Marambio (Seymour) Island is located in the James Ross Archipelago east of the Antarctic Peninsula. Although several research groups have carried out studies on the biodiversity on the island for decades, surveys of bryophytes have not been developed. That is why there are currently only six species of mosses recorded in the northern part of the island. During the 2021–2022 summer Antarctic field trip, 15 mosses species were surveyed in Marambio Island. Of the total number of collected species, nine are reported for the first time for Marambio Island. For the remaining four species, their distributions are now expanded to Marambio Island.

Located east of the Antarctic Peninsula, Cockburn Island is a small island in the James Ross Archipelago. Studies of mosses on the island are scarce. The oldest studies date from the first half of the nineteenth century to the most recent in 1993. The number of records of mosses is very small due to the difficulty of accessing the area. Here, we report an updated composition of the moss flora of the plateau, in which four new records have been found: Bryoerythrophyllum antarcticum, Ceratodon purpureus, Pohlia wilsonii and Schistidium lewis-smithii. The occurrence of these species on the plateau shows that the ranges of these species have expanded from the Antarctic Peninsula to the east. This collection highlights the need for further research into the dynamics of moss flora in the context of climate change.

The foliose lichens Pseudocyphellaria pilosella and P. piloselloides are characterized by a cyanobacterial photobiont, a tomentose upper surface, a yellow medulla and yellow pseudocyphellae. The latter species has long been recognized as the sorediate counterpart of the former. The morphological, anatomical, chemical, and molecular analyses performed for this study support their treatment as a single species.

A preliminary study of the Lecanora dispersa group in Argentina is presented. Two species (L. dispersa and L. hagenii) have been previously recorded and their known distribution is extended, one species (L. semipallida) is a new record from Argentina, and five taxa (L. flowersiana, L. persimilis L. torrida, L. wetmorei and L. zosterae var. zosterae) are reported for the first time from South America. Three species (L. albescens, L. crenulata and L. populicola) previously recorded for Argentina have not been confirmed as occurring in this country. Lecanora aff. fugiens is also treated and compared to the related species. The morphology, anatomy, secondary metabolites, distribution and ecology of the nine studied taxa are described and discussed, and a key to the taxa is included.

Hysterium graphideum Speg. is proposed as a synonym of Gloniella graphidoidea Rehm. During the study of the types of both names, the presence of algae associated with the fungal hyphae was found. The main morphological and anatomical characters, and the ecology of the species are presented.

The corticolous lichen Lecanora subviridis de la Rosa & Messuti is described from temperate forests in south-western Argentina as new to science. It differs from other species of Lecanora occurring on bark and wood by containing usnic or isousnic acid. The relationships with the other taxa are discussed.

Chapsa rubropruinosa Messuti & Codesal collected in Argentina is described as new to science. The species is characterized by a thin thallus, apothecia with a pigmented disc, and transversely septate, hyaline, non-amyloid to faintly amyloid ascospores with thin cell walls. Chapsa minor is recorded for the first time from South America. The new combination Topeliopsis lomatiae (Messuti, Lumbsch & Vězda) Messuti & Mangold is proposed.

Thelotremoid lichens (Ostropales, Ascomycota) with a trentepohlioid photobiont in Tierra del Fuego, the Falkland Islands, the South Island of New Zealand, and subpolar islands of the southern Hemisphere are studied. Twenty-five species are accepted, with three species described as new to science: Melanotopelia blepharostoma Lumbsch & Divakar, Topeliopsis athallina Lumbsch & Mangold and Topeliopsis patagonica Mangold & Lumbsch. The new combination Topeliopsis novae-zelandiae (Szatala) Lumbsch & Mangold is proposed.

%The new saxicolous species P. clercii Messuti & A. W. Archer is described. The following two taxa are reported for the first time from Africa: P. petrophyes C. Knight and P. subventosa var. deficiens A. W. Archer & Elix. A brief description of each species is given together with notes on their chemistry, distribution, ecology and taxonomy.

After revising the order Pertusariales in Tierra del Fuego (Messuti & Vobis 2002), Teuvo Ahti drew my attention to some nomenclatural problems concerning Pertusaria pachythallina (Räsänen) Messuti. This name was based on Pertusaria grisea var. pachythallina Räsänen. However, the new combination was invalidly published since the page of publication was not indicated (Art. 33.3, Ex 5 ICBN 2000) and the lectotypification originally performed by Lamb (in herb.) did not meet the Code requirements (Art. 7.11). The correct nomenclature and typification are indicated below.

