Platydoris macfarlandi is a species of sea slug, a dorid nudibranch, shell-less marine opisthobranch gastropod mollusks in the family Discodorididae.
This species was described from three specimens captured at depths of 157–161 m (515–528 ft). off Pismo Beach, San Luis Obispo Bay, California, 35°08′42″N 120°39′24″W / 35.144950°N 120.656636°W / 35.144950; -120.656636. It has also been found in deep water (55–113 m (180–371 ft)) at Redondo Canyon, Los Angeles County and at 30 m (98 ft) depth at Bahia San Cristobal, Baja California, Mexico, 27°24′28″N 114°39′40″W / 27.40778°N 114.66111°W / 27.40778; -114.66111.
