Leptotrophon spinacutus, also known as Poirieria spinacatus, is a species of sea snail, a marine gastropod mollusk in the family Muricidae, the murex snails or rock snails.
The length of the shell attains 9.5 mm.
Leptotrophon spinacutus was first described as such in a journal of the French National Museum of Natural History (1986) along with six other new species of Muricidae, by the Belgian malacologist .
This particular species was found south of the French territory of New Caledonia, 390-400m below sea-level. Houart describes it as having a medium-sized shell for its genus, and being white in color with pale brown blotches. It is covered by a thin white outer layer, the intritacalx (= the chalky outer layer).