Combination of Sanger and target-enrichment markers supports revised generic delimitation in the problematic ‘Urera clade’ of the nettle family (Urticaceae)

Wells, Tom; Maurin, Olivier; Dodsworth, Steven; Friis, Ib; Cowan, Robyn; Epitawalage, Niroshini; Brewer, Grace; Forest, Felix; Baker, William J.; Monro, Alexandre K.

Combination of Sanger and target-enrichment markers supports revised generic delimitation in the problematic ‘Urera clade’ of the nettle family (Urticaceae)

Resource type

Journal article

Creator (person)

Wells, Tom

Maurin, Olivier

Dodsworth, Steven

Friis, Ib

Cowan, Robyn

Epitawalage, Niroshini

Brewer, Grace

Forest, Felix

Baker, William J.

Monro, Alexandre K.

Date published

May 2021

Abstract

Urera Gaudich, s.l. is a pantropical genus comprising c. 35 species of trees, shrubs, and vines. It has a long history of taxonomic uncertainty, and is repeatedly recovered as polyphyletic within a poorly resolved complex of genera in the Urticeae tribe of the nettle family (Urticaceae). To provide generic delimitations concordant with evolutionary history, we use increased taxonomic and genomic sampling to investigate phylogenetic relationships among Urera and associated genera. A cost-effective two-tier genome-sampling approach provides good phylogenetic resolution by using (i) a taxon-dense sample of Sanger sequence data from two barcoding regions to recover clades of putative generic rank, and (ii) a genome-dense sample of target-enrichment data for a subset of representative species from each well-supported clade to resolve relationships among them. The results confirm the polyphyly of Urera s.l. with respect to the morphologically distinct genera Obetia, Poikilospermum and Touchardia. Afrotropic members of Urera s.l. are recovered in a clade sister to the xerophytic African shrubs Obetia; and Hawaiian ones with Touchardia, also from Hawaii. Combined with distinctive morphological differences between Neotropical and African members of Urera s.l., these results lead us to resurrect the previously synonymised name Scepocarpus Wedd. for the latter. The new species epiphet Touchardia oahuensis T.Wells & A.K. Monro is offered as a replacement name for Touchardia glabra non H.St.John, and subgenera are created within Urera s.s. to account for the two morphologically distinct Neotropical clades. This new classification minimises taxonomic and nomenclatural disruption, while more accurately reflecting evolutionary relationships within the group.