In: Sydowia 75, (2022): 053-074; ISSN 0082-0598, DOI 10.12905/0380.sydowia75-2022-053, Published online on November 29, 2022

Hesperomyces harmoniae, a new name for a common
ectoparasitic
fungus on the invasive alien ladybird
Harmonia axyridis

Danny Haelewaters, Warre Van Caenegem & André De Kesel

Research Group Mycology, Department of Biology, Ghent University, Ghent, Belgium
Biology Centre, Czech Academy of Sciences, C?eské Bude?jovice, Czech Republic
Faculty of Science, University of South Bohemia, C?eské Bude?jovice, Czech Republic
Meise Botanic Garden, Meise, Belgium

* e-mail: danny.haelewaters@gmail.com

Haelewaters D., Van Caenegem W. & De Kesel A. (2022): Hesperomyces harmoniae, a new name for a common ectoparasitic
fungus on the invasive alien ladybird Harmonia axyridis. – Sydowia 75: 53–74.
Fungi in the order Laboulbeniales (Ascomycota, Laboulbeniomycetes) are obligate, microscopic ectoparasites of arthropods.
These fungi, unlike their close relatives, never form hyphae. Instead, they produce a three-dimensional thallus that consists of
several hundred to a thousand vegetative cells derived from a two-celled ascospore by determinate mitotic divisions. Of 2,325
described species, 80 % are known from beetles (Coleoptera). Hesperomyces is a genus of 11 species associated with ladybirds
(Coleoptera, Coccinellidae) and false skin beetles (Biphyllidae). One species, Hesperomyces virescens, is known from all continents
except Australia and Antarctica, and has been reported on 30 ladybird hosts in 20 genera. Previous work, based on geometric
morphometrics, molecular phylogeny, sequence-based species delimitation methods, and host information, pointed out that
He. virescens is a complex of multiple species segregated by host. Here, we formally describe the most recorded species in the
complex, Hesperomyces harmoniae—parasite of the harlequin ladybird Harmonia axyridis, a globally invasive species. Using
DNA isolates of Hesperomyces from multiple host species, including the host on which He. virescens was originally described
(Chilocorus stigma), we found that He. harmoniae forms a single clade in our phylogenetic reconstruction of a two-locus ribosomal
dataset. Hesperomyces harmoniae is currently known from five continents and 31 countries: Canada, El Salvador, Mexico,
the USA (North America); Argentina, Colombia, Ecuador (South America); Austria, Belgium, Bulgaria, Croatia, Czech Republic,
France, Germany, Greece, Hungary, Italy, Luxembourg, Montenegro, The Netherlands, Poland, Romania, Russia, Serbia, Slovakia,
Switzerland, the UK (Europe); South Africa (Africa); China, Japan, and Turkey (Asia).

Keywords: arthropod-associated fungi, Coccinellidae, integrative taxonomy, phylogeny, ribosomal DNA, species delimitation.
– 1 new species.