The monopodial orchid genus Gastrochilus Don (1825: 32) (Epidendroideae; Vandeae; Aeridinae) is identified by the lip, which is typically biparted with a saccate hypochile and broad epichile that connects the lip tothe column, two porate, globose pollinia borne on slender stipe and a bilobed viscidium, and a short axillary inflorescence. It is represented by 53 species distributed from India to Japan (Govaerts et al.2013). Twenty-nine species have been reported from China, of which 17 are believed to be endemic (Chen et al.2009: 491).
Hong Kong is endowed with a wide diversity of orchid taxa representing all five subfamilies (Barretto et al. 2011), and new records continue to be added (e.g. Gale et al.2013). During a recent routine survey of upland forest in the central New Territories, an unusual lithophytic orchid was discovered. It was tentatively identified as a species of Gastrochilus section Microphyllae Bentham & Hooker (1883: 579), which is characterised by plants with numerous distantly spaced leaves compared to plants in the other section, Gastrochilus, which have clustered leaves. After undertaking a comprehensive literature and herbarium review, as well as consulting experts from the region, the authors realised that the taxon had previously been collected on several occasions from different localities outside Hong Kong (i.e. southern China and Vietnam), but it had remained confused with morphologically similar taxa and therefore not properly identified. Further examination of this species alliance revealed several unresolved taxonomic issues regarding the identity and circumscription of its constituent taxa, and eventually this allowed us to determine that the plants discovered in Hong Kong actually belong to a species new to science. We therefore performed a comprehensive morphological and taxonomic review of six allied species from the region, namely, Gastrochilus corymbosus Das & Chanda (1989: 401), G. distichus (Lindley 1858: 36) Kuntze (1891: 661), G. formosanus (Hayata 1911: 336) Hayata (1915: Additions and Corrections), G. fuscopunctatus (Hayata 1912: 143) Hayata (1917: 78), G. jeitouensis Ormerod (2013: 24) and G. pseudodistichus (King & Pantling 1895: 341) Schlechter (1913: 315). In this article, the Hong Kong plants are formally described as new, and notes on distribution, ecology and conservation are provided. A lectotype is selected for G. pseudodistichus, and G. jeitouensis is newly reduced to synonymy of G. distichus. The name G. fuscopunctatus, formerly treated as a synonym of G. pseudodistichus (Jin et al. 2010: 32), is shown to constitute a distinct species and accordingly is reinstated. Keys for the identification and a table for the differentiation of these closely allied species are presented.
Gastrochilus kadooriei Kumar, S.W.Gale, Kocyan, G.A.Fisch. & Aver. sp. nov. (Figs 1, 2, 3A,B)
Type:-CHINA. Hong Kong: Tai Mo Shan, 27 July 2013, Kumar 12022 (holotype: KFBG!).
Diagnosis: Gastrochilus kadoorieiis similar to G. fuscopunctatus, but can be differentiated on the basis of its glabrous, triangular epichile, as compared to that of the latter, which is elliptic-orbicular and hirsute. In addition, the leaves of the new species are ovate, the length of its stem internodes is more than 5 mm and the length of inflorescence is less than 1 cm, whereas the leaves of the latter are oblong, the length of its stem internodes is less than 5 mm, and the length of its inflorescence is more than 1 cm.
FIGURE 1. Gastrochilus kadooriei
A. Plant habit. B. Plant with inflorescence. C–E. Variation in leaf apices. F–H. Front, partial and side view of flower. I–K. Front, partial and side views of labellum with column and ovary. L. Sepals and petals. M. Labellum. N. Pollinarium. O. Anther cap.
FIGURE 2.Gastrochilus kadooriei
A. Plant in habit. B. Plant with inflorescence. C. Close-up of flower (front view). D. Side view of flower. E–F. Petals and sepals, showing colour pattern and venation. G. Labellum with column and ovary. H–J. Variation in leaf apices. K. Anther cap. L. Pollinarium.
[Drawn by P. Kumar from live specimens and Kumar 12022]
FIGURE 3. A. Gastrochilus kadooriei. B. Fruit of Gastrochilus kadooriei. C. Gastrochilus pseudodistichus. D. Gastrochilus distichus. E. Gastrochilus formosanus. F. Gastrochilus fuscopunctatus.
[Photographs by: A-Pankaj Kumar, Hong Kong; B-L. Averyanov, Vietnam; C-Marni Tarkel; D-Xiao-Hua Jin, China; E-Jody Hsieh, Taiwan; F-Su Dung Sheng, Taiwan].
Pankaj Kumar, Stephan W. Gale, Gunter A. Fischer, Ji-hong Li
Kadoorie Farm and Botanic Garden, Lam Kam Road, Tai Po, New Territories, Hong Kong; E-mail: firstname.lastname@example.org
University of Potsdam, Institute of Biochemistry and Biology, Biodiversity Research/Systematic Botany, 14469 Potsdam, Germany
Komarov Institute of Russian Academy of Science, Prof. Popov Str., 2, St. Petersburg, 197376, Russia
Herbarium, Library, Art & Archives, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AE, UK
Central National Herbarium, Botanical Survey of India, Acharya Jagadish Chandra Bose Indian Botanic Garden, Howrah 711103, West Bengal, India
Kuen Shum Pang
Agriculture, Fisheries and Conservation Department, Cheung Sha Wan Government Offices, 303 Cheung Sha Wan Road, Kowloon, Hong Kong