Oberonia meegaskumburae Priyadarshana, Wijewardana & Kumar, 2017

Priyadarshana, Tharaka S., Wijewardhane, Ishara H., Atthanagoda, Anusha G., Arangala, Nandun S., Jayasooriya, Asanka & Kumar, Pankaj, 2017, Oberonia meegaskumburae (Orchidaceae: Epidendroideae: Malaxideae), a new species from Sri Lanka, Phytotaxa 302 (3), pp. 259-265 : 260

Oberonia meegaskumburae Priyadarshana, Wijewardana & Kumar , sp. nov.

TYPE:— SRI LANKA. Ratnapura: Adam’s peak, Seethagagula, 31 December 2015, Wijewardana 012SIT (holotype: NWRTC!).

Diagnosis:— Oberonia meegaskumburae is close to O. weragamaensis in having the lateral lobes of the labellum raised above the column and mid-lobe of the labellum divided into three lobules but can be differentiated on the basis of larger flowers (3 mm long in former against 2 mm in latter); longer floral bracts (1.9 mm in former against 1 mm in latter); midlobule of the mid-lobe same size as the side lobules (> 0.2 mm) in the former against a much shorter (<0.1 mm) mid-lobule in the latter; lateral lobe of the labellum slender and terete with a club shaped tip curved to face each other in former against sub-triangular, parallel and inflated in latter.

Description: Plants herbaceous, epiphyte. Roots vermiform. Stem reduced. Leaves 4 to 5, laterally compressed, fleshy, distichous, oblong-ensiform, sub-acute, 5–6 × 0.5 cm. Inflorescence many-flowered, spike, 10 cm long, pendulous. Peduncle terete. Flowers reddish-brown, opening progressively downwards, 3 × 1.5 mm. Floral bracts slightly longer than the dorsal sepals, ovate, acuminate, acute, 1.9 × 0.6 mm. Sepals and petals dissimilar, petals longer than sepals. Dorsal sepal ovate, acuminate, acute, 1.6 × 0.4 mm. Lateral sepals orbicular, rounded, 1 × 0.8mm. Petals ciliate, linear-lanceolate, acuminate, acute, 2.1 × 0.15 mm. Lip 1.4 × 0.5 mm. Lateral lobes succulent, terete, incurved towards club shaped apex, apex facing each other, 1.1 mm long. Mid-lobe trifid, lobules equal sized; lateral lobules sub-triangular, diverging, 0.3 × 0.08 mm; mid-lobule, triangular, 0.25 × 0.08 mm. Column short, 0.5 × 0.4 mm. Operculum broad, 0.2 × 0.15 mm. Pollinia 4, hitching in two pyriform pairs, 0.32 × 0.15 mm, clavate. Larger pollinia obovoid, smaller pollinia disc–shaped. Mature fruit reddish–brown, 3.5 × 1.6 mm (ovary with pedicel). [ FIGURES 1–2 ]

Flowering:— Flowers throughout December to January.

Habitat and Ecology:— Epiphytic plants growing on lichen and moss covered tree trunks; loosely attached on bark, under almost 80% shade. The species was observed only between Seethagagula (6.8223°N, 80.4579°E; 1066 m) and Madahinna Ambalama (6.8195°N, 80.4642°E; 1141 m) at Adam’s peak (Samanala) Nature Reserve , Kuruwita– Erathna footpath, Ratnapura district, Sabaragamuwa province, Sri Lanka. The area belongs to the lowland–wet zone in Sri Lanka ( Ashton et al. 1997). [ FIGURES 3 ]

Conservation status:— At present, Oberonia meegaskumburae sp. nov. is known only from the Adam’s peak, Kuruwita–Erathna footpath. Unsuccessful efforts were made by the authors to find this new species in the adjacent areas. Hence this species has been assessed as Data Deficient (DD; IUCN 2012) and endemic to Sri Lanka.

Etymology:— Species is named after Dr. Madhava Meegaskumbura, a leading taxonomist and herpetologist of Sri Lanka, based at Department of Zoology, University of Peradeniya.

