Gastrodia nipponicoides Suetsugu, 2017

Suetsugu, Kenji, 2017, Two new species of Gastrodia (Gastrodieae, Epidendroideae, Orchidaceae) from Okinawa Island, Ryukyu Islands, Japan, Phytotaxa 302 (3), pp. 251-258 : 252-254

Gastrodia nipponicoides Suetsugu , sp. nov. ( Figs. 1–2 )

Type: — JAPAN. Ryukyu: Okinawa Pref., Okinawa Island, Kunigami Village, Mt. Yonaha, 29 March 2016, Moriguchi s.n. (holotype: KYO!).

Gastrodia nipponicoides is similar to G. nipponica (Honda) Tuyama (1939: 4) , but it is distinguished by its shorter perianth tube, lack of rostellum and fewer ridges on the lip.

Terrestrial, mycoheterotrophic herbs. Roots few, slender, often produced from the junction between rhizome and inflorescence after the flowering season. Rhizome tuberous, fusiform or cylindrical, 20–50 mm long, 3–9 mm in diameter, yellowish brown, covered with numerous scales and root-hair-like unicellular hairs. Inflorescence erect, dark brown, 3–6 cm long, ca. 3 mm in diameter, 3–4 nodes, with tubular, membranous sheaths. Bracts ovate, up to 5 × 3 mm. Pedicel and ovary up to 6 mm long. Flowers 1–4, tubular, slightly tilted upwards or downwards, resupinate, 15–17 mm long, 8–9 mm in diameter. Sepals and petals united, forming a five-lobed perianth tube. Sepals subsimilar, 15–17 mm long, adnate ca. 3/4 their length with petals, lateral ones connate ca. 3/4 their length, outer surface dark brown with numerous white warty spots, margin entire; free portion of dorsal sepal straight, ovate-triangular, obtuse at apex, ca. 4 mm long, 4 mm wide; free portions of lateral sepals, triangular, acute at apex, ca. 4 mm long, 4 mm wide. Free portions of petals ovate or elliptic, 2.5–3.0 × 2.0– 2.5 mm. Lip joined with perianth tube, ca. 10 mm long, hypochile pale green without any appendages or calli; epichile pale dark green to whitish reddish orange, rhombic-ellipse, base contracted, disc 2 reddish orange ridged extending toward apex, margin slightly undulate, the apical portion ligulate, reddish orange, ca. 1.5 mm wide. Column straight, semi-cylindrical, 7.0–8.0 × 2.0– 2.5 mm, white; lateral wings (stelidia) distinct, the edges parallel to column, base slightly angled, apex acute; rostellum absent. Anther hemispheric, 1.0– 1.5 mm in diameter, pollinia 2. Capsule cylindrical, ca. 3 cm long, pedicel elongating to ca. 20–30 cm long in fruit. Seeds fusiform, ca. 2 mm long.

Additional specimens examined: — JAPAN. Ryukyu: Okinawa Pref., Okinawa Island, Kunigami Village, Hungawa, 20 March 2016, Toma, Watanabe, Watanabe s. n. ( KYO).

Distribution and phenology:— To date, the distribution of G. nipponicoides is restricted to Okinawa Island. Flowering was observed from mid-March to late-March, and fruiting throughout April.

Taxonomic notes:— Gastrodia nipponicoides is morphologically similar to G. nipponica in its elongated perianth tube and small stature. However, G. nipponicoides can be distinguished by the shorter perianth tube (15–17 mm vs. 18–24 mm), colour of the perianth tube (dark brown with numerous white, warty spots vs. dark brown), lip morphology (epichile with 2 ridges vs. epichile with 4–6 ridges), the rostellum condition (degenerate vs. ca. 0.7 mm long) and the stigma positon (slightly above middle vs. basal).

Figures

FIGURE 1. Gastrodia nipponicoides from the type locality. A. Flowering plant. B. Flower, side view. C. Flower, from front view.

FIGURE 2. Gastrodia nipponicoides (from the holotype). A. Habit. B. Dissected flower. C. Flower, longitudinal section. D. Flattened perianth tube. E. Flower, view from above. F. Flower, side view. G. Flower, bottom view. H. Lip. I. Anther cap, from below. J. Anther cap, from above. K. Column, bottom view. L. Column, side view. M. Column, top view. A. Bar = 1 cm.. B–H. Bar = 5 mm. I–M. Bar = 1 mm.