Marionia elongoviridis is a species of sea slug, a dendronotid nudibranch, a marine gastropod mollusc in the family Tritoniidae.

[2] This species was described from Culebra Island in the Verde Island Passage, Philippines, 13°37′49″N 120°56′50″E / 13.63018°N 120.94725°E / 13.63018; 120.94725.

[1] It has been reported from Pulau Sangeang, 8°10′58″S 118°59′12″E / 8.18282°S 118.98663°E / -8.18282; 118.98663, Indonesia.

[3]