In content such as Deep Dungeon and Eureka, mobs don't care what direction you attack from. To signal this to the player, the mobs' target circles are unornamented circles.

Please consider adding a front arrow to show the direction the target is facing. While the positional marker (the rear gap) is only useful when playing a positional job and fighting mobs that care about positionals, the direction a mob is facing is almost always important. Mobs often have conal or linear attacks that target the front or rear, these attacks are not always telegraphed, and the direction the mob is facing is not always clear just from looking at the enemy model itself.

Either the same arrow that is already used for normal mobs, or a modified arrow to differentiate the mob from normal mobs, would work.

In summary: