We describe Algaria nataliei, a new genus and species from the Worcester-Robertson Karoo region, Western Cape Province, South Africa. Particularly distinctive features of the new genus are the strongly dimorphic leaves with the upper toothed to laciniate-margined, apically notched on one side, and long-awned and the lower entire, weakly but distinctly cucullate and with the costa ending in the apex, the laminal cells bulging ventrally and smooth to weakly papillose but flattened dorsally and strongly papillose, the immersed macrostomous eperistomate capsules with flat to umbonate opercula and flattened or indented bases, and long-conic to mitrate, prorate-papillose calyptrae. [ABSTRACT FROM AUTHOR]