Specimens of other allied taxa examined:— SRI LANKA. Oberonia weragamaensis :— Ratnapura District , Weragama, Jayaweera 2037 ( PDA! - Holotype) ; Oberonia tenuis :— Kandy District , Rangala, Corbet’s Gap, December 1960, Jayaweera 2031 ( PDA!) ; Oberonia walliesilvae :— Kandy District , Rangala, March 1960, Jayaweera 2143 ( PDA! - Holotype) ; Oberonia fornicata :— Kandy District , Rangala, Jayaweera 2025 ( PDA! - Holotype) ; Oberonia claviloba :— Kandy District , Ambagamuwa, December 1969, Jayaweera 2144 ( PDA! - Holotype) ; Oberonia dolabrata :— Kandy District , Corbet’s Gap, April 1960, Jayaweera 2160 ( PDA! - Holotype) .

Taxonomic Notes: — Oberonia meegaskumburae shows close affinity with O. weragamaensis and distribution of both species seems to be overlapping and both bear reddish-brown flowers, still these two species are very distinct from each other. O. meegaskumburae has much longer inflorescence (~ 10 cm), comparatively larger flowers (3 cm long) against shorter inflorescence (~ 5.6 cm) and smaller flowers (2 mm long) in O. weragamaensis . Floral bracts are longer (1.9 mm) in O. meegaskumburae with lateral lobes of the labellum erect, converging, terete, raised above the column bearing clavate tips facing each other against shorter floral bracts (1 mm) against subtriangular, erect, fleshy, lying parallel to each other with blunt slightly inflated apex. Triangular mid-lobule of the mid-lobe is same in size with that of subtriangular side lobules in O. meegaskumburae whereas the side lobules of mid-lobe more than three times longer than mid-lobule.

Sectional delimitations have been attempted many times for this genus. Lindley (1859) grouped them on the basis of presence (Section: Caulescentes Lindley 1859: 5) and absence of stem (Section: Acaules Lindley 1859: 1). Hooker (1890) grouped them on the basis of very short stem, ensiform radical or subradical leaves (Section Oberonia Hooker 1890: 675 ), stem short or absent, leaves ensiform, sepal unequal, dorsal lanceolate, lateral very much large, orbicular (Section Scylla Hooker 1890: 684 ); leaves radical, terete, fleshy (Section: Myosurus Hooker 1890: 685 ); elongated stem with many equitant short leaves (Section: Acaulescentes Hooker 1890: 685). Schlechter (1911) and Holttum (1953) considered the absence or presence of an articulation at the base of the leaves to be systematically important. Accordingly Schlechter (1911) recognized two subgenera Apotemnophyllum (leaves with joint) and Menophyllum (leaves without joint). Seidenfaden (1968) grouped the species from mainland Asia into nine sections without giving any names, keeping four sections sunder subgenera Apotemnophyllum. However he considered these groupings artificial. Later unsatisfied by his own sections as well as preceding author’s classification, Seidenfaden (1978) did not assign any section to the species of Oberonia while revising the orchids of Thailand. Ansari & Balakrishnan (1990) grouped Oberonia species from India again into six sections without giving any names. Based on the distinct character of the labellum where side lobes are raised vertically above the column, the new species can be placed in the section Scylla of Hooker (1890), section VII of Seidenfaden (1968) and section V of Ansari & Balakrishnan (1990).

Figures

FIGURE 1. Oberonia meegaskumbura Priyadarshana, Wijewardana & Kumar sp. nov., A. Plant with inflorescence–front view. B. Plant with inflorescence–side view. C. Close-up of inflorescence. D. Close-up of flower. E. Fruit.

FIGURE 2. Oberonia meegaskumburae Priyadarshana, Wijewardana & Kumar sp. nov., A. Plant with inflorescence. B. Flower–front view. C. Flower–side view. D–H. Dissected flower; D. Floral bract, E. Dorsal sepal, F1–F2. Petals, G1–G2. Lateral sepals. H. Labellum. I. Pollinium. J. Operculum. K. Fruits. [Drawn by Ishara H. Wijewardhana from live specimens and Wijewardana 012SIT].

FIGURE 3. A view of Adam’s Peak (Samanala) Nature Reserve, Ratnapura district, Sabaragamuwa province, Sri Lanka, habitat of Oberonia meegaskumburae Priyadarshana & Wijewardana & Kumar sp. nov.