In: Sydowia 79, (2026): 27-42; ISSN 0082-0598, DOI 10.12905/0380.sydowia79-2027-0027, Published online on may 5th, 2026

Island Icebreaker: first records of Laboulbeniales from Iceland

Felix Heyman, Renars Guts, Warre Van Caenegem, Vladimir I. Gusarov & Danny Haelewaters

Research Group Mycology, Ghent University, 9000 Ghent, Belgium
Department of Zoology, Faculty of Science, University of South Bohemia, 370 05 Ceské Budejovice, Czechia
Biology Centre of the Czech Academy of Sciences, Institute of Entomology, 370 05 Ceské Budejovice, Czechia
Natural History Museum, University of Oslo, NO-0318 Oslo, Norway

* e-mail: felixheyman2002@gmail.com

Heyman F., Guts R., Van Caenegem W., Gusarov V.I. & Haelewaters D. (2026) Island Icebreaker: First records of Laboulbeniales from Iceland. Sydowia 79: 27–42.

Laboulbeniales (Ascomycota, Pezizomycotina) are a notoriously understudied order of fungi found all over the world, and their presence in Iceland is only now being documented. These microfungi live as ectobiont commensals and ectoparasites on arthropods. In this study, arthropod specimens were collected on the Reykjanes Peninsula, which resulted in two new records of Laboulbeniales. The first record, Laboulbenia notiophili was observed on the host Notiophilus biguttatus (Coleoptera: Carabidae).
A morphological and molecular phylogenetic study confirmed that Laboulbenia notiophili shows no morphological or genetical differentiation compared to previous European records on the same host. Our molecular phylogenetic reconstruction supports the hypothesis that L. notiophili represents a complex of multiple species differentiated by their host association. The phylogenetic reconstruction based on ITS sequences revealed five clades: one associated with the Lebiini tribe, the second one with Notiophilus rufipes, the third one with remaining Notiophilus host species and the final two consisting of L. metableti and L. stilicicola. The second record, Rickia zanettii, was found on the host Omalium excavatum (Coleoptera: Staphylinidae) of which the first genetic data were generated. The length of R. zanettii was smaller compared to previous records of R. zanettii, but otherwise the morphology is identical. Additionally, the first Norwegian records of Rickia huggertii on Omalium cf. riparium were included in the phylogenetic analysis. These Icelandic records represent the first-ever observations of Laboulbeniales from the island, revealing gaps in the knowledge of the island’s fungal diversity. They also highlight the value of continued sampling, even in well-studied regions, and demonstrate that Wallacean shortfalls are not confined to understudied areas.

Keywords: Ascomycota, Laboulbenia notiophili, Laboulbeniomycetes, Rickia zanettii, species complex, Wallacean shortfall.