The new species, Pertusaria huanicola Messuti & A. W. Archer (Pertusariaceae, Ascomycota), is described. It is distinguished from Pertusaria phlyctaenula Nyl., P. subambigens Dibben and P. suboculata Brodo & Dibben by the chemistry and the number of ascospores per ascus. The new species is known only from Valdivian rainforest in south-western Argentina.

Two new species of Mycobilimbia are described and compared with other members of the genus: Mycobilimbia australis Kantvilas & Messuti from austral, cool to cold temperate regions, and Mycobilimbia meridionalis Kantvilas from Tasmania. Two additional, superficially similar species that are widespread in the Northern Hemisphere, M. hypnorum (Lib.) Kalb & Hafellner and Bilimbia lobulata (Sommerf.) Hafellner & Coppins, are recorded from Tasmania for the first time.

Eight species of the lichen genus Pertusaria (Pertusariaceae) are reported from the Juan Fernández Archipelago (Chile). Pertusaria fernandeziana is described as a new species and two species, Pertusaria phlyctaenula Nyl. and Pertusaria dehiscens Müll. Arg., are recorded for the first time from the archipelago. Range extensions of the known distribution within the archipelago are reported for Pertusaria hadrocarpa Zahlbr., Pertusaria melanospora Nyl., Pertusaria pachythallina (Räsänen) Messuti, Pertusaria papillulata Nyl., and Pertusaria velata (Turner) Nyl. Pertusaria polycarpa Kremp. var. monospora Zahlbr. is reduced to synonymy with Pertusaria papillulata and Pertusaria chilena Zahlbr. is synonymized with Pertusaria velata. A diagnostic key, descriptions, and illustrations of the species are presented with data on their habitat ecology and distribution.

A new corticolous species belonging to the lichen family Pertusariaceae, Pertusaria grassiae Messuti & A.W. Archer, is described from Tucumán Province, Argentina. It is characterized by disciform apothecia covered by a white to greyish white pruina, single-spored asci, ellipsoid and double-walled ascospores and the presence of atranorin.

The new species Ochrolechia splendens Lumbsch and Messuti, is described from Mexico, south-western North America, where it occurs on exposed siliceous rocks. It is characterized by relatively large apothecia with entire margins, the presence of the gyrophoric acid chemosyndrome in the thallus and apothecial disc and the presence of lichexanthone as major components.

Chroodiscus lomatiae Messuti, Lumbsch & Vezda is described as new to science. This southern South American species belongs to the family Thelotremataceae. It is characterized by fusiform, hyaline, small, thin-walled ascospores, exfoliating, chroodiscoid apothecia, and the presence of lecanoric acid.

The Coccotremataceae is a small family including two genera: Coccotrema with a crustose, granulate to verrucose thallus and Lepolichen with terete lobes and rhizines. The generic concept based on this morphological difference was re-evaluated using three molecular markers, mt SSU rDNA, nu LSU rDNA, and the nu ITS region. The analysis of the ITS region does not provide sufficient resolution within the Coccotremataceae, while the other two data sets contradict the current generic concept. The mt SSU and nu LSU data sets and the combined analysis of the two data sets all place Lepolichen within Coccotrema. However, an alternative topology with monophyletic Coccotrema cannot be rejected when the ITS data set is included in the combined analyses. This shortcoming of the ITS data set can be overcome by the combined analysis of all three data sets, where monophyletic Coccotrema can be rejected using parametric bootstrapping, as in the mt SSU and nu LSU data sets and combination thereof. It is proposed to reduce Lepolichen into synonymy with Coccotrema. The correct name for the only species previously placed in Lepolichen is Coccotrema coccophontm (Mont.) I. Schmitt, Messuti & Lumbsch.

Species of Gloniella, Glonium and Gloniopsis from southern South America were studied. A new fungus Glonium colihuae sp. nov., with hysterothecia is described from Argentina, Patagonia; Glonium chusqueae is synonymized with Gloniella typhae; Gloniopsis argentinensis and Glonium costesi are validated, and some comments on the taxonomy and occurrence of Gloniopsis araucana, G. praelonga, Glonium abbreviatum and G. cumingii are presented.