Molecular phylogeny of Strobilanthes (Acanthaceae) from the northern Western Ghats of India: phylogenetic relationships and implications for systematics and biogeography

Abstract

Strobilanthes is the second largest genus of Acanthaceae and grows naturally in the tropical regions of Asia. India is a centre of diversity for this genus in the Western Ghats and the northern/northeastern regions of India have approximately 150 species. In this study, ten Strobilanthes species, including one unpublished species (Strobilanthes sp. ‘137262') and one newly discovered variety from the northern Western Ghats were examined to understand their evolutionary history using molecular phylogenetics. Nuclear ribosomal internal transcribed spacer (nrITS), three chloroplast DNA (cpDNA) sequences trnL, rbcL, matK and one mitochondrial DNA (mtDNA) sequence matR were sequenced. Overall, the northern Western Ghats species have a close relationship with other peninsular Indian species. The results indicate that Strobilanthes has repeated independent colonizations in the northern Western Ghats from southern Western Ghats or from northeastern India. There are also dispersals out of the Western Ghats into Southeast Asia. This work provides the first phylogenetic understanding of the speciose genus Strobilanthes from the northern Western Ghats and will be further extended to unravel the evolution of this genus in the entire Indian sub-continent.