Planarian secretory cell nidovirus (PSCNV) is a virus of the species Planidovirus 1, a nidovirus notable for its extremely large genome. At 41.1 kilobases, it is the largest known genome of an RNA virus. It was discovered by inspecting the transcriptomes of the planarian flatworm Schmidtea mediterranea and is the first known RNA virus infecting planarians. It was first described in 2018.