Weeding the nettles V: Taxonomic and phylogenetic studies of the eastern Asian species Urtica thunbergiana Sieb. & Zucc. (Urticaceae)

Abstract

Urtica L. (Urticaceae) is a subcosmopolitan genus, which is also common throughout Asia. Taxon differentiation in the Asian Urtica species is difficult due to the limited diversity of taxonomically useful characters combined with a range of phenotypic variation. The present study investigates the species Urtica thunbergiana Sieb. & Zucc. (incl. U. laetevirens) from eastern Asia based on herbarium collections, including most of the type specimens. The delimitation of U. thunbergiana is expanded to include all three currently recognized subspecies of U. laetevirens Maxim. Also, one newly infraspecific taxon is described from Taiwan. Based on our revision, the recognition of a total of four subspecies of Urtica thunbergiana is proposed: subsp. thunbergiana, subsp. dentata (Hand.-Mazz.) K.Becker & Weigend, subsp. silvatica (Hand.-Mazz.) K.Becker & Weigend, and subsp. perserrata, subspec. nov. The systematic re-arrangements are based on morphological analyses and a highly resolved phylogeny based on the molecular markers ITS1–5.8S–ITS2, psbA–trnH, trnL–trnF and trnS–trnG.