Planet Four: Terrains – Discovery of araneiforms outside of the South Polar layered deposits

•We present the first results from the Planet Four: Terrains online citizen science project.•Over 10,000 volunteers participated in the visual inspection of CTX (Context Camera) images.•Volunteers identified araneiforms, erosional features characteristic of the South Polar Residual Cap, and craters.•We present the distributions of the classic spider araneiforms and Swiss cheese terrain identifications in 90 CTX images.•High resolution imaging confirms the discovery of araneiforms at locations outside of the South Polar Layered Deposits.