Calanthe insularis S.H.Oh, H.J.Suh

Oh, Sang-Hun, Suh, Hwa-Jung, Park, Chong-Wook, C. - W & C. - W, 2015, Two new species of Calanthe (Orchidaceae: Epidendroideae) from Korea, Phytotaxa 218 (1), pp. 69-76 : 69-72

1. Calanthe insularis S.H.Oh, H.J.Suh & C.-W.Park, sp. nov. ( Figs. 1 , 2 )

Type:— KOREA. Jeollanam-do: Sinan-gun, Heuksan-myeon, Gageodo Island , 386 m, 18 May 2013, Suh 5580 (holotype, KB!; isotypes, BH!, TUT!) .

Diagnosis: This species is similar to C. striata and C. aristulifera , but differs by its creamy yellow and pale orange-yellow flowers, arcuate spur as long as the lip, pale orange-yellow pedicels, and green ovary with pale green ridges.

Plants herbaceous, terrestrial, 33–43 cm tall. Pseudobulbs ovate or conical, 1–2 cm long, 1–2 cm in diameter. Leaves 3 or 4, biennial, incompletely spreading and convolute at anthesis, base forming a pseudostem, fully developed blade elliptic or obovate-elliptic, 34–48 cm long, 9–13 cm wide, contracted basally into a petiole-like stalk, 9–13 cm long; blade entire, puberulent abaxially, glabrous adaxially, apex acuminate. Inflorescences racemose, erect on a scape arising from leaf axil, 33–43 cm long, puberulent; rachis 22–30 cm long, loosely 7–15-flowered; floral bracts lanceolate, 6–7 mm long, yellow, persistent. Flowers pale orange-yellow outside, creamy yellow inside; pedicel and ovary 1.8–2.1 cm long, densely puberulent, pedicel pale orange-yellow, ovary green with pale green ridges. Sepals subequal, ovate to oblong-ovate, 2.2–2.6 cm long, 0.9–1.0 cm wide, apex acuminate, sparsely purberulent, 5–7-veined; dorsal sepal concave, cymbiform; lateral sepals slightly narrower than dorsal sepal. Petals narrowly elliptic, 1.9–2.4 cm long, 0.6–0.8 cm wide, base narrowed, apex acuminate; lip adnate to column wings, flabellate, creamy yellow, mottled red at base, deeply trilobed; midlobe obovate, wing-like, spreading, 5.6–9.2 mm long, apex slightly lobed, mucronate in sinus; lateral lobes falcate-obovate, oblique, 5.4–7.6 mm long, apex rounded; disk with 3–5 ridges and 2 rows of white short hairs at base; spur slightly arcuate, parallel to ovary and pedicel, 1.0– 1.3 cm long, pale yellow to creamy yellow, obtuse apically, puberulent. Column ca. 5 mm long, thick; rostellum bilobed; pollinia waxy, in 2 groups of 8, with short caudicles, attached to an elliptic viscidium. Fruit ovoid, nodding. Fl. May.

Additional specimens examined:— JAPAN. Nagasaki-ken, Tsushima-shi, Izuharamachi , Mt. Taterayama , 4 May 2014, Suh 5907 ( TUT!) . KOREA. Jeollanam-do: Sinan-gun, Heuksan-myeon, Gageodo Island , 386 m, 17 May 2014, Oh & Suh 5930, 5932, 5935 ( TUT!) ; Hongdo Island , 25 May 2014, Suh 5987, 5989 ( TUT!) .

Distribution and habitat:— Calanthe insularis occurs under broadleaf evergreen forests dominated by Castanopsis cuspidata (Thunberg) Schottky on Gageodo Island, Hongdo Island, and Tsushima Island. Gageodo Island and Hongdo Island are small offshore islands near the southwestern coast of Korea, and Tsushima Island is a large island situated in the Korea Strait between the Japanese mainland and the Korean Peninsula. The population size of C. insularis is small with less than 30 individuals per location and is decreasing because of habitat destruction and collection for horticulture.

