Evolutionary relationships and diversification of Stachyuraceae based on sequences of four chloroplast markers and the nuclear ribosomal ITS region

Abstract

Stachyuraceae consist of a single genus Stachyurus with about ten species endemic to eastern Asia. The family was recently shown to be sister to the western North American Crossosomataceae. The phylogeny of Stachyuraceae and its relatives was reconstructed based on sequences of four chloroplast DNA regions (trnL intron and adjacent trnL‐trnF spacer, rps16 intron, ndhF gene, trnS‐trnG‐trnG region) and the nuclear ribosomal ITS region. The monophyly of Stachyurus was strongly supported. The divergence time between Stachyuraceae and Crossosomataceae was estimated to be 68.25 ± 10.36 million years ago (MYA) using the penalized likelihood method based on rbcL sequences data with fossil calibration. Stachyurus sigeyosii was previously synonymized as S. himalaicus, but our analysis shows that it is sister to the morphologically highly distinct S. praecox from Japan and does not form a clade with S. himalaicus.