Examinando por Autor "Yamasaki, Hiroshi"

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On the genus Dracoderes Higgins & Shirayama, (1990) (Kinorhyncha: Cyclorhagida) with a redescription of its type species, and a description of a new species from Spain
(Taylor & Francis, 2012-02-06) Sørensen, Martin V.; Herranz, María; Min, Won-Gi; Rho, Hyun Soo; Yamasaki, Hiroshi; Sánchez, Nuria; Pardos, Fernando
The type species of Dracoderes, D. abei, is redescribed based on specimens from several localities in Japan and Korea, and a new species of the genus, Dracoderes gallaicus sp. nov., is described from the coast of Spain in Western Europe. The new species is distinguished by the presence of lateral accessory spines on segment 5. In addition, preliminary diagnostic notes on a yet undescribed species from the Okinawa Region, Dracoderes sp. 1, are provided. Based on new information from D. abei and D. gallaicus sp. nov., an emended genus diagnosis for Dracoderes is proposed. The study includes the first scanning electron microscopical data for species of Dracoderes, and presents for the first time detailed information about head morphology and scalid arrangement, new data about the arrangement of the neck placids, and demonstrates the presence of feebly visible nephridial pores. The new information may be of phylogenetic significance, and is expected to contribute important data for future phylogenetic analyses of the kinorhynch interrelationships.
Phylogeny of Kinorhyncha Based on Morphology and Two Molecular Loci
(Public Library of Science, 2015-07) Sørensen, Martin V.; Dal Zotto, Mateo; Rho, Hyun Soo; Herranz, Maria; Sánchez, Nuria; Pardos, Fernando; Yamasaki, Hiroshi
The phylogeny of Kinorhyncha was analyzed using morphology and the molecular loci 18S rRNA and 28S rRNA. The different datasets were analyzed separately and in combination, using maximum likelihood and Bayesian Inference. Bayesian inference of molecular sequence data in combination with morphology supported the division of Kinorhyncha into two major clades: Cyclorhagida comb. nov. and Allomalorhagida nom. nov. The latter clade represents a new kinorhynch class, and accommodates Dracoderes, Franciscideres, a yet undescribed genus which is closely related with Franciscideres, and the traditional homalorhagid genera. Homalorhagid monophyly was not supported by any analyses with molecular sequence data included. Analysis of the combined molecular and morphological data furthermore supported a cyclorhagid clade which included all traditional cyclorhagid taxa, except Dracoderes that no longer should be considered a cyclorhagid genus. Accordingly, Cyclorhagida is divided into three main lineages: Echinoderidae, Campyloderidae, and a large clade, ‘Kentrorhagata’, which except for species of Campyloderes, includes all species with a midterminal spine present in adult individuals. Maximum likelihood analysis of the combined datasets produced a rather unresolved tree that was not regarded in the following discussion. Results of the analyses with only molecular sequence data included were incongruent at different points. However, common for all analyses was the support of several major clades, i.e., Campyloderidae, Kentrorhagata, Echinoderidae, Dracoderidae, Pycnophyidae, and a clade with Paracentrophyes + New Genus and Franciscideres (in those analyses where the latter was included). All molecular analyses including 18S rRNA sequence data furthermore supported monophyly of Allomalorhagida. Cyclorhagid monophyly was only supported in analyses of combined 18S rRNA and 28S rRNA (both ML and BI), and only in a restricted dataset where taxa with incomplete information from 28S rRNA had been omitted. Analysis of the morphological data produced results that were similar with those from the combined molecular and morphological analysis. E.g., the morphological data also supported exclusion of Dracoderes from Cyclorhagida. The main differences between the morphological analysis and analyses based on the combined datasets include: 1) Homalorhagida appears as monophyletic in the morphological tree only, 2) the morphological analyses position Franciscideres and the new genus within Cyclorhagida near Zelinkaderidae and Cateriidae, whereas analyses including molecular data place the two genera inside Allomalorhagida, and 3) species of Campyloderes appear in a basal trichotomy within Kentrorhagata in the morphological tree, whereas analysis of the combined datasets places species of Campyloderes as a sister clade to Echinoderidae and Kentrorhagata.