F. Ritter described this species in 1980 in volume 3 of his work “Kakteen in Südamerika”. He indicates the Cordillera de la Punilla in the province of Coquimbo, Chile as type location. It was Mr Rudolf Wagenknecht from La Serena who had found the plant at an altitude of about 2000 m.
South of San Felix, Chile we finally found Maihueniopsis wagenknechtii in 2017.
A look inside the flower shows the dark purple stigma.
At a little lower altitude we found this plant with a brighter flower and fruits.
Maihueniopsis wagenknechtii SAR 15901 near La Plata, Chile.