Laboulbeniales are highly specialized arthropod-associated fungi. The majority of the almost 2200 known species live on insects, although they also occur on other arthropod hosts. Recently, the number of Laboulbeniales associated with millipedes has increased considerably. Here we describe the first species of a Laboulbeniales fungus, Troglomyces twitteri sp. nov., from an American millipede. The new species was initially discovered on a photo of Cambala annulata (Say, 1821) from Ohio, USA, which had been shared on Twitter. A subsequent microscopic study of Cambala millipedes in museum collections in Denmark and France confirmed the discovery.