Description of four new species of marine macroalgae from Rangitāhua, New Zealand

Four species of marine macroalgae are described from Rangitāhua, the northern islands of the New Zealand archipelago. The flora of this region has been considered to have its strongest affinities with other warm‐water regions of the Pacific and Indian Oceans, with very low levels of endemism. Many of the taxa from the region have been known from three or fewer collections, and previously many were only identified to genus as key morphological, and anatomical features required for species‐level identifications were not available, and there were few species for which sequence data were available. Three of the new species, belonging to the genera Codium, Delisea , and Pyropia , were previously reported from Rangitāhua under other names. Sequence data have revealed them to differ from species from mainland New Zealand and the wider Pacific, and they are currently considered to be endemic to the region. The discovery of a new species of the New Zealand endemic genus Psilophycus, also confirmed by sequence data, is of particular interest given the genus has been regarded as monotypic and endemic to the northern North Island of New Zealand. This research provides new insights into the relationships of the flora, with additional newly discovered taxa revealed through sequencing data awaiting description.