It looks like a smaller Wandering Vagrant. They tend show up as elites, due to the level they appear on. They have as much health as a small boss, and hit as hard a stone golem in most cases. Despite being a Wandering Vagrant sub-type, they do not have a top-screen health bar and are not guaranteed to drop items, but will give off large amounts of money and experience.
They should be treated with some caution, but since you'll be at the U.E.S. Contact Light, you'll have bigger problems to worry about. Many may spawn at once, but continued movement will typically guarantee you never get hit. They have been confirmed to spawn with electric/fire/etc. modifiers, although it is hard to tell until they fire Nematocysts.
Besides, their Monster Log only unlock the Wandering Vagrant's information, so their hig spawn rate in the U.E.S. Contact Light can be useful to obtain Wandering Vagrant's Monster Log faster.