Abstract
Pyropia raulaguilarii sp. nov. is described from Michoacán, tropical Mexican Pacific, on basis of comparative morphology and nrSSU, rbcL sequence analysis. It is distinguished from other Pyropia species by the foliose and lanceolate gametophyte, a monoecious thallus and the zygotosporangia in packets of 2x2x4. The phylogenetic analysis showed that the two Pacific Mexican samples, from Caletilla and Carrizalillo (Michoacán), were almost identical and formed a distinctive and well supported clade segregated from other species of Pyropia from Brazil, USA and Mexico. The Mexican entity is morphologically and genetically distinct from other Pyropia species, suggesting that this species should be assigned to a new taxon.