Roseaplagis caelatus is a species of small sea snail in the family Trochidae, the top shells.
It is smaller than Cantharidus sanguineus (height: 5.5 mm, diameter 4.5 mm) but it is more deeply ribbed and its grooves are wider.The imperforate shell is more deeply ribbed, and the ribs narrower. They number 5 to 7 on the penultimate whorl, 15 to 16 on the body whorl. Sometimes they are obsoletely granose through being crossed by growth lines. The columella shows a slight swelling in the middle.
This marine species is endemic to New Zealand and occurs off the Foveaux Straits; Port Pegasus, Stewart Island; Snares and Bounty Islands