Phenology:— Calanthe insularis flowers in May, and fruiting occurs June to August. Mature fruits of C. insularis may last until March of the next year.

Etymology:— The specific epithet of C. insularis refers to its distribution on islands.

Discussion:— Calanthe insularis is morphologically similar to C. aristulifera and C. striata , which are often found close to the new species. In particular, patches of C. striata were found within one kilometer from individuals of C. insularis in all localities examined. Plants of C. aristulifera are also distributed near patches of C. insularis on Gageodo and Hongdo islands. Plants of C. insularis have been identified as C. × kibanakirishima Maekawa (1971: 363) because they occur near C. striata and C. aristulifera ( Hong et al. 2010) . Calanthe × kibanakirishima was originally reported as a natural hybrid between C. aristulifera and C. striata ( Maekawa 1971) , but the name was not validly published, lacking a Latin description and diagnosis (ICN Melbourne code Art. 39.1, McNeill et al. 2012). According to Maekawa (1971), C. × kibanakirishima shows the combination of the pseudobulbs, leaves, and lip of C. aristulifera and the sepals and petals of C. striata . The illustration ( Maekawa 1971) shows that the lip is pale purple in color, similar to C. aristulifera , and the sepals and petals are yellow to greenish yellow in color resembling those of C. striata . The flowers of C. insularis differ from the illustration ( Maekawa 1971) in having a creamy yellow lip that is the same color as the other perianth parts ( Fig. 2 ). Preliminary analyses of plastid and nuclear DNA sequences suggested that C. insularis is closely related to C. aristulifera and is not of hybrid origin ( Oh et al. 2014).

Calanthe insularis is distinguished from C. aristulifera and C. striata in its creamy yellow and pale orange-yellow flowers, arcuate spur as long as the lip, pale orange-yellow pedicels and a green ovary with pale green ridges ( Table 1, Fig. 3 ). In addition, the flowers of C. insularis are larger than those of C. aristulifera but smaller than those of C. striata . Specifically, the size of the dorsal sepal and petals of C. insularis is larger than that of C. aristulifera and slightly smaller than that of C. striata ( Table 1). Clear differences among the three species are found in the lip and spur. The spurs of C. insularis and C. striata are slightly arcuate parallel to the ovary, and the spur of C. aristulifera is curved upward ( Fig. 3 ). Calanthe insularis differs from C. striata with respect to the length of the lip and spur. Compared with C. striata , C. insularis has a shorter lip but a longer spur ( Table 1, Fig. 3 ). As indicated by the ratio of the spur-to-lip length ( Table 1), the spur and the lip are similar in size in C. insularis , whereas the spur is much shorter than the lip in C. striata . The color of the pedicel of C. insularis is pale orange-yellow, which is the same as the abaxial surfaces of the sepals and petals, and the ovary is green with pale green ridges. Both the ovary and pedicel of C. striata are green ( Table 1, Fig. 3 ). Calanthe insularis is considered endangered ( IUCN 2014; EN B2a,b(iii)) because of its limited occurrence on islands in southwestern Korea and Tsushima Island

Figures

FIGURE 1. Calanthe insularis (Nagasaki-ken, Japan). Part of a mature leaf is broken. A. Plant. B. Flower, front view. C. Flower, lateral view. D. Lip. E. Sepals and petals. F. Pollinia. Scale bar: A = 4 cm; B, C = 1 cm; D = 5 mm; E, F = 1 mm.

FIGURE 2. Photograph of Calanthe insularis from Sinan-gun, Korea.

FIGURE 3. Comparison of Calanthe insularis (A and E) and C. rubra (B and F) with C. striata (C and G), and C. aristulifera (D and H). A–D. Front view of flower. E–H. Lateral view of flower. Scale bar = 1 cm.