Roussoëlla is a genus of fungi in the family Roussoellaceae. The genus is characterized by two-celled ascospores, unitunicate asci with a small spherical apical ring that stains slightly blue with Melzer's reagent, and stromata with several perithecia. The genus was circumscribed by Italian mycologist Pier Andrea Saccardo in 1888, with Roussoella nitidula assigned as the type species. The generic name honours Marietta Hannon Rousseau, (1850âÂÂ1926), who was a Belgian mycologist and taxonomist.
Roussoellaceae was introduced by Liu et al. (2014) and contains three genera; Neoroussoella, Roussoella and Roussoellopsis.