Puccinia galiiuniversa, a new caricicolous rust fungus systemically inhabiting Galium aparine in its spermogonial–aecial stage

•A new caricicolous rust fungus, Puccinia galiiuniversa, was described.•The rust systemically inhabits host plants of Galium in its spermogonial–aecial stage.•The plants of Galium systemically infected by the rust turned out to be sterile.

Field observations and inoculation experiments revealed that spermogonia and aecia produced on systemically infected plants of Galium aparine and uredinia and telia on Carex maackii are different stages of the life cycle of a Puccinia fungus. By comparative morphology with allied species, the fungus was concluded to be a new species and named as Puccinia galiiuniversa.