Phylogenetic relationships in the Pterygiella complex (Orobanchaceae) inferred from molecular and morphological evidence

The Pterygiella complex, i.e. Pterygiella, Phtheirospermum, Pseudobartsia and Xizangia, is controversial in terms of both its relationships and taxonomic status. The genera of the complex are all species‐poor and endemic to eastern Asia. In this study, we sampled all taxa in the complex for seven genic regions [atpB‐rbcL, atpH‐I, psbA‐trnH, rpl16 intron, trnL‐F, trnS‐G and internal transcribed spacer (ITS)], which were analysed separately and in combination. We examined capsule and seed morphology of these genera using scanning electron microscopy (SEM). Our results indicate that the complex is polyphyletic and comprises two clades. The first, designated ‘Pterygiella complex I’, includes only Phtheirospermum japonicum. This clade is uniquely diagnosed by its papery yellow capsule and reticulate secondary thickening on the seed coat. The second clade, ‘Pterygiella complex II’, includes Phtheirospermum tenuisectum, P. parishii, P. muliense, Pseudobartsia, Xizangia and Pterygiella. These taxa share a coriaceous capsule. Pterygiella is monophyletic and is characterized by eglandular, unicellular, pilose hairs on the capsule and hook‐like protuberances on the horizontal ridges of the striate or reticulate seed coat. Excluding P. japonicum, the remaining taxa of Phtheirospermum cluster together and are sister to Pterygiella. Xizangia bartschioides and Pseudobartsia yunnanensis are separated from Pterygiella and Phtheirospermum, respectively, and are supported as genera by molecular and morphological evidence. © 2013 The Linnean Society of London