New insights into the phylogeny of Sinocarum (Apiaceae, Apioideae) based on morphological and molecular data

Abstract

Sinocarum is a Sino-Himalayan endemic genus of Apiaceae and distributed in high-elevations from Nepal to SW China. In this study, morphological characteristics were combined with nuclear internal transcribed spacer (ITS) and two chloroplast DNA (cpDNA) intron sequences (rpl16 and rps16) to determine the phylogenetic placement of Sinocarum and the infrageneric relationships between five Sinocarum species. The results confirmed that Sinocarum was a polyphyletic group separated into two clades, Acronema and East Asia clades. S. coloratum, the generic type of Sinocarum, S. cruciatum, S. vaginatum and S. filicinum are in the Acronema clade. Among them, the first three species are clustered into a subclade and are closely related to the genus Acronema. While S. filicinum has a close affinity with Meeboldia. S. schizopetalum did not ally with its congeners we collected and is allied closely with members of the distantly related East Asia clade. In addition, the fruit of the Acronema clade Sinocarum species is usually oblong-ovoid or ovoid, and the pollen is super-rectangular, while the Sinocarum species in the East Asia clade have broad-ovoid fruit and sub-rhomboidal pollen. This study has furnished cumulative evidence to reduce phylogenetic uncertainty and provide a more comprehensive description of the plant morphology, fruit morphology and anatomy, and pollen morphology of these five Chinese Sinocarum species.