Diagnoses and descriptions of the adults and pupal exuviae of Stygocladius multisetosus gen. nov., sp. nov., are provided based primarily on male and female pharates collected in temporary basaltic and karstic helocrenes in southern France and Algeria. Features on the adult male, female and pupa indicates that it belongs to the Heterotrissocladius group of genera and is probably most closely related to Paratrissocladius Zav el. The immature stages of the new species are stygobiontic. doi: 10.5324/fn.v31i0.1363. Published online: 17 October 2012.