Ptychobela vexillum is a species of sea snail, a marine gastropod mollusk in the family Pseudomelatomidae, the turrids and allies.

Kilburn proposed in 1989 Brachytoma vexillum Habe & Kosuge, 1966 as a synonym of Ptychobela suturalis (Gray, 1838)[2] The epithet vexillium was probably a misspelling in the original text, but was not indicated as such.

Therefore, it takes priority over vexillum, published five-month later and repeated later by some authors.

This marine species occurs in the South China Sea, off the Philippines and Japan; also off Australia (Northern Territory, Queensland, Western Australia).

This Pseudomelatomidae-related article is a stub.