title: Three new dicyemids from Octopus sasakii (Mollusca: Cephalopoda: Octopoda).
abstract: Three new species of dicyemid mesozoan are described from Octopus sasakii Taki, 1942, collected from Tosa Bay and Kii Strait in Japan. Dicyema shimantoense n. sp. is a medium-size species that reaches about 3,000 microm in length, and lives in folds of the renal appendages. The vermiform stages are characterized by having 22 peripheral cells, a conical 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 codonocephalum n. sp. is also a medium-size species that reaches about 2,000 microm in length. It too lives in folds of the renal appendages. The vermiform stages are characterized by having 17-22 peripheral cells, an elongated calotte, and an axial cell that extends to the middle of propolar cells. Infusoriform embryos consist of 37 cells; a single nucleus is present in each urn cell, and the refringent bodies are solid. Dicyemennea pileum n. sp. is a medium species that reaches about 2,000 microm in length. It attaches to the surface of the renal appendages. The vermiform stages are characterized by having 23 peripheral cells, a disc-shaped calotte, and an axial cell that extends to the propolar cells. An anterior abortive axial cell is absent in vermiform embryos. Infusoriform embryos consist of 38 cells; 2 nuclei are present in each urn cell, and the refringent bodies are liquid. These are the first dicyemids to be described from Octopus sasakii.
authors.affiliation: Department of Biology, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan. hfuruya@bio.sci.osaka-u.ac.jp
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Furuya
mesh_terms: D000818:Animals; D005260:Female; D007448:Invertebrates / Q000033:anatomy & histology / Q000145:classification*; D007564:Japan; D008297:Male; D049831:Octopodiformes / Q000469:parasitology*