title: Fibrophrys columna gen. nov., sp. nov: A member of the family Amphifilidae.
abstract: A novel Diplophrys-like organism, Fibrophrys columna, was isolated from Hiuchigaike Pond in Japan. F. columna showed a nearly orbicular or broadly elliptical cell shape and has fine filamentous, branching ectoplasmic elements emanating from both polar ends of the cell. Cells also contain orange, amber, or colorless lipid bodies. Although its whole cell morphology resembles that of the genus Diplophrys, Fibrophrys is clearly distinct from Diplophrys on the basis of 18S rDNA sequences. Molecular phylogenetic analysis showed a close relationship of F. columna with Amphifila marina, and its sequence is similar to many environmental stramenopile sequences. The cells of F. columna measured 5.0-8.3×5.6-10.3μm and sometimes possessed hernia-like prongs instead of filamentous ectoplasmic elements. An axis-like electron-dense body was observed in the mitochondria. We also studied the ultrastructure of another Fibrophrys strain, Fibrophrys sp. E-1, which is different from the type strain of F. columna. A ladder-like pattern was recognized in the outer part of unidentified cytoplasmic membranes connected with the mitochondria. The unidentified cytoplasmic membranes were connected to the nuclear, lipid body, and mitochondrial outer membranes. We propose a new genus, Fibrophrys, and a new species, F. columna, based on these ultrastructural and molecular features.
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan; Toho Junior and Senior High School Affiliated to Toho University, Izumi-cho, Narashino, Chiba 275-8511, Japan.
authors.forename: Yuiki
authors.initials: Y
authors.lastname: Takahashi
authors.affiliation: Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan. Electronic address: yoshida.masaki.gb@u.tsukuba.ac.jp.
authors.forename: Masaki
authors.initials: M
authors.lastname: Yoshida
authors.affiliation: Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan.
authors.forename: Isao
authors.initials: I
authors.lastname: Inouye
authors.affiliation: Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan.
authors.forename: Makoto M
authors.initials: MM
authors.lastname: Watanabe
mesh_terms: D007564:Japan; D046529:Microscopy, Electron, Transmission; D010802:Phylogeny; D061005:Ponds / Q000469:parasitology*; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D013045:Species Specificity; D058009:Stramenopiles / Q000145:classification* / Q000166:cytology / Q000235:genetics / Q000648:ultrastructure
chemical_list: D012337:RNA, Ribosomal, 18S
keywords: Amphifilidae; Diplophrys; Fibrophrys columna sp. nov.; Fibrophrys gen. nov.; Phylogeny