The polyclad Pseudoceros bicolor derives its name from a distinctive two-coloured dorsal colouration, which consists of a very dark, almost black central area with acute black lobes extending towards a translucent greyish margin. At least three different colour morphs have been described, ranging from a pale speckled brown through an evenly dark brown form, to a morphotype resembling the original species description. Pseudoceros aureolineatus is easily confused with the light brown colour morph of P. bicolor, and P. rawlinsonae resembles both P. bicolor and P. aureolineatus. Using morphological characters of newly collected specimens and nucleotide sequences of the 28S ribosomal DNA gene, the taxonomic validity of P. rawlinsonae and P. bicolor is confirmed and the descriptions of their colouration are emended. The new subspecies, P. bicolor marcusorum subsp. nov. is erected, the genus Cryptoceros is eliminated, and the new combination Maritigrella aureolineata comb. nov. (Euryleptidae) is established for P. aureolineatus.