Reassessment of rust fungi on weeping willows in the <scp>A</scp> mericas and description of <i> <scp>M</scp> elampsora ferrinii </i> sp. nov.

Abstract

Rust fungi in the genus M elampsora usually cause disease on hosts in the Salicaceae. Identification of M elampsora species is often complicated due to few differences in spore morphology and little publicly available comparative sequence data. Weeping willow trees (primarily S alix babylonica and its hybrids) have been reported to be infected by 11 M elampsora species; however, most of these records are based on morphological characterization. New collections of rust fungi on weeping willows from the central USA were analysed using a combination of morphology, ITS and LSU r DNA sequencing, and host data to determine that they represent an undescribed rust fungus, M elampsora ferrinii sp. nov. Additional studies of herbarium material revealed that M . ferrinii has occasionally been collected but identified as M . epitea . In addition to N orth A merica, M . ferrinii is also present in S outh A merica and has been infecting weeping willows there since at least the 1990s.