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Three species are recognized, D. pulchra Hoeg 1930 (from the Bloukrans River in the Knysna district, Ceres Subgroup, Lower Bokkeveld Group), D. alfreda Plumstead 1967 (Port Alfred, Weltevrede Subgroup, Lower Witteberg Group) and D. maraisia Plumstead 1967 (Howisons Poort, Witpoort Sandstone, Middle Witteberg Group).
The Bloukrans River below forms the border between the Eastern Cape and Western Cape provinces and is located in the Tsitsikamma region of the Garden Route.