Aphantaulax trifasciata can reach a length of in females, of in males. The body is oblong-oval shaped, narrow and pointed at the back. The body color is black, with a broad transverse band of white hairs on the fore margin of abdomen, a second interrupted transverse band in the middle of the abdomen and a longitudinal white stripe on the cephalothorax. On the extremity of the abdomen sometimes there are two white spots. Legs are yellow-brown.