The brownmargin flathead was first formally described in 1996 by Leslie W. Knapp with its type locality given as the Arafura Sea.

[1] This taxon was previously regarded as a population of the crocodile flathead (C. crocodilus) but were recognised as a valid species in 1996.

The supraorbital ridge is typically smooth at the front and has between seven and ten 7-10 small spines on its rear.

The overall colour is brownish to reddish-brown marked with a dense brown speckling on the rear of the body becoming sparse towards the head.

[5] The brownmargin flathead is endemic to the northern continental shelf of Australia where it has been recorded only from the Arafura and Timor Seas.