The Crustose Brown Algae of New Zealand: a Taxonomic Study

Nine species of crustose brown algae are described from New Zealand’s coast. Three species are microthalli of species of Scytosiphonaceae: Colpomenia bullosa Yamada, Scytosiphon lomentaria (Lyngbye) Link and Petalonia binghamiae (J. Agardh) Vinogradova. One species of Lithodermataceae, Pseudolithoderma roscoffense Loiseaux is described from Northland. Four species are Ralfsiaceae, Ralfsia expansa (J. Agardh) J. Agardh, Ralfsia confusa Hollenberg, a new species, Ralfisa sp. “smooth”, and Hapalospongidion gelatinosum Saunders. H. saxigenum Lindauer is identical to Hapalospongidion gelatinosum Saunders. One new species of Diplura, currently placed in the Ralfsiaceae, is described. Ralfsia verrucosa (Areschoug) Areschoug, previously reported from New Zealand, was not found. ITS-2 sequences show that Ralfsia expansa, Ralfsia confusa and Ralfsia sp. “smooth” are closely related. Ralfsia expansa is more distantly related. These relationships are consistent with morphological differences. LSU nrDNA sequences show Diplura sp. and Pseudolithoderma roscoffense are not closely related to other Ralfsiaceae. These algae form a weakly supported group with members of the Sphacelariales. Hapalospongidion and three Ralfsia species form a well supported group, but this group’s relationship to other phaeophycean orders is not resolved. These results are discussed in relation to plastid number and the status of the order Ralfsiales.