XVI International Botanical Congess

We describe a new red alga parasitic on Pterocladiella bartlettii from Venezuela. It produces erumpent masses of cortical and medullary host cells surrounding the parasitic filaments, which penetrate deeply into the host tissue. The zonate tetrasporangia and catenated spermatangia, borned in conceptacles, circunscribe this species to the genus Pterocladiophila Fan & Papenfuss, but the wart-like morphology, shape and size of the tetrasporangial conceptacles, and carpogonial features shows that it is an undescribed species. Aditionally, post-fertilization events shows that the ordinal position of Pterocladiophila and Pterocladiophilaceae into the Gracilariales, may be incorrect. We suspect that further studies will show that this parasitic algae could be assigned to a new red algal order.