This taxon name is current. The available references for this name are:
Usnea arida Motyka is a taxonomic synonym.
Reason: See P.M. McCarthy in Checklist of the Lichens of Australia and its Island Territories: http://www.anbg.gov.au/abrs/lichenlist/introduction.html [accessed 12/05/2015]
See also: A longer explanation of these and other terms in our Plant Names Primer.
A taxon name which is no longer current will retain its ‘Threatened’ status until publication of the next Wildlife Conservation (Rare Flora) Notice.