- Lichenes Neotropici Fascikel XVI (No. 628–650) (2017)
- Fascicle XVI of the exsiccate "K. KALB & A. APTROOT: LICHENES NEOTROPICI" (new name for "K. KALB: LICHENES NEOTROPIC" from fascicle XVI onwards) with 23 lichen specimens (No. 628–650) from Brazil, Chile, Dominican Republic, Ecuador, Kenya, Peru and Venezuela is distributed. Three species are described as new, namely Lopadium subcoralloideum Aptroot & Kalb, Lecanactis caceresiana Kalb & Aptroot and Rhizocarpon sipmanianum Kalb & Aptroot. The holotypes of the new species are deposited at Universidade Federal de Mato Grosso do Sul (UFMS). Range extensions are reported for Hypocenomyce tinderreyensis (new to the Neo-tropics; so far only known from Australia, but apparently austral), Ocellularia baorucensis (new to Brazil), Physcidia striata (recently described from Rondônia and the Venezuelean Amazon, and subsequently reported from Amapá and Brazilian Amazonas. The collection from Brazil/Mato Grosso do Sul represents a major range extension to the South), Tephromela campestricola (new to the Neotropics; not different in any way from European material) and Xanthoparmelia arvidssonii (new to Venezuela).
- A new synonym and a new species in the lichen genus Dirinaria (2019)
- A restudy of two lichen taxa described by de Lesdain from Cuba revealed one later synonym of Dirinaria purpurascens and a new species, Dirinaria flavida, the primary species of D. flava.
- New or otherwise interesting lichens. VII, including a world key to the lichen genus Heiomasia (2020)
- Eight species new to science are described, Allographa grandis from Cameroon which is distinguished by its very large ascomata, richly muriform, large ascospores and an inspersed hymenium (type B); Bapalmuia microspora from Malaysia which differs from B. consanguinea in having shorter and broader ascospores and a granular thallus; Diorygma cameroonense from Cameroon which differs from D. sticticum in having larger ascospores with more septa; Glyphis frischiana which is similar to G. atrofusca but differs in producing secondary lichen compounds, the first species in Glyphis in doing so. Two new species are added to the genus Heiomasia, viz. H. annamariae from Malaysia, which differs from H. sipmanii in producing the stictic acid aggr. and H. siamensis from Thailand, distinguished from H. sipmanii in containing hypoprotocetraric acid as a major metabolite. The published chemistry of several species of Heiomasia is revised and a new substance, heiomaseic acid, with relative Rf-values 5/19/8, is demonstrated for H. seaveyorum, H. siamensis and H. sipmanii. A world-wide key to the known species of Heiomasia is presented. Myriotrema squamiferum, a fertile species from Malaysia, is distinguished from M. frondosolucens by lacking lichexanthone. As there are conflicting literature data concerning Ocellularia crocea, the type specimen was investigated and the results are reported. Ocellularia macrocrocea, a related species from Malaysia, differs from O. rubropolydiscus in lacking the red pigment covering the disc of the ascomata and in having a broad stump-shaped columella. A revised chemistry for Ocellularia tanii, a new record for Sarawak, is also given. A table of Rfvalues and scans of relevant TLC runs facilitate the interpretation of the spots occurring on TLC plates of Graphidaceae.
- New or otherwise interesting lichens. VIII. Eight new species, mainly from the family Graphidaceae, and two new records (2020)
- Eight new lichen species are described from South America, Malaysia and Thailand, viz. Chapsa canaimae from Venezuela, which differs from C. alborosella in having distictly smaller ascospores with less septa, Dirinaria hypoleuca from Thailand, which differs from the isidiate D. papillulifera in having a whitish lower surface, Myriotrema robertianum from Brazil, which differs from M. viride in having an inspersed hymenium, Myriotrema subzollingeri from Brazil, which differs from M. glauculum in having brown ascospores, Ocellularia jutaratiae from Brazil, which differs from O. crocea in having ascomata with a fissured margin, Ocellularia subnatashae from Brazil, which differs from O. natashae in lacking hirtifructic and conhirtifructic acids and in having smaller and less sepatate ascospores, Redingeria uniseptata from Brazil, which differs from R. vulcani in having smaller and 1-septate ascospores, Thalloloma intermedium from Brazil, which differs from T. anguiniforme in having smaller ascospores. Chapsa pulchella from Malaysia is a new record for Borneo and the first finding after its description, and Redonographa parvispora from Brasil is a new addition to the lichen biota of this country. All species mentioned are described and illustrated with close-up photographs.
