Oberonia langbianensis Gagnep.

Geiger, D. L., 2019, Studies on Oberonia 5 (Orchidaceae: Malaxideae). Twenty-four new synonyms, and a corrected spelling, Blumea 64 (2), pp. 123-139 : 130

Oberonia langbianensis Gagnep. — Fig. 7

Oberonia langbianensis Gagnep. (1932) 168. — Type. Evrard 1402 (lecto Seidenfaden (1968: 16: inadvertent designation) P00292892), [ Vietnam,] Annam, Langbian, ‘planches’ near Dran.

Oberonia dalatensis Gagnep. (1932) 168. — Type. Evrard 1160 (lecto Seidenfaden (1968: 17: inadvertent designation) P00292890), [ Vietnam,] Annam, Dalat, gully behind police station.

Oberonia sulcata J.Joseph & Sud.Chowdhury (1966) 53, f. 1–4. — Type: Joseph 40358 (holo CAL;iso ASSAM),[ India, Arunachal Pradesh,Kameng,] Selari forest, NEFA [The North-East Frontier Agency], 2230 m, syn. nov.

Notes — Oberonia langbianensis , with synonyms O. dalatensis (see Ormerod 2007) and O. sulcata , is one of the four species in sect. Myosurus , a section diagnosed by terete leaves. The other three species are highly distinct. Oberonia cavaleriei has long finger-like projections from the lip, while O. teres Kerr (1927) has linear-lanceolate petals with entire margins, and O. calcarea P.O’Byrne (2017) has a four-lobed lip with warts on the front. The other names have oval-oblong petals with erose margins, a lip with erose margin, and reflexed oval sepals. The distinctness of the apical notch on the lip varies. Particularly illuminating are the illustrations of two flowers from the type of O. langbianensis by Seidenfaden (1968; Fig. 7c ): the flower in frontal view shows no distinct notch, while the flower in ventral view has a distinct notch, intermediate between the condition of the type of O. dalatensis and O. sulcata . The illustrations from the type of O. dalatensis by Seidenfaden (1968; Fig. 7a ) and Averyanov (2013; Fig. 7b ) show differences both in the apical notch as well as the insertion below the lateral lobes. As the flowers are from the same respective plants, it is a clear indication of the variability of the species.

Oberonia sulcata is here synonymised with O. langbianensis as had already been suggested by Seidenfaden (1978) and Ansari & Balakrishnan (1990). Specimens identified with both names have the rather uncommon terete leaves of sect. Myosurus . The shared characters are the T-shaped lip with irregularly erose lateral lobes and indistinctly bilobed epichile with irregularly erose margins, the petals with erose margins that are broader than the median sepal, the acuminate floral bract with erose margin, the reflexed sepals, and the inflorescence with distinctly pedunculate flowers in loose whorls. The sizes of the whole flower and the isolated lip are incongruent ( Fig. 7e ). All illustrations of Fig. 7 were scaled to one common scale bar based on the scale bars in the respective publications.

Figures

Fig. 7 Illustrations of the types of: a–b. O. dalatensis; c. O. langbianensis; d–e. O. sulcata. — a, c. From Seidenfaden (1968); b. lip and petal from Averyanov (2013); d. flowers, sepal with entire margin, petal with erose margin, and lip from Joseph & Cowdhury (1966); e. flower, isolated lip, and bract, from Ansari & Balakrishnan (1990). — Scale bar for all illustrations = 1 mm. Arrows highlight the variable condition of the apical notch of the epichile.