Mioawateria extensa is a species of sea snail, a marine gastropod mollusk in the family Raphitomidae.

The shell is in most features like Pleurotomella normalis (Dall, 1881), but more elongated, with nine whorls, the revolving threads (except the sutural ones) obsolete except near the anterior end of the body whorl.

With a tendency of the thread next the suture to be stronger and more strongly knobbed than (as in the normal form) the outer one.

There are twenty to twenty-five transverse threads, more numerous and in large specimens hardly noticeable except near the suture.

[2] M. extensa can be found in Caribbean waters, ranging from the coast of Louisiana to Cuba.