Ants of the genus Myrmica are so far only known to host Laboulbeniales of the genus Rickia. During a pitfall trapping campaign in a wet meadow at Meise Botanic Garden (Belgium), an infected population of Clivina fossor (Coleoptera, Carabidae) was sampled. Clivina fossor is the main host of Laboulbenia clivinalis (Laboulbeniales). The traps also contained huge numbers of Myrmica scabrinodis (Hymenoptera, Formicidae). Screening of these ants was negative for Rickia wasmannii, but revealed 2 specimens carrying mature thalli of L. clivinalis. Thalli were normally developed and perithecia contained fully developed spores. We here report a first case of host shifting of a carabidicolous Laboulbenia towards an ant host. Although extremely rare, these finds support the hypothesis of ‘habitat specificity’, i.e., that species of Laboulbeniales can shift between variously related hosts sharing the same micro-habitat. Myrmica scabrinodis is here considered an accidental host for L. clivinalis.