Aphyllorchis yachangensis (Orchidaceae), a new holomycotrophic orchid from China Author Qin, Ying https://orcid.org/0000-0003-2683-206X Guangxi Institute of Botany, Guangxi Zhuang Autonomous Region and Chinese Academy of Sciences, Guilin, Guangxi, 541006, China Author Chen, Hailing Guangxi Institute of Botany, Guangxi Zhuang Autonomous Region and Chinese Academy of Sciences, Guilin, Guangxi, 541006, China Author Deng, Zhenhai Management Center of Yachang Orchid National Nature Reserve, Baise, Guangxi, 533200, China Author Liu, Yan Guangxi Institute of Botany, Guangxi Zhuang Autonomous Region and Chinese Academy of Sciences, Guilin, Guangxi, 541006, China gxibly@163.com text PhytoKeys 2021 2021-07-05 179 91 97 http://dx.doi.org/10.3897/phytokeys.179.63994 journal article http://dx.doi.org/10.3897/phytokeys.179.63994 1314-2003-179-91 441C694B2C9D529395AF32225D065E47 Aphyllorchis yachangensis Ying Qin & Yan Liu sp. nov. Figures 1 , 2 Diagnosis. Aphyllorchis yachangensis is similar to A. caudata but differs from the latter mainly by its hypochile with two wings of 1-1.4 x 0.4-0.6 mm (vs. 2-3 x ca. 4 mm), epichile adaxially smooth (vs. densely papillose), lateral lobes triangular-ovate (vs. semicircular), sepals acute at apex (vs. long cuspidate) and column clavate (vs. approximately cylindrical). Detailed morphological comparisons between A. yachangensis and A. caudata are provided in Table 1 . Table 1. Morphological comparison of Aphyllorchis yachangensis and A. caudata .

Characters	A. yachangensis	A. caudata
Plant size	107-113 cm	100 cm
Inflorescence	42-47 cm	rachis to 50 cm
Bracts	lanceolate, 12-30 x 2.8-6.8 mm	narrowly lanceolate, 40-48 x 5-6 mm
Dorsal sepal	lanceolate, 25-40 x 7.9-10.7 mm, apex acute	linear-lanceolate or lanceolate, 30-35 x ca. 8.0 mm, apex long cuspidate
Lateral sepals	lanceolate, 6.1-8.2 mm wide, apex acute	linear-lanceolate or lanceolate, 6-7 mm wide, apex long cuspidate
Petals	lanceolate, 22-27 x 5.6-7.2 mm	lanceolate, ca. 20 x 6-7 mm
Hypochile	6.6-7.1 mm long, with 2 wings; wings semicircular, 1-1.4 x 0.4-0.6 mm	2-3 mm long, with 2 wings; wings ligulate, 2-3 x ca. 4 mm
Epichile	1.9-2.2 cm long, adaxially smooth ; lateral lobes triangular-ovate	ca. 1.2 cm long, adaxially densely papillose; lateral lobes semicircular
Column	1.4-1.6 cm long, clavate (apex obviously inflated)	1.1-1.4 cm long, approximately cylindrical
Flowering period	late June and July	July and August

Figure 1. Aphyllorchis yachangensis A flowering habit B inflorescence C bract D flower in side view E flower in front view F column in top view G column in ventral view H lip, dorsal sepal, lateral sepals, petals, column and ovary I column in side view J lip in side view K lip in top view L pollinaria M anther cap in top view N rhizome and roots. Photographed by Ying Qin from Ying Qin et al. QY20190719001 (holotype: IBK!). Type . China . Guangxi , Baise city, Leye county , Yachang Orchid National Nature Reserve , 1862 m , 19 July 2019 , Ying Qin et al. QY20190719001 ( holotype : IBK! isotype: IBK!) . Description. Herb holomycotrophic, leafless, 107-113 cm tall. Rhizome ca. 10.8 cm long, 4.9-6.2 mm in diameter, densely noded; internodes 2.4-12 mm long. Roots spreading, stout, 3.4-6.4 mm in diameter. Stem 61-71 cm tall, 4.5-7.3 mm in diameter, yellow-green, usually with many dark purple stripes and spots, with 1.4-4 cm long sheaths; the uppermost sheath lanceolate; other sheaths tubular. Inflorescence terminal, racemose, 42-47 cm long, with 19-23 well-spaced flowers; rachis sparsely glandular puberulent, yellow-green, usually with many dark purple stripes and spots. Bracts lanceolate, shorter than pedicel and ovary, 1.2-3 cm long, 2.8-6.8 mm wide, yellow-green, usually with many dark purple stripes and spots on abaxial surface, sparsely glandular puberulent. Ovary cylindrical, yellow-green, usually with many dark purple stripes and spots, sparsely glandular puberulent, 2.2-2.8 mm in diameter, including pedicel to 2.3-3.5 cm long. Sepals yellow-green, usually with many dark purple stripes and spots on abaxial surface, abaxially sparsely glandular puberulent; dorsal sepal lanceolate, slightly concave, 2.5-4 cm long, 7.9-10.7 mm wide, apex acute, reflexed; lateral sepals lanceolate, slightly oblique at base, 2.5-4 cm long, 6.1-8.2 mm wide, apex acute, reflexed. Petals lanceolate, reflexed, 2.2-2.7 cm long, 5.6-7.2 mm wide, yellow-green, pale purple to dark purple at base, apex acute. Lip 2-partite; hypochile narrow, concave, 6.6-7.1 mm long, 3.6-4.5 mm wide, yellow or reddish brown, with 2 unobvious wings at base; wings semicircular, 1-1.4 mm wide at base, 0.4-0.6 mm tall; epichile ca. 1.9-2.2 cm long, 1.3-1.5 cm wide when flattened, 3-lobed, yellow with pale purple, or purple to dark purple, adaxially smooth, margin slightly erose; lateral lobes triangular-ovate, 8.2-8.9 mm long, 3.6-4.3 mm wide; mid-lobe narrowly triangular, 1.1-1.3 cm long, 5.6-5.9 mm wide, acute at apex, margin slightly involute. Column clavate, arcuate, 1.4-1.6 cm long, 1.8-3.3 mm in diameter in lower part, 4.3-6.1 mm in diameter in upper part, yellow-green, usually purple from middle to base; stigma ovate, slightly concave; staminodes 2, on both sides of apex, yellow-white to pale yellow-green; pollinia 2, ovate, granular-farinaceous, 4 mm long, yellow; anther cap ovate, slightly laterally compressed, 4 mm long, pale yellow. Figure 2. Aphyllorchis yachangensis (an individual with dark colors in the same environment with Ying Qin et al. QY20190719001 ) A flowering habit B bud C flower in back view D flower in front view. Photographed by Ying Qin from Ying Qin et al. QYYC20200703009 (paratype: IBK!). Distribution, habitat and ecology. Aphyllorchis yachangensis was discovered in the Yachang Orchid National Nature Reserve, Leye county, Baise city, Guangxi Province, China. The holotype subpopulation is distributed in a subtropical evergreen and deciduous broad-leaved mixed forest, and is found growing with Chimonobambusa quadrangularis (Franceschi) Makino ( Gramineae ), Lithocarpus glaber (Thunberg) Nakai ( Fagaceae ), Manglietia fordiana Oliver ( Magnoliaceae ), Juglans mandshurica Maximowicz ( Juglandaceae ), Dysosma majorensis (Gagnep.) Ying ( Berberidaceae ), Ophiopogon bockianus Diels ( Liliaceae ), Disporopsis fuscopicta Hance ( Liliaceae ), Calanthe brevicornu Lindley ( Orchidaceae ), Goodyera biflora (Lindley) J. D. Hooker ( Orchidaceae ), G. velutina Maximowicz ex Regel ( Orchidaceae ), etc. Phenology. Flowering in late June and July, capsules not seen. Etymology. The specific epithet is derived from the type locality, Yachang Orchid National Nature Reserve. Chinese name. 雅长无叶兰 (Ya Chang Wu Ye Lan) Additional specimens examined ( paratypes ). China : Guangxi : Baise city, Leye county , Yachang Orchid National Nature Reserve , 1862 m , 28 July 2018 , Ying Qin et al. YC3639 (IBK!) ; Guangxi : Baise city, Leye county , Yachang Orchid National Nature Reserve , 1859 m , 03 July 2020 , Ying Qin et al. QYYC20200703009 (IBK!) .