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

1 Research Group Mycology, Department of Biology, Ghent University, Ghent, Belgium
2 Biology Centre, Czech Academy of Sciences, C?eské Bude?jovice, Czech Republic
3 Faculty of Science, University of South Bohemia, C?eské Bude?jovice, Czech Republic
4 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.