Flora of China 25: 57–63. 2009. 10. CHEIROSTYLIS Blume, Bijdr. 413. 1825. 叉柱兰属 cha zhu lan shu Chen Xinqi (陈心启 Chen Sing-chi); Stephan W. Gale, Phillip J. Cribb, Paul Ormerod Arisanorchis Hayata; Gymnochilus Blume; Mariarisqueta Guinea. Herbs, terrestrial or occasionally epiphytic, small. Rhizome decumbent, moniliform to terete, fleshy, with many contracted nodes; roots usually reduced to fine hairs and arranged along ridges on rhizome internodes, rarely fleshy and emerging from rhizome nodes. Stem erect, very short to elongate, glabrous, with 2 to several subrosulate or scattered cauline leaves. Leaves often withered at anthesis, ovate to cordate, with a short petiole-like base dilating into a tubular amplexicaul sheath. Inflorescence erect, terminal, racemose, very short to elongate, 1- to many flowered, glabrous to pubescent. Flowers resupinate, usually small, mostly not secund; ovary shortly pedicellate, twisted, fusiform, glabrous to pubescent. Sepals membranous, outer surface glabrous to pubescent, connate for half to almost entire length and forming a tube, or rarely free. Petals usually connivent with dorsal sepal; lip adnate to column margin at base, sometimes simple and entire though usually 3-partite; hypochile often dilated and saccate, containing fleshy, lobed or seriate (comblike) papillose calli; mesochile subtubular, short to elongate; epichile spreading, 2-lobed or rarely entire, margin laciniate, dentate, wavy, or entire. Column short, ventrally with 2 elongate armlike appendages (stelidia) parallel to rostellum; anther erect, ovoid, 2-locular; pollinia 2, each longitudinally 2-partite, granular-farinaceous, clavate, attached to solitary oblong viscidium; rostellum deeply bifid, 2 elongate arms erect, parallel; stigma lobes 2, separate, convex, rather large, placed laterally near apex of column and below rostellum. Capsule ellipsoid. About 50 species: from tropical Africa through tropical Asia to New Guinea, Australia, and the Pacific islands; 17 species (eight endemic) in China. Hayata considered species with an entire lip to comprise a distinct genus, Arisanorchis, but they conform to Cheirostylis in other respects (sepals basally fused and forming a tube, column with two elongate stelidia, rostellum deeply bifid) and are most likely peloric forms. A monographic revision of the genus is highly desirable given that overlapping species concepts remain a problem in separating taxa named from different regions. The endemic species of Taiwan and Hong Kong in particular remain poorly known and are in need of re-examination. 1a. Leafy stem elongate, (1.5–)3–8 cm; leaves cauline, scattered, sometimes becoming clustered toward apex of stem; inflorescence shorter than, equal to, or sometimes slightly longer than (but always less than 2 × as long as) leafy stem. 2a. Leaves elliptic-oblong, 5–7 cm; sepals free, not forming a tube ................................................................. 1. C. tabiyahanensis 2b. Leaves usually ovate, 0.4–3.2 cm; sepals connate for 1/2–3/5 of length and forming a tube. 3a. Leaves up to 0.7 cm; sepals 2.5–3 mm ................................................................................................................ 2. C. pusilla 3b. Leaves 1–3.2 cm; sepals 3–11 mm. 4a. Inflorescence to 1 cm, peduncle often enclosed by leaf bases and not visible beyond stem apex; ovary glabrous; petals 9–10 mm; hypochile calli comblike, composed of several seriate papillose appendages. 5a. Apices of sepals acute; epichile without a tooth at apex between 2 lobes, lobes deeply 4- or 5-laciniate, each division 3–4 mm .................................................................................................. 3. C. octodactyla 5b. Apices of sepals obtuse; epichile with an acute tooth at apex between 2 lobes, lobes 5- or 6-laciniate, each division 1–2 mm .............................................................................................. 4. C. pingbianensis 4b. Inflorescence 2–7 cm, peduncle long, free of leaf bases and visible beyond stem apex; ovary pubescent or villous; petals 4–4.5 mm; hypochile calli bifid. 6a. Leaves ovate to lanceolate, 1.5–2.2 cm, petiole-like base and sheath 1.5–1.8 cm; epichile lobes deeply 4- or 5-laciniate .......................................................................................................... 5. C. tortilacinia 6b. Leaves ovate-orbicular, 2–3 cm, petiole-like base and sheath 0.7–0.9 cm; epichile lobes wavy to shallowly 2- or 3-dentate, teeth broad with acute tips ....................................................... 6. C. liukiuensis 1b. Leafy stem usually no more than 3 cm (rarely to 5 cm); leaves subrosulate or congested at base of stem; inflorescence at least 2 × as long as leafy stem. 7a. Lip simple, entire; hypochile lacking papillose calli. 8a. Ovary and outer surface of sepals glabrous; lip spatulate, 3–5 mm ......................................................... 7. C. clibborndyeri 8b. Ovary and outer surface of sepals pubescent; lip narrowly oblong, 6–8 mm ...................................................... 8. C. takeoi 7b. Lip 3-partite; epichile lobes dentate or laciniate at margin, hypochile containing papillose calli. 9a. Sepals and petals 13–15 mm; lip 15–17 mm .................................................................................................... 9. C. griffithii 9b. Sepals and petals 3–6.5(–9) mm; lip 5–12 mm. 10a. Hypochile shortly spurred .................................................................................................................... 17. C. calcarata 10b. Hypochile saccate, never spurred. 11a. Hypochile divided by a longitudinal septum into 2 parts, each part with (1 or)2 horn-shaped calli .................................................................................................................... 13. C. malipoensisFlora of China 25: 57–63. 2009. 11b. Hypochile lacking a longitudinal septum; calli bifid or comblike. 12a. Epichile lobes deeply laciniate, divisions narrowly linear; hypochile calli bifid. 13a. Rhizome moniliform, olive-green; leaves 0.8–1 cm wide, petiole-like base to 4 mm; lip 8–11.5 mm ............................................................................................... 10. C. monteiroi 13b. Rhizome torose, reddish; leaves 1.2–1.7 cm wide, petiole-like base 4–10 mm; lip 5–6 mm