Red algal parasites are highly host-specific organisms that are morphologically reduced with decreased pigmentation. The initial morphological description of Asterocolax led to the creation of an independent genus devoted to these parasitic species, but molecular data have repeatedly demonstrated that Asterocolax species, and likely many other red algal parasites, resolve within the genera of free-living red algae, often within the same genus as their hosts. Here we conduct a long-overdue taxonomic revision of the red algal parasitic genus Asterocolax, describe a new species within the genus, and propose nomenclatural changes for four other species to reduce the polyphyletic clades encompassing Asterocolax.