The identity of Lecanora ecorticata has been uncertain due to conflicting reports of the presence of zeorin and the loss of the holotype. Phylogenetic analysis suggests that the species probably belongs in Ramalinaceae, where it is the first leprose species reported. Zeorin was found to be absent in recently collected material of L. ecorticata, including specimens from the type locality, and the report of zeorin in the lost holotype is considered to be due to contamination. A new genus, Lithocalla, is erected to accommodate L. ecorticata and a second closely related species, that occurs in the Falkland Islands, is newly combined as Lithocalla malouina. A lectotype is selected for L. ecorticata. Lithocalla is characterized by a leprose thallus containing usnic acid with fatty acids and terpenoids, but no zeorin; ascomata and conidiomata are unknown.

A standardized morphological terminology and descriptive scheme for the sterile asexually reproducing genus Lepraria s. lat. is presented. The contribution includes observations on development and ontogeny of morphological structures and is extensively illustrated with scanning electron and light micrographs. Lepraria has long been considered to be devoid of morphological characters, however the results of extensive micro- and macro-morphological studies strongly refute this hypothesis. The morphological structures of the thallus are defined and described based on their varying degrees of complexity. Thalline morphological variability in the group is categorized into two major types that are further subdivided into six subtypes. Each subtype is described and an artifical key to the subtypes is provided.

Lepraria granulata Slavíková, a new species from Eastern and Central Europe, is described. According to its morphology, ITS sequence and ecology, it belongs to the L. neglecta core group. Lepraria granulata is characterized by producing atranorin and two, so far unidentified, fatty acids (‘granulata unknown 1 & 2’) and phylogenetic analyses show that it is clearly distinguished from previously known species. Two additional taxa, provisionally named Lepraria sp. G and Lepraria sp. BG, are also discussed. According to their morphology and ITS sequences, they also belong to the L. neglecta group. Lepraria sp. G is sister to L. granulata whereas Lepraria sp. BG is basal and well separated from all taxa so far known in the group. Their taxonomic status is not yet entirely clear.

Three new species of Lepraria, L. celata, L. humida, and L. sylvicola, are described from Europe. They each possess a finely granular unstratified thallus containing fatty acids and atranorin, but can be distinguished from each other by the type of fatty acids present and by their ecology. Anthraquinones are present in subthalline hyphae of L. humida and L. sylvicola, and are also reported for L. atlantica. Toensbergianic acid can be produced by L. jackii as a minor compound. A key is presented to species of Lepraria containing fatty acids and atranorin as major substances.

Lepraria aurescens and Lepraria pulchra are described as new from bark in Thailand; both contain thamnolic acid, but differ in thallus form and colour.