• homeHome
  • School of Applied Biological Science
  • "Taxonomic reassessment of a calcifying red alga common to the Pacific Ocean with the discovery of a new species based on specimens collected by a Japanese researcher over 100 years ago" reported by Aki KATO

"Taxonomic reassessment of a calcifying red alga common to the Pacific Ocean with the discovery of a new species based on specimens collected by a Japanese researcher over 100 years ago" reported by Aki KATO

Key points of this research

  • Coralline algae are a calcifying red algal group that firmly deposit calcium carbonate on cell walls and play various important roles in marine ecosystems, such as reef-building organisms and morphogenic inducers of marine invertebrates.
  • A coralline red alga Lithophyllum okamurae is one of the most common species along the coasts of Japan, which was described based on specimens collected in Japan by a Japanese researcher more than 100 years ago.
  • In this study, we revealed the genuine L. okamurae among the species referable to this species from the Indian Ocean to the Pacific Ocean and further discovered a new species Lithophyllum neo-okamurae.

Content of research

  • Taxonomy of species referable to “Lithophyllum okamurae

The coralline alga Lithophyllum okamurae has a pink body with many short warts and is easily found in the lower intertidal zone and tide pools. Accordingly, this species has often appeared in field guides of coastal marine organisms and seaweeds for the general public.
This species was described by the Norwegian phycologist Mikael Foslie as Lithophyllum okamurae (Japanese name: Hira-ibo), based on specimens collected by the Japanese phycologist Kichisaburo Endo in Miura City, Kanagawa Prefecture (type locality) in 1899. In the following few years, Foslie described two forms of this species based on specimens from the type locality; however, it remained unclear which form was the genuine L. okamurae.

Therefore, we conducted research using genetic and morphological data of Endo's specimens, including the type specimens of these two forms, which are housed in the herbarium of the Norwegian University of Science and Technology, and newly collected specimens from the coasts of Japan. Both forms were genuine L. okamurae. Furthermore, the specimens collected by Endo contained a new species different from this species, so we named it "Lithophyllum neo-okamurae". L. okamurae and the new species were sympatrically distributed along the coasts of Japan. In addition, the existence of genetically conspecific entities with L. okamurae was confirmed in Taiwan and the Gulf of California.

Lithophyllum okamurae
(Left) Specimen with incisor-shaped protuberances
(Yamada, Teradomari, Niigata Prefecture, Japan. Collection date: November 13, 2008);
(right) specimens with round protuberances
(Shiki-misaki, Reihoku, Kumamoto Prefecture, Japan. Collection date: March 10, 2012) 

New species Lithophyllum neo-okamurae
Specimens with round protuberances
(Yokoshima Island, Uwajima, Ehime Prefecture, Japan. Collection date: July 30, 2014) 

  • Prospects

Recent studies have revealed that coralline algae are vulnerable to ocean acidification and global warming, and have been concerned that these environmental changes may negatively impact various organisms that coexist with coralline algae. On the other hand, it has recently been understood that definitions and distributional ranges of several dominant species based on morphological identification are often not accurately recognized. Accordingly, to ensure reproducible research on the responses of coralline algae to environmental stress, it is essential to apply reliable species names and understand the exact distributional range of each species.

Information details of publication

  • Journal: Phycologia
  • Title: Morphological and molecular assessment of Lithophyllum okamurae with the description of L. neo-okamurae sp. nov. (Corallinales, Rhodophyta) 
  • Authors: Aki Kato, Daniela Basso, Annalisa Caragnano, Graziella Rodondi, Line Le Gall, Viviana Peña, Jason M. Hall-Spencer & Masasuke Baba
  • DOI: 10.1080/00318884.2021.2005330 

Associate Professor Aki KATO
Takehara Fisheries Research Station
School of Applied Biological Science
Tel:0846-24-6781   FAX: 0846-23-0038
E-mail:katoa*hiroshima-u.ac.jp (Note: Please replace *with @)