Toxiclionella tumida is a species of sea snail, a marine gastropod mollusk in the family Clavatulidae.

The ground color of the shell is light green, with a reddish tone between the arcuate, opisthocline ribs and with a thick, olive-brown periostracum.

The acuminate, orthoconic spire ends abruptly in a large blunt protoconch.

The outer lip shows a thick callus and parietal tubercle.

[3][4] This marine species occurs along the Agulhas Bank, South Africa.