Basilissopsis rhyssa is a species of sea snail, a marine gastropod mollusc in the family Seguenziidae.
The height of the shell attains 2.1 mm. The shell is very similar to the shell of Basilissopsis watsoni <small>Dautzenberg & H. Fischer, 1897</small>. The shell is nacreous and the outer lip possesses posterior and basal labral sinuses.
This marine species occurs in the Gulf of Mexico, in the Caribbean Sea off Cuba and in the Atlantic Ocean off Georgia.