Gastrodia munasinghae Atthanagoda, C. Bandara & Kumar 2023, sp. nov.
Creators: name: Bandara, Champika
name: Atthanagoda, Anusha Gayan
name: Bandara, Nadeesha Lewke
name: Kumar, Pankaj
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Liliopsida
Asparagales
Orchidaceae
Gastrodia
Gastrodia munasinghae

description: Gastrodia munasinghae Atthanagoda, C.Bandara & Kumar sp. nov. (Figs. 1 A–E, 2 & 3)
Type:— SRI LANKA, Sabaragamuwa Province, Ratnapura District, Maliboda –Sri Pada trail, Samanala Nature Reserve, 30 March 2022, AKAG10.2022 (holotype PDA!; isotype PDA!-spirit); Sabaragamuwa Province, Ratnapura District, in a fragmented forest patch near a tea plantation between Panapola–Pothupitiya, 4 April 2022, AKAG11.2022 (paratype PDA!).
Diagnosis:— Gastrodia munasinghae is morphologically allied with G. uraiensis Hsu & Kuo (2010: 244) and G. fontinalis Lin (1987: 129) in having similar rough-surfaced brown coloured perianth tube, petals attached at the tip of junction of lateral sepals, orange winged column, stigma placed towards the base of the column and two rounded callus at the base of the labellum, however, the new species differ in having taller plants in former, 10–18 cm tall (vs. 1–4 cm tall plants in G. uraiensis and 7–12 cm tall in G. fontinalis), inflorescence with 4–8 flowers (vs. 1–3(–5) flowers in G. uraiensis and 1–3 flowered in G. fontinalis), labellum 4–4.5 mm long (vs. 6–7 mm long labellum in both G. uraiensis and G. fontinalis) and dull green-blue mesochile and bright orange color epichile in the labellum (vs. reddish brown coloration in G. uraiensis and G. fontialis). G. munasinghae can be also distinguished from G. bambu Metusala (2017: 212) in having 12 mm long, up to 10 mm wide, widely opening smaller flowers (not widely opening, 17 – 20 mm long and 14 – 16 mm wide larger flowers in latter), ovate-orbicular, 4–4.5 mm long and 3–3.2 mm wide labellum (oblonglanceolate, 10 – 12 mm long × 3.5 – 4 mm wide labellum in latter) and erect, 5–5.5 mm long, 2.8–3 mm wide column (slightly arcuate, 10 – 12 mm long, 2 – 2.5 mm wide column in latter).
Terrestrial holomycoheterotrophic herbs, 10–18 cm tall. Rhizome tuberous, fusiform or cylindrical, 7–13 × 1.2–2.3 cm, plagiotropic, hairy, membranous triangular scales emerging from the nodes. Raceme erect, peduncle 8–13 cm long, glabrous, pale brown in color, with 3–5 membranous semi-transparent sheaths; sheaths tubular, 4–5.5 mm long. Inflorescence erect with 4–8 flowers, rachis ca. 4–6 cm long. Floral bracts triangular, 5–6 mm, acute, dark greyish brown to dark brown in color, membranous, margin slightly lacerate, base surrounding the pedicel. Pedicel orange-brown, ca. 8–11 mm long, 2.5–3.2 wide. Flowers resupinate, sepals and petals fused to form perianth tube, widely opening; apical part free, forming a five-lobed front; ridges 4; 12 mm long, up to 10 mm wide, outer surface greyish brown, verrucose, inner surface dark brown in color with dull orange-brown under lateral sepals and greyish under dorsal sepal and petals; lobe of dorsal sepal triangularly ovate, 6 × 4.5 mm, obtuse, slightly convex, brown, margins entire; lobes of lateral sepals triangularly ovate, 4.5 × 5 mm, brown, margins entire; petal lobes ovate-elliptic, smaller than sepal lobes, 3.5 × 2 mm, pale brown; labellum adnate to the foot of column, ovate-orbicular, 4–4.5 × 3–3.2 mm, hypochile short, ca. 1 mm long, broader at the base and narrowing towards the epichile, inflated, with 2 globose calli at the base, callus 0.5–0.8 mm in diameter, pale orange-yellow colored with dark brown shiny surface; epichile ovate, 3.5–3.8 mm long, 3.1–3.3 mm wide, obtuse, bright orange at the apex, pale yellowish green along the middle and pale brownish-orange at the base, slightly tapering toward apex with a pair of lamellae or short ridge on the upper surface, longitudinally channeled underneath of the lip from base to the tip. Column erect, 5–5.5 × 2.8–3 mm, whitishcream with grey-brown colored at base, slightly extended into a short foot, ca. 1.5 mm long, 2–2.5 mm wide; stelidia falcate, 2.5–3 × 0.5–0.6 mm, apex acute, extended slightly beyond the anther cap, red-orange; rostellum prominent; stigma located towards the lower half of the column on a raised but slightly inclined and convex platform. Anther cap cucullate, ca. 1.5 mm in diameter. Pollinia 2, clavate, ca. 1.2 mm long. Ovary obconical, 3.5–4 mm long, ca. 2.5 mm wide, dark brown, verrucose, ribbed. Capsule erect, fusiform, verruculose, ca. 2.3–2.7 cm long, 4.5–5 mm wide, on a longer stalk of variable length,> 2 cm long, pale orang-brown with darker stripes, borne on an elongated pedicel, up to 18–32 cm long, pale brown, slender and terete.
Phenology:— Flowering and fruiting individuals were observed from early January to April in different subpopulations. The subpopulations in Samanala Nature Reserve begin flowering from January to April and the population in lowland wet zone flowering only in March and April.
Etymology:— The specific epithet honors Mrs. Liliyan Chandralatha Munasinghe, the second author’s mother for her unconditional love, support and encouragement.
Distribution:— Gastrodia munasinghae is endemic to Sri Lanka and thus far known from the sub-montane forests in Maliboda–Sri Pada trail and Kuruwita–Eratne–Sri Pada trail in Samanala Nature Reserve, Central Highlands of Sri Lanka and fragmented forest patch of the lowland rain forests bordering to a tea plantation near Pothupitiya in Ratnapura District (Fig. 7).
Habitat and ecology:— This species grows under the shade of Strobilanthes lupulina, Strobilanthes zeylanica (Acanthaceae) and Ochlandra stridula (Poaceae) species in the lowland forests between 400 and 715 m a.s.l and between 600 and 1000 m a.s.l in foothills of the Adam’s Peak on humus-rich decaying leaf litter. The rhizomes are buried up to 2–4 inches deep in the ground. Other notable Orchidaceae members sharing the same habitat were Sirhookera lanceolata, Zeuxine regia, Anoectochilus sp., Habenaria crinifera, and Oberonia sp. at Pothupitiya and Zeuxine reginasilvae from Maliboda–Sri Pada trail.
Taxonomic notes:— Gastrodia munasinghae morphologically close resembles G. uraiensis, G. fontinalis and G. bambu but, is readily distinguished in having 10–18 cm tall plant habit; 4–8 flowered inflorescence; 12 mm long and 10 mm wide flowers; ovate-orbicular, 4–4.5 mm long and 3–3.2 mm wide, dull green-blue colored mesochile and bright orange colored epichile in the labellum and erect, 5–5.5 mm long, 2.8–3 mm wide column. The brown-colored Gastrodia species are morphologically similar to each other on their external appearances but, all species have unique morphological characters and distribution ranges. Clements and Jones (2019), combined this group of brown color Gastrodia species s.l. to the genus Demorchis M.A.Clem. & D.L.Jones. However, this genus is not accepted and synonymized under the genus Gastrodia (Jones & Clements 2004, Clements & Jones 2019, POWO 2023).
Conservation status:— Gastrodia munasinghae grows in sub-montane and lowland forests in Sabaragamuwa Province with a small population size of 8 mature individuals found during the first visit in Eratne–Sri Pada trail in Samanala Nature Reserve far back in 2005. Unfortunately, this species was never seen again at this locality after repeated visits until 2022. Later, another subpopulation was discovered in 2012 in Maliboda–Sri Pada trail and the number of mature individuals varied in 2012, 2016, 2020 and 2022 with 6, 3, 8 and 4 respectively (Fig. 8). Recently, another subpopulation has been discovered in 2022 at a fragmented forest patch adjacent to a tea plantation along Panapola– Pothupitiya road, containing 11 flowering individuals. At the first two sites, the habitat is heavily disturbed due to the frequent clearance of the existing pilgrim trails of the Sri Pada (Adam’s Peak) and pollution. The other subpopulation in Pothupitiya is also facing the risk of extinction due to anthropogenic disturbances and land use changes. Area of Occupancy (AOO) and the Extent of Occurrence (EOO) was estimated using GeoCAT (Bachman et al. 2011) as 12 km 2 and ~ 32 km 2 respectively. These mycoheterotrophic species are extremely habitat specific and are susceptible to even minor disturbance. Hence, based on the available data, three sites are considered as three locations. As such the total number of mature individuals encountered so far is 27, however, as these mycoheterotrophic species sometimes remain dormant with underground tubers, hence we optimistically estimate total number of mature individuals to be less than 50. Accordingly, the species is assessed as Critically Endangered (CR D), based on current data and following IUCN guidelines (IUCN 2022).
description: Published as part of Bandara, Champika, Atthanagoda, Anusha Gayan, Bandara, Nadeesha Lewke & Kumar, Pankaj, 2023, The study of the tribe Gastrodieae (Orchidaceae, Epidendroideae) in Sri Lanka I: two new species of Gastrodia, pp. 115-130 in Phytotaxa 622 (2) on pages 116-117, DOI: 10.11646/phytotaxa.622.2.2, http://zenodo.org/record/10084582