A new red algal crust from New Zealand: <i>Apophlaea darchinoae</i> sp. nov. (Hildenbrandiales)

New Zealand’s algal flora is still far from fully explored, and new taxa continue to be discovered. The taxonomy of the red algal order Hildenbrandiales, consisting mostly of crustose members, is controversial as descriptions are largely based on limited morphological features. The order Hildenbrandiales is also in a close, apparently obligate, relationship with an endophytic fungus. <i>Apophlaea</i> is a genus in this order currently comprising two described species, both endemic to New Zealand. The morphology of this genus is more complex than that of other members of the Hildenbrandiales as it consists of extensive upright thalli. Sampling of <i>Apophlaea</i> in New Zealand, especially in the southern part of the North Island, has led to the discovery of a genetically distinct entity, that is only crustose. We propose a new species for this entity, <i>Apophlaea darchinoae</i> sp. nov., which is found on rocks in the high intertidal zone. This species has the typical tetrasporangial conceptacles of <i>Apophlaea</i> and no other reproductive structures were observed, and it consists of filaments that are laterally joined by secondary pit connections. <i>Apophlaea darchinoae</i> can be found in sympatry with <i>A. sinclairii</i> in the north of the North Island. We provide molecular evidence for the distinct nature of <i>A. darchinoae</i> and provide observations of extensive fungal filaments within this new species.