ABSTRACT
Stichorkis gibbosa is a rare orchid species of the tribe Malaxideae mainly distributed in tropical Asia. This is the only species of the genus Stichorkis Thouars which has been reported to occur in China. Despite the importance of this genus, previous molecular studies based on few markers have resulted in limited phylogenetic resolution. With the decline of habitats, the wild population of S. gibbosa has decreased in recent years. In this study, we first reported the complete chloroplast (cp) genome of S. gibbosa. The entire cp genome was determined to be 158,056 bp in length with overall GC content of 36.9%, containing a pair of inverted repeat regions (IRs) of 27,006 bp, separated by a large single-copy (LSC, 86,280 bp) and a small single-copy (SSC, 17,764 bp). A total of 133 unique genes were annotated, including 87 protein-coding genes, 38 tRNA genes, and eight rRNA genes. The phylogenetic tree indicated that S. gibbosa was a sister group of the genus Oberonia and the epiphytic Liparis alliance with strong support.
ABSTRACT
An investigation of a questionable orchid led to the discovery of a new genus and species Thuniopsis cleistogama, endemic to Yunnan province, China. It is characterized by having a subglobose corm, a spike-like (racemose) inflorescence, half opened and spurless flowers, a collar-shaped stigma and subglobose capsules. Based on DNA sequence data from three gene regions (nuclear ribosomal ITS, chloroplast matK and trnL), we investigated its phylogenetic position within the tribe Arethuseae. Phylogenies using maximum likelihood and Bayesian inference support the recognition of Thuniopsis as a distinct genus, and suggest its close relationship to the genera Bletilla, Dilochia, and Thunia. The new genus is circumscribed and a description and illustrations of the new species are provided. The phylogenetic relationships among the genera in Arethuseae are accessed. Moreover, our phylogeny also shed light on the phylogenetic positions of several genera which, to date, remain uncertain.
