Molecular phylogeny resolves a taxonomic misunderstanding and places Geisleria close to Absconditella s. str. (Ostropales : Stictidaceae).

The phylogenetic position of the genus and its type species was reconstructed using sequence data of the mitochondrial small subunit (mtSSU), the nuclear large subunit rDNA (nuLSU) and the first subunit of the RNA polymerase ( ). The species, previously classified in (Eurotiomycetes) and (Dothideomycetes), is sister to the type of the genus , , and nested within the genera and combined (which also includes the lichenized ). At first glance it appears to be a further example of parallel evolution of perithecioid ascomata within (Lecanoromycetes: ), besides and , adding to the growing list of perithecioid forms nested within apothecioid lineages in Ostropomycetidae, and specifically , with other examples known from (several genera), ( ), and . However, revision of type material collected by Nitschke revealed that the species actually develops typical apothecia with a narrowly exposed disc. We conclude that was erroneously considered a pyrenocarpous taxon, because in dry conditions the apothecia are closed and not recognizable as such. The species usually grows on unstable soil and therefore often only develops young, more or less closed ascomata (yet with mature ascospores), and has also been confused with the superficially similar , in which the ascomata remain closed even when mature. has so far only been known as a rarely reported pioneer species from loamy soils in Europe and North America. Here it is reported to occur abundantly on lateritic soils in subtropical Brazil, suggesting that it is cosmopolitan and possibly common, but much overlooked.

Funder

Funder name	Awards
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Brazil
National Science Foundation, United States	DEB-1025861
Vetenskapsrådet, Sweden	VR 621-2006-3760 - VR 621-2009-537
Stichting Hugo de Vries-Fonds