Hormophysa cuneiformis, a brown macroalga in the family Sargassaceae, is now documented from Pohnpei based on a specimen collected in May 1957 and recently discovered in the Herbarium Pacificum of the Bishop Museum. Previously documented collections of H. cuneiformis in Micronesia were made from Palau in the western Pacific in July 1968 and January 1971, and Pagan Island in the Northern Mariana Islands in July 1975.

Partial sequences of the large subunit (LSU) and small subunit (SSU) of the ribosomal DNA of fucalean algae (Phaeophyceae) from the northern and the southern hemispheres, as well as from other brown algal genera such as Durvillaea, were analysed and compared with available morphological data. Combined SSU+LSU sequence data appear to be suitable for inferring phylogenetic relationships within the Fucales. Results suggest that Durvillaea and Notheia should be included in the Fucales and that the paraphyletic Cystoseiraceae be merged into a large family, Sargassaceae Kützing emend. De Toni. The genus Axillariella, the taxonomic position of which was uncertain, clearly belongs to the Sargassaceae. At present, at least seven families are recognized in the order Fucales: Durvillaeaceae, Seirococcaceae, Notheiaceae, Sargassaceae, Himanthaliaceae, Hormosiraceae and Fucaceae. More investigations are needed to assess whether Xiphophora should be placed in its own family.