Notes on Caloplaca allanii Zahlbr. (Teloschistaceae) a poorly known West Auckland, North Island, New Zealand endemic

After a lapse of 81 years we report the rediscovery of Caloplaca allanii (Teloschistaceae), a lichen previously known only from the type collection. The species appears to be endemic to the Waitakere Ranges coastline west of Auckland, North Island, New Zealand. A revised description of the species based on fresh material is provided, and we expand the distribution of the species as well as describing its habitats and associated species. A table and key to the saxicolous, coastal Caloplaca of the Waitakere Ranges is also provided. As a narrow-range endemic, with apparently very specific habitat requirements, C. allanii is a naturally uncommon, biologically sparse species. Nevertheless because of the small total area of occupancy, we assess C. allanii as ‘Threatened’/‘Nationally Critical’ using the New Zealand Threat Classification System.