There does not seem to be any definitve answer to this question, but if you have one, I would like to hear it
I have seen the very fast Cataglyphis piliscapus, but he Sahara Desert ant (cataglyphis bicolor) should be abel to run up to 1 meter pr. secound according to this (Hyperlinks sind nur für registrierte Nutzer sichtbar see note 22). That must be near the record.