Molecular phylogenetics of Micromeles (Rosaceae: Maleae): implications for taxonomy

Background Micromeles Decne., belonging to the tribe Maleae of the family Rosaceae, has a complicated taxonomic history. It was either recognized as a distinct genus in the broad sense ( Micromeles s.l. ), or in the restricted sense ( Micromeles s.s. ), or even merged within the genus Aria , Pyrus , or Sorbus . The present study aims to clear the confusions of the taxonomic identity of Micromeles using both plastid and nuclear datasets. Results Both phylogenetic trees based on plastome and ITS datasets strongly support the monophyly of Micromeles s.l. However, Micromeles s.s. and the other five small genera, including Alniaria , Dunnaria , Griffitharia , Thomsonaria , and Wilsonaria are non-monophyletic and are synonymized under Micromeles s.l. Pleiosorbus has been synonymized under Micromeles s.l. following Lu and Ku, and Mezhenska et al. based on their morphological similarities. Two new combinations at the infraspecific level are proposed here. Conclusions This study approves of the adoption of the broad sense of Micromeles based on both phylogenetic and morphological evidence.