Oberonia bicornis Lindl.

Geiger, D. L., 2019, Studies on Oberonia 5 (Orchidaceae: Malaxideae). Twenty-four new synonyms, and a corrected spelling, Blumea 64 (2), pp. 123-139 : 124

Oberonia bicornis Lindl. — Fig. 1

Oberonia bicornis Lindl. (1830) 16. — Type: Wallich 1949 (syn E 00394097, K 001114799), [Eastern India, today Bangladesh,] Sillet [= Sylhet].

Oberonia tenuis Lindl.(1859) 3. — Type: Thwaites 2654 (syn K 000974229), Ceylon [= Sri Lanka], Hittàwaka, on trees, syn. nov.

Notes — Oberonia tenuis is here synonymised under O. bicornis , a synonymy already suspected by Ansari & Balakrishnan (1990). Santapau & Kapadia (1966) distinguished O. bicornis by the shape of the petals, the lateral lobes of lip linear-lanceolate, erect, not filiform and incurved, mid-lobe of lip fleshy cuneate truncate, not broadly three-lobed with long ends. However, Lindley (1859: 4) described O. bicornis as having a crescent, i.e., curved lateral lobes of the lip, disabling Santapau & Kapadia’s (1966) argument. The examined Lindley specimens (K) as well as drawings of the Lindley specimens of both names available in the W Reichenbach collection and from Seidenfaden (1968) show identical flowers ( Fig. 1 ), including some variability in the orientation of the auricles.

Other names in the section Scylla need to be carefully evaluated. All have very limited material associated with them and there is little information on intraspecific variability. The size indications of the flowers need to be viewed with much caution because of demonstrable inaccuracies and errors with scale bars in the literature (see below). Some characters used to describe those species are known to be highly variable, including size of the plant, length of the inflorescence, and colour of the peduncle-rachis. The last can be demonstrated from species in cultivation, because peduncle-rachis colour varies on the same plant among different flowering periods. The same plant of O. rufilabris can either have bright green to dull orange peduncles and rachis (DLG395: HOAG85 green, HOAG193 yellow-green, HOAG138 yellowish. DLG515: HOAG95 bright green, HOAG156, HOAG197 yellowish green, HOAG151 orange. DLG476: HOAG136 bright green, HOAG133, HOAG179, HOAG201 yellowish green). A character that is variable on the same plant is unsuitable in taxonomy. This example highlights the complementary nature of herbarium records from cultivated plants (Geiger 2018) in the context of taxonomic assessments. Two examples illustrate the above. Oberonia dolabrata Jayaw. is only distinguished by the hairs along the margin of the petals. Specimens of O. tenuis (without hairy petals) have been reported from India and Sri Lanka ( Ansari & Balakrishnan 1990). It is an omission that Jayaweera (1981) only compared O. dolabrata to O. bicornis with type locality in Bangladesh, but not to O. tenuis with a Sri Lankan type locality.

As a second example, O. meegaskumburae Priyad., Wijew. & Kumar in Priyadarshana et al. (2017: t. 1) was distinguished from O. weragamaensis Jayaw. (1963) by the size of the plant and the inflorescence (variable), and the colour of the peduncle (variable), and on the size of the flower. Based on the demonstrable intraspecific variability of flower size in general (see O. complanata ), I consider such indications as unreliable and of questionable taxonomic value. The cited difference in size of the pedicelled ovary (0.8 × 0.3 mm vs 3.5 × 1.6 mm) is clearly a comparison of an unfertilised pedicelled ovary with a developed seed capsule ( Priyadarshana et al. 2017: f. 1E, 2K). Morpho- logical comparisons always have to be made on organs in the same stage of development. While the alleged differentiating characters are demonstrably unreliable in other species, the limited material for O. meegaskumburae and O. weragamaensis precludes a firm conclusion in this instance at this time.

Figures

Fig. 1 a–b. Oberonia bicornis Lindl. drawing of Type: a. Reichenbach her- barium 9857; b. Oberonia tenuis drawing of type in Reichenbach herbarium 35460. Figure rotated 180˚ to show flowers in same orientation.