Oberonia aporophylla Rchb.f.

Geiger, D. L., 2020, Studies in Oberonia 8 (Orchidaceae: Malaxideae). Additional 24 new synonyms, a corrected spelling, and other nomenclatural matters, Blumea 65 (3), pp. 188-203 : 189-190

Oberonia aporophylla Rchb.f. — Fig. 1

Oberonia aporophylla Rchb.f. (1855) 223. — Syntypes: Cuming 2113 ( BM000088320 , K s.n., K s.n. Drawing from type at Vienna Reichenbach Herbarium #37820 W68779. Additional pocket labelled Cuming 2112 or Cuming 2113 with flower parts and leaf sample. Agrees with drawing of Cuming 2113 on herbarium sheet. Philippines in protologue; Bohol on K syntype.

Oberonia longirepens J.J.Wood in J.J. Wood et al. (2011) 434, f. 2.214. — Type: Clemens 50250 (holo SING: not found in 8/2018, iso K 73164 : not found 4/2018), [ Malaysia, Sabah,] Tenompok Orchid Garden , 1500 m, syn. nov.

Notes — Oberonia aporophylla and O. longirepens are conspecific. The overall habit of erect stems with short imbri- cate leaves and creeping rhizomes ( Fig. 1a, c ) in conjunction with multiple floral attributes, such as the narrow petals, the presence of distinct auricles on the lip, the bilobed epichile of the lip with serrated edges ( Fig. 1b, d ) clearly show that the two names refer to the same species. One of the most striking characters is the creeping rhizome, typically associated with the genus Hippeophyllum Schltr. While Reichenbach (1855) did not mention this character in the protologue, it is found on historical herbarium records such as Vanoverbergh 1919, P00263280 from Luzon, the Philippines, collected in flower in October 1912, is known from field observation in the Philippines (Ronny Boos, pers. comm.), and from horticultural specimens of Philippine provenance seen by the author ( Fig. 1e–k ). The probability of two species with identical vegetative growth and flowers, but with and without rhizomes, is extremely unlikely.

Wood et al. (2011) did not compare O. longirepens to any species occurring outside of Borneo, and only noted the distinct creeping habit and the salmon coloured flowers. The colour of the flower can vary extensively in Oberonia species. Oberonia aporophylla is known in light cream and yellow-green forms ( Fig. 1e–f ), with salmon rachis ( Fig. 1f ). The salmon colour of the flower is well within the expected range.

The illustration for the flower of O. longirepens might erroneously suggest different proportions of the floral elements. However, the measurements of the floral elements in Wood et al. (2011) are incongruent with the drawings, both in relative and absolute terms. The sepals as well as the petals are indicated as being 0.9 mm long, but petals are markedly smaller in the drawing compared to the sepals. Based on the 1 mm scale bar, the sepals are at least 1.0 mm long, while the petal is only 0.7 mm long. The lip is described as 0.9–1 mm long, while from top of auricles to longest projection of epichile it is 0.85 mm based on the 0.5 mm scale bar provided. From that follows, that the proportion of the sepals to lip is off by 15 % in the drawing. The implied live position of the lateral sepals is equally misleading ( Fig. 1d ). While the drawing shows them inclined towards the petal and median sepal, they are actually pointed away at an approximately 120° angle, as shown in the much more realistic drawing on the syntype sheet of O. aporophylla at K ( Fig. 1b ). Notice also the absence of disc and a fortiori the sac in both drawings. It is a further example that drawings are frequently highly inaccurate, even by well-respected authors in highly regarded publications.

Unfortunately, the type specimens of O. longirepens allegedly deposited at SING and K were not found during collection visits in 2018. The K on-line data portal does not have an image of the specimen, suggesting it was never deposited there. The fate of those type specimens is unknown. The collector is given as ‘Clemens’ in the protologue, while the K data portal gives J. Clemens & M.S. Clemens . As the type sheets are missing, the collector could not be verified.

A biogeographic distribution spanning from the Philippines to Borneo is well within the dispersal abilities of plants with minute seeds. The seeds of O. aporophylla are approximately 150 µm long ( Fig. 1l ), typical for Oberonia spp. ( Barthlott et al. 2014, Geiger 2014, unpubl. data, Geiger et al. 2020).

Figures

Fig. 1 Oberonia aporophylla. a–b. Syntype in K. a. Habit; b. flower; c–d. drawing of O. longirepens (a synonym of O. aporophylla) from Wood et al (2011): c. habit; d. sepals and petals, digitally re-arranged and scaled according to scale bars on drawings; the relative and absolute size of the floral elements are highly inaccurate, see text for details; e–f. z-stack colour photographs of O. aporophylla. e. Light cream form; f. yellow form with salmon rachis; g–i. SEM images of flowers; j–k. enlargement of central portion of lip showing disc; j. central portion of lip; k. details of cell surface sculptures with rugulate cells on mesochile and cross striate cells in central channel; l. seeds, from plant of Andy’s Orchids nursery (e, g–h, j–k: DLG 394, HOAG 49; f: DLG 599, HOAG 248; i: DLG 599, HOAG 50). — Scale bars: f–i = 1 mm; j–l = 100 µm.