Wednesday, May 17, 2017

[Botany • 2017] Danxiaorchis yangii the Second Species of Danxiaorchis (Orchidaceae: Epidendroideae), from Jinggangshan National Nature Reserve, Jiangxi, China


Danxiaorchis yangii   B. Y. Yang et Bo Li


Abstract

Danxiaorchis yangii (Calypsoinae, Epidendreae, Epidendroideae), a holomycotrophic new species from Jinggangshan National Nature Reserve, western Jiangxi, eastern of China, is here illustrated and described based on both morphological and phylogenetic evidences. The new species can be easily distinguished from D. singchiana by its much smaller flowers and larger Y-shaped callus adaxially bearing a additional obovoid appendage, and by its four pollinia narrowly elliptic in shape and equal in size.

Keywords: Danxiaorchis, Jinggangshan Mountains, Jiangxi orchids, phylogenetic analysis, Monocots


  

FIGURE 3. Morphology of Danxiaorchis yangii B. Y. Yang et Bo Li, sp. nov. (A–I).
A. Flowering in nature habitat and rhizome (showed in the black circle); B. Front view of a flower; C. Bottom view of labellum, showing two sacs; D. Front view of the Y-shaped appendage of labellum; E. Upper view of a labellum with column; F. Side view of a labellum with column; G. Side view of the Y-shaped appendage of the labellum; H. Capsule; I, Pollinarium.
 Scale bars: B = 1 cm; C, D, E = 5 mm; F, G, I = 1 mm; H = 1 cm.  DOI:  10.11646/phytotaxa.306.4.5

Taxonomy
 Danxiaorchis yangii B. Y. Yang et Bo Li, sp. nov. 

 Diagnosis:— Danxiaorchis yangii obviously differs from D. singchiana in its Y-shaped callus adaxially bearing a remarkable obovoid appendage, and in its four pollinia narrowly elliptic in shape and equal in size.

Etymology:— The specific epithet refers to the family name of the first author, Pro. Boyun Yang, who devotes himself to the conservation of orchids biodiversity in Jiangxi Province, China.

Distribution and habitat:— To date, the species was discovered only from Jinggangshan National Nature Reserve in western Jiangxi, eastern of China. It occurs in nearly the same longitude as D. singchiana but in higher latitude (Fig. 4). D. yangii frequently grows at the margin of subtropical evergreen broad-leaved forest, under mixed shrubs and bamboo forest, in wet places at elevations of 360 m a.s.l.

Discussion:
 With the characteristic large Y-shaped appendage on its labellum, D. yangii is a certainty member of the genus Danxiaorchis, and it was well supported by molecular phylogenetic analyses based on combined datasets of ITS and matK (Fig. 1). After thorough morphological comparison between D. yangii and D. singchiana, we found that D. yangii can be easily distinguished from D. singchiana in many aspects (Fig. 3). Superficially the plants of i. yangii are shorter than those of D. singchiana, and its flowers are much smaller, whereas its Y-shaped appendages are much larger than those of D. singchiana. Besides, the adaxial side of the Y-shaped appendages in D. singchiana is flat or slightly raised, while in D. yangii, the adaxial side additionally bears a remarkable obovoid appendage with its size ca. 3.0–3.5 mm in diameter (Fig. 3 G vs. b). Furthermore, there is an essential difference between D. yangii and D. singchiana: the four pollinia of D. yangii are narrowly elliptic in shape and equal in size, while those of D. singchiana are subobovoid-globose with two pollinia unequal in size in each pair (Fig. 3 I vs. c). Consequently, we found out that D. yangii can be treated as a distinct species, which is the second species in Danxiaorchis.


Boyun Yang, Shihe Xiao, Yawen Jiang, Huolin Luo, Dongjin Xiong, Junwen Zhai and Bo Li. 2017. Danxiaorchis yangii sp. nov. (Orchidaceae: Epidendroideae), the Second Species of DanxiaorchisPhytotaxa. 306(4); 287–295.  DOI:  10.11646/phytotaxa.306.4.5


Danxiaorchis (J.W. Zhai, F.W. Xing et Z.J. Liu in Zhai et al. 2013)
Zhai, J.W., Zhang, G.Q., Chen, L.J., Xiao, X.J., Liu, K.W., Tsai, W.C., Hsiao, Y.Y., Tian, H.Z., Zhu, J.Q., Wang, M.N., Wang, F.G., Xing, F.W. and Liu, Z.J. 2013. A new orchid genus, Danxiaorchis, and phylogenetic analysis of the tribe Calypsoeae. PloS One. 8: e60371. DOI: 10.1371/journal.pone.0060371

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