Zeuxine ovalifolia L. Li & S. J. Li, 2013

Li, Lin & Li, Shi-Jin, 2013, A new species of Zeuxine (Cranichidae; Orchidaceae) from Hainan, China, Phytotaxa 129 (1), pp. 65-68 : 65-67

Zeuxine ovalifolia L. Li & S. J. Li , sp. nov. ( Fig. 1 )

Species similar to Z. agyokuanae Fukuy but with much smaller ovate leaves, broader and more sparsely ciliate floral bracts, narrower and united dorsal sepal and petals, and a yellow to orange-yellow hypochile of the lip with bi- or trilobed calli.

Type: — CHINA. Hainan Province: Wuzhishan Mountain National Nature Reserve , in tropical rainforest, 18° 53’ N – 109° 41’ E, 1,380–1,400 m, 1 September 2012, Li 0466 (holotype: IBSC!) .

A terrestrial herb with creeping rhizome and ascending leafy stem. Rhizome terrete, 5–6 cm long, rooting at nodes; internodes 1.2–2.0 cm. Roots arising from rhizome nodes, pubescent. Stem 4–5 cm tall, glabrous, enveloped by tubular, leaf-bearing sheaths. Leaves 6–7, cauline, alternate, sheathing petiolate; petiole and sheath 0.5–1.0 cm long; leaf blade ovate, margin entire, base rounded, apex acute, 1.6–2.2 × 0.7–1.0 cm, deep green to green, grayish-green beneath without white markings. Inflorescence terminal, erect, racemose, sparsely pubescent; peduncle ca. 9.5 cm long, with 2 sterile bracts, 4.0–7.0 × 0.5–1.0 mm, pinkish brown; rachis 3.0– 3.5 cm long, loosely spaced with 4–6-flowers. Floral bracts shorter than the ovary, tubular, redbrown, apex acuminate, margin sparsely ciliate or fringed, 6.0–6.5 × 1.5–2.0 mm. Pedicel and ovary fusiform, subglabrous, twisted, 7.5–8.0 × 0.8–1.5 mm, dark brown. Flowers about 6.0– 6.5 mm across, red-brown with a yellow and white lip. Sepals subglabrous, subsimilar; dorsal sepal 5.2–5.4 × 1.4–1.7 mm, oblong-lanceolate, concave below middle or near base, apex obtuse, red-brown; lateral sepals spreading, narrowly oblonglanceolate, 4.0–4.2 × 1.0– 1.4 mm, acuminate, margin slightly involute, apex obtuse, adaxially olive-green tinged red-brown, abaxially red-brown. Petals glabrous, oblique, slightly falcate, 4.8–5.0 mm long, broad in the middle, narrowing suddenly towards the apex, closely joined or united to the dorsal sepal forming a forward hood over column, white. Lip cymbiform, fleshy, saccate at base, 4.0– 4.3 mm long, 1.2–1.5 mm thick at base, with a short mesochile and tripartite, orange-yellow to bright yellow at base, white at apex (epichile); hypochile concave-saccate, ca. 3 mm long, inside bearing a pair of irregularly toothed warts on each side, honey yellow, bipartite or tripartite, somewhat dentate, apex obtuse; mesochile involute, folded inward, dentate to jagged along margin; epichile attenuate, narrower than hypochile, broad ligulate, 1.0– 1.2 mm, margins slightly inflexed, apex obtuse, strongly recurved. Column ca. 2.5 mm long, dilated toward apex, without appendages; rostellum 1.5–1.8 mm long, deeply cleft or bifid, thickened toward the apex and clavate; stigma 2, lateral. Anther ovoid-lanceolate, bilocular, 2.3–2.5 mm long, apex acuminate. Pollinia 2, narrowly clavate, granulose, bipartite and basally attenuate into caudicles, attached to a single oblong viscidium.

Distribution and habitat:— The species has a restricted distribution and is so far known only from the type locality. It occurs in shaded rainforests on moist soil covered with leaf litter.

Phenology:— Flowering from late August to early September.

Etymology:— The name of the species was chosen due to its ovate leaves.

Taxonomic remarks:— Zeuxine ovalifolia overall is similar to Z. agyokuana Fukuyama (1934: 433) from the Ryukyus Islands and northern Taiwan, but Z. ovalifolia can be easily distinguished mainly in having much smaller ovate leaves (1.5–2.2 cm), alternate, not clustered apically, margin not undulate; broadly ovate bracts, margin sparsely ciliate towards the apex; falcate petals and conspicuously narrower, oblong-lanceolate dorsal sepal (index c. 5.5/1.7) entirely fused together, as compared to obovate petals and ovate dorsal sepal (index c. 4.0/2.8) connivent or adherent, overlapping each other, lip hypochile with warty, bi-trilobed calli, broad, not uncinate or hooked. Furthermore, Z. ovalifolia is yellow to orange-yellow in the largest part of the lip, whereas in Z. agyokuana it varies from white to pinkish white.

Figures

FIGURE 1. Zeuxine ovalifolia. A. Habit. B. Front view of flower. C. Lateral view of flower. D. Dorsal view of petals and dorsal sepal united in a hood. E–F. Lateral sepals. G. Lateral view of column and lip. H. Ventral view of column and rostellum. I. Lip. J. Pollinaria. K. Anther. Drawn from the holotype by Yun-Xiao Liu.