Hypselodoris saintvincentius is a species of sea slug or dorid nudibranch, a marine gastropod mollusk in the family Chromodorididae.

[1] This species was described from the intertidal zone at Coobowie, west coast of St Vincent Gulf, South Australia 35°02′39″S 137°44′24″E / 35.044260°S 137.739888°E / -35.044260; 137.739888.

[2] Hypselodoris saintvincentius has a dark blue-black body which is covered in hundreds of small black and white spots.

There is typically a creamy-white irregular, lined pattern present on its dorsum.

This species can reach a total length of at least 40 mm and has been observed feeding on sponges from the genus Dysidea.