Pinguiochrysis pyriformis gen. et sp. nov. (Pinguiophyceae), a new picoplanktonic alga isolated from the Pacific Ocean

Authors

  • Masanobu Kawachi,

    Corresponding author
    1. Marine Biotechnology Institute Co. Ltd, Kamaishi Laboratory, Kamaishi 026-0001, Japan
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    • National Institute for Environmental Studies, Tsukuba 305–8506, Japan.

  • Mika Atsumi,

    1. Marine Biotechnology Institute Co. Ltd, Kamaishi Laboratory, Kamaishi 026-0001, Japan
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  • Hisato Ikemoto,

    1. Marine Biotechnology Institute Co. Ltd, Kamaishi Laboratory, Kamaishi 026-0001, Japan
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    • Suntory Limited, Technological, Development Center, Yamazaki, Shimamoto-Cho, Mishima-Gun, Osaka 618–0001, Japan.

  • Shigetoh Miyachi

    1. Marine Biotechnology Institute Co. Ltd, Kamaishi Laboratory, Kamaishi 026-0001, Japan
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  • Communicating editor: T. Motomura.

* To whom correspondence should be addressed. Email: kawachi@nies.go.jp.

SUMMARY

Pinguiochrysis pyriformis gen. et sp. nov. is a brown, naked, non-motile, marine picoplankton. A culture was established from a surface sample collected in 1991 from the tropical Western Pacific Ocean. Typical cells of P. pyriformis are distinctively pear-shaped and have one ovoid chloroplast; these two features distinguish this species from the other picophytoplankton species. However, the pyriform morphology is not consistent and cells frequently change to a subspherical shape. The chloroplast and mitochondrion ultrastructure confirm that this species belongs to the photosynthetic stramenopiles (chromophytes). Additional distinctive ultrastructural characteristics of P. pyriformis include (i) a chloroplast envelope forming a tubular invagination that penetrates into the pyrenoid; (ii) thylakoid lamellae consisting of more than three layers in some cells; (iii) the lack of basal bodies and centrioles; and (iv) the lack of scales or other extracellular structures. Based on the morphological features, this picoplanktonic species was described as a new species and placed in the Pinguiophyceae on the basis of the molecular phylogenetic analysis and biochemical data published elsewhere.

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