title: A new isidiate species of Arthonia (Ascomycota: Arthoniaceae) from Costa Rica.
abstract: The new corticolous species Arthonia isidiata is described from the Pacific lowlands of Costa Rica. A. isidiata is characterized by minute, cylindrical to coralloid isidia produced on the thallus surface. The species currently is known only from the type locality in Corcovado National Park, where it occurs abundantly in the coastal rainforest around Sirena Biological Station.
authors.affiliation: Institute of Botany, Karl-Franzens-University Graz, 8010 Graz, Austria.
authors.forename: Martin
authors.initials: M
authors.lastname: Grube
authors.forename: Robert
authors.initials: R
authors.lastname: Lücking
authors.forename: Loengrin
authors.initials: L
authors.lastname: Umaña-Tenorio