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''Ixos'' is a songbird genus in the bulbul family, Pycnonotidae. It provisionally contains the following species:〔Gregory (2000), Pasquet ''et al.'' (2001), Moyle & Marks (2006)〕 * Streaked bulbul, ''Ixos malaccensis'' * Nicobar bