Paraholcoglossum and Tsiorchis, two new orchid genera established by molecular and morphological analyses of the Holcoglossum alliance.
BACKGROUND
Holcoglossum is a small orchid genus of 12 species ranging from SW China to Thailand and NE India. Although molecular and morphological analyses have been performed to establish the phylogenetic relationships within this genus, the interspecific relations and its relations with allied genera, such as Rhynchostylis, Aerides and Vanda, remain unclear.


RESULTS
In addition to morphological analysis, maximum parsimony, maximum likelihood, and Bayesian inference analyses were performed based on fragments of the nuclear ITS and chloroplast trnL-F and matK genes of 31 taxa (15 Holcoglossum, 14 Aeridinae, 2 outgroups) representing all major clades of the Holcoglossum alliance. The results suggest that Holcoglossum is triphyletic, comprising three clades: the Holcoglossum clade, its sister clade, and a distant clade more closely related to Rhynchostylis, Aerides, and Vanda than to the Holcoglossum clade. The Holcoglossum clade is further divided into three subclades; the genetic distances between these three subclades also support this delimitation. The molecular conclusion is consistent with their distinct morphological characters.


CONCLUSIONS
We propose that the latter two clades comprise two new genera, Paraholcoglossum and Tsiorchis, and Holcoglossum clade divides into three sections. In addition, a new section, Holcoglossum sect. Nujiangensia, and a new species, Holcoglossum linearifolium, are proposed. Some new combinations are made, and a new scheme is provided for the classification of all species of Holcoglossum, Paraholcoglossum, and Tsiorchis.
Shenzhen Key Laboratory for Orchid Conservation and Utilization, The National Orchid Conservation Center of China and The Orchid Conservation and Research Center of Shenzhen, Shenzhen, China. liuzj@sinicaorchid.org
Zhong-Jian
ZJ
Liu
Li-Jun
LJ
Chen
Sing-Chi
SC
Chen
Jing
J
Cai
Wen-Chieh
WC
Tsai
Yu-Yun
YY
Hsiao
Wen-Hui
WH
Rao
Xue-Yong
XY
Ma
Guo-Qiang
GQ
Zhang
D001499:Bayes Theorem; D021901:DNA, Intergenic / Q000235:genetics; D061125:Genes, Chloroplast / Q000235:genetics; D016013:Likelihood Functions; D029595:Orchidaceae / Q000033:anatomy & histology / Q000145:classification* / Q000235:genetics*; D010802:Phylogeny; D017422:Sequence Analysis, DNA
D021901:DNA, Intergenic