Tetradactylus fitzsimonsi, commonly known as Fitzsimons' long-tailed seps and FitzSimons' whip lizard, is a species of lizard in the family Gerrhosauridae. The species is endemic to South Africa.
The specific name, fitzsimonsi, is in honour of Irish-born South African herpetologist Frederick William FitzSimons.
The preferred natural habitats of T. fitzsimonsi are grassland and shrubland.
T. fitzsimonsi has no front legs. Its hind legs are minute, with only one toe on each foot. Adults may attain a snout-to-vent length (SVL) of about and a total length (including a long tail) of about .
T. fitzsimonsi is oviparous. A clutch of 2âÂÂ5 eggs is laid in a live ant nest (Anochetus faurei). Communal nesting has been observed. Each egg measures about . Each hatchling has a total length (including tail) of about .