Delta(8)-fatty-acid desaturase which introduces a double bond at the 8-position in the long-chain base (LCB) of ceramides. Required for the formation of the di-unsaturated sphingoid base (E,E)-sphinga-4,8-dienine during glucosylceramide (GluCer) biosynthesis. an N-acylsphing-4-enine + 2 Fe(II)-[cytochrome b5] + 2 H(+) + O2 = a (4E,8E)-4-sphinga-4,8-dienine ceramide + 2 Fe(III)-[cytochrome b5] + 2 H2O Lipid metabolism; sphingolipid metabolism. Has a decreased hyphal growth rate and is highly sensitive to SDS and fluconazole. Belongs to the fatty acid desaturase type 1 family.