Atthan., C.Bandara, Peiris & Kumar sp. nov. A. Plant habit. B. Inflorescence. C. Lateral view of flower. D. Front view of flower. E. Bract. F. Dorsal sepal. G. Petals. H. Lateral sepals. I. Labellum. J. Lateral view of labellum, column and spur.K. Sagittal section of column, labellum and spur.L. Dorsal view of spur.M. Leaf apex. N. Capsule. O. Pollinia. P–R. Operculum. Illustration+s by Champika Bandara.

FIGURE 4. The distribution range all species of Trichoglottis in Sri Lanka.