Gracilaria vermiculophylla: A western Pacific species of Gracilariaceae (Rhodophyta) first recorded from the eastern Pacific

SUMMARY We report Gracilaria vermiculophylla (Ohmi) Papenfuss from the Pacific coast of North America based on a morphoanatomical revision and comparison of sequences of the nuclear gene coding for the small subunit of ribosomal RNA and the internal transcribed spacers of populations from Baja California, Mexico and Hiroshima, Japan. It is the first convincing report of this species out of its center of distribution in western north Pacific, where it has been considered as a synonym of former ‘G. verrucosa’ records. G. vermiculophylla also occurs in central California as indicated by internal transcribed spacer sequences of a previously unknown Gracilaria Greville material. In the northeastern Pacific G. vermiculophylla is characterized by a robust somewhat vermiform, well‐branched cylindrical thallus, with gradual cell size transition from cortex to medulla, deep spermatangial conceptacles, regular chains of carposporangia and carposporangial initials, downwardly oriented tubular nutritive cells, but rarely with upwardly oriented tubular nutritive cells. In some features of its cystocarp anatomy G. vermiculophylla is related to Gracilariopsis E. Y. Dawson or Hydropuntia Montagne and it is a relevant species for discussions about Gracilariaceae genera.