Three New Species of Dicyema (Dicyemida: Dicyemidae) from Octopus kagoshimensis (Mollusca: Cephalopoda: Octopodidae)

抄録

Three new species of dicyemid mesozoan are described from Octopus kagoshimensis Ortmann, 1888 collected off Irino in Tosa Bay, sourthern Shikoku, Japan. Dicyema tosaense sp. nov. is a small species that reaches about 800μm in length. The vermiform stages are characterized by 16-18 peripheral cells, a conical calotte, and an axial cell that extends to the base of the metapolar cells. Infusoriform embryos consist of 37 cells; two nuclei are present in each urn cell and the refringent bodies are solid. Dicyema irinoense sp. nov. is a species of medium size that reaches about 1300μm in length. The vermiform stages are characterized by 22 peripheral cells, a discshaped calotte, and an axial cell that extends to the base of the propolar cells. Infusoriform embryos consist of 37 cells; a single nucleus is present in each urn cell and the refringent bodies are solid. Dicyema sphaerocephalum sp. nov. is a species of medium size and reaches about 1000μm in length. The vermiform stages are characterized by 18-20 peripheral cells, a rounded calotte, and an axial cell that extends to the base of the propolar cells. Infusoriform embryos consist of 37 cells; two nuclei are present in each urn cell and the refringent bodies are solid. This is the first report of dicyemids in the octopus O. kagoshimensis.