Cantuaria marplesi is a species of trapdoor spider endemic to New Zealand.
This species was described in 1945 by Valerie Todd Davies from a female specimen in Duntroon. The species was transferred to the Cantuaria genus by Ray Forster in 1969. The holotype is stored at Otago Museum.
The female is recorded at 15mm in length. The carapace and legs are orange brown. The abdomen is grey on the dorsal surface.
This species is only known from Otago in New Zealand.
Under the New Zealand Threat Classification System, this species is listed as Data Deficient with the qualifiers of "Data Poor: Size" and "Data Poor: Trend".