Fungal species identities are often based on morphological features, but current molecular phylogenetic and other approaches almost always lead to the discovery of multiple species in single morpho-species. According to the morphological species concept, the ant-parasitic fungus Rickia wasmannii (Ascomycota, Laboulbeniales) is a single species with pan-European distribution and a wide host range. Since its description, it has been reported from ten species of Myrmica (Hymenoptera, Formicidae), of which two belong to the rubra-group and the other eight to the phylogenetically distinct scabrinodis-group. We found evidence for R. wasmannii being a single phylogenetic species using sequence data from two loci. Apparently, the original morphological description (dating back to 1899) represents a single phylogenetic species. Furthermore, the biology and host-parasite interactions of R. wasmannii are not likely to be affected by genetic divergence among different populations of the fungus, implying comparability among studies conducted on members of different ant populations. We found no differences in total thallus number on workers between Myrmica species, but we did observe differences in the pattern of thallus distribution over the body. The locus of infection is the frontal side of the head in Myrmica rubra and M. sabuleti whereas in M. scabrinodis the locus of infection differs between worker ants from Hungary (gaster tergites) and the Netherlands (frontal head). Possible explanations for these observations are differences among host species and among populations of the same species in (i) how ant workers come into contact with the fungus, (ii) grooming efficacy, and (iii) cuticle surface characteristics.

L’identification des espèces fongiques est souvent basée sur des caractéristiques morphologiques, mais les approches phylogénétiques moléculaires et autres conduisent presque toujours à la découverte d’espèces multiples dans une seule morpho-espèce. Selon le concept d’espèce morphologique, le champignon parasite de fourmis Rickia wasmannii (Ascomycota, Laboulbeniales) est une espèce unique ayant une répartition paneuropéenne et une large gamme d’hôtes. Depuis sa description, il a été signalé chez dix espèces de Myrmica (Hymenoptera, Formicidae), dont deux appartiennent au groupe rubra et les huit autres au groupe scabrinodis, phylogénétiquement distinct. Nous avons trouvé que R. wasmannii était une seule espèce phylogénétique en utilisant les données des séquences de deux loci. Apparemment, la description morphologique originale (datant de 1899) représente une seule espèce phylogénétique. De plus, la biologie et les interactions hôte-parasite de R. wasmannii ne devraient pas être affectées par une divergence génétique entre différentes populations du champignon, ce qui implique une comparabilité entre les études conduites sur des membres de différentes populations de fourmis. Nous n’avons trouvé aucune différence dans le nombre total de thalles chez les ouvrières entre les espèces de Myrmica, mais nous avons observé des différences dans le schéma de distribution des thalles sur le corps. Le locus d’infection est le front de la tête chez Myrmica rubra et M. sabuleti, alors que chez M. scabrinodis, le lieu d’infection diffère entre les ouvrières de Hongrie (tergites abdominaux) et des Pays-Bas (front de la tête). Les explications possibles de ces observations sont les différences entre les espèces hôtes et entre les populations de la même espèce en ce qui concerne (i) le contact des ouvrières avec le champignon, (ii) l’efficacité du toilettage et (iii) les caractéristiques de la surface de la cuticule.

Department of Evolutionary Zoology and Human Biology University of Debrecen Egyetem tér 1 4032 Debrecen Hungary

Department of Molecular Biotechnology and Microbiology University of Debrecen Egyetem tér 1 4032 Debrecen Hungary

Faculty of Science University of South Bohemia Branišovská 31 37005 České Budějovice Czech Republic

Farlow Reference Library and Herbarium of Cryptogamic Botany Harvard University 22 Divinity Avenue Cambridge MA 02138 USA Faculty of Science University of South Bohemia Branišovská 31 37005 České Budějovice Czech Republic Department of Botany and Plant Pathology Purdue University 915 W State Street West Lafayette IN 47907 USA

Gemene Bos 12 1861 HG Bergen The Netherlands

Meise Botanic Garden Nieuwelaan 38 1860 Meise Belgium

Natural History Museum of Denmark University of Copenhagen Universitetsparken 15 2100 København Ø Denmark

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