The Cumacean (Crustacea: Peracarida) Genus Petalosarsia (Pseudocumatidae) from the Pacific Ocean

Tadashi Akiyama, Sarah Gerken

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


The distribution of the cumacean family Pseudocumatidae is restricted to the North Atlantic, Mediterranean and brackish waters of the Pont-Caspian region, except for three known species of the genus Petalosarsia. The present study describes nine species of Petalosarsia from Japanese waters, the Sulu Sea, the North-west Pacific, the Indo-West Pacific, and the Tasman Sea, Australia. The occurrence of P. declivis (Sars, 1865) in northern Hokkaido agrees with the reported circumpolar distribution of this species. Four species from the Pacific coast of southern Japan and the East China Sea, P. brevirostris Gamô 1986, P. ovalis sp. nov., P. ryukyuensis sp. nov. and P. gamoi sp. nov., are characterized by prominent dorsolateral carinae with teeth anteriorly and the basis of the 2nd maxilliped with a semicircular plate on the ventral surface. Nine specimens collected from the Sulu Sea included five species, P. brevirostris, P. gamoi, P. jonesi sp. nov. P. suluensis sp. nov. and P. longicauda sp. nov. The latter three species were characterized by no or faint dorsolateral carinae on the carapace. Among them, P. jonesi was similar to P. longirostris from the eastern tropical deep Atlantic. Petalosarsia australis sp. nov. from the Tasman Sea is characterized by one faint pair of dorsolateral carinae running for the entire length of the carapace. The species richness of Petalosarsia in the Sulu Sea and the Indo-West Pacific suggests a wide distribution of ancestors of Pseudocumatidae around the ancient Tethys Sea, with the Ponto-Caspian region located near the center. The habitat of Petalosarsia was mostly deeper than 200 m.

Original languageEnglish
Pages (from-to)1-35
Number of pages35
Issue number3320
Publication statusPublished - May 22 2012


  • Cumacea
  • Indo-West Pacific
  • Northwest Pacific
  • Petalosarsia
  • Pseudocumatidae

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Animal Science and Zoology


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