Porphyroglossum is the last one of nine genera within the family Gelidiaceae that has yet to be analyzed by molecular markers. We analyzed rbcL and cox1 genes from P. zollingeri specimens collected near the type locality in Indonesia and compared them with other gelidioid algae. Thalli are cartilaginous, complanate, and up to 15 cm high. Abundant rhizoidal filaments are concentrated in the medullary layer. Tetrasporangial sori are on small, determinate ramuli. In all gene analyses, P. zollingeri consistently nested within Gelidium. The sister relationship of P. zollingeri to G. floridanum was well resolved. Because Gelidium has priority over Porphyroglossum, a new combination is proposed, viz. Gelidium zollingeri. Network analysis of the four cox1 haplotypes revealed many missing haplotypes, indicating high genetic diversity in the species.