Fissurina

The genus was circumscribed by the French botanist Antoine Laurent Apollinaire Fée in an 1825 publication.[3] Some later authors preferred to use the name Fissurina to describe infrageneric (i.e., below genus level) groups of the genus Graphis, such as Edvard Vainio in 1921 who used it as a subgenus,[4] and Alexander Zahlbruckner (1923)[5] and Karl Redinger (1935),[6] who used the name for sections.

Fissurina is in the family Graphidaceae.[7] In 2018,[8] Kraichak and colleagues, using a "temporal phylogenetic" approach to identify temporal bands for specific taxonomic ranks, proposed placing Fissurina as the type genus of Fissurinaceae, a family originally proposed by Brendan P. Hodkinson in 2012.[9] This taxonomic proposal was rejected by Robert Lücking in a critical 2019 review of the temporal method for the classification of lichen-forming fungi, using this specific example to highlight several drawbacks of this approach.[10]

Fissurina is characterized by fissurine ascocarps (i.e., having a fissured or slit-like disc), poorly developed and non-carbonized or weakly carbonized exciples, and 1-8 spored asci that make thick-walled, trans-septate or muriform hyaline ascospores often with a halo. Acanthothecis is a similar genus with warty paraphyses and periphysoids but can be differentiated from Fissurina by the cylindrical spore locules without a thick jelly-like spore wall. Graphis differs from Fissurina by its carbonized, well-developed exciple (labia) and ascospores without a halo.[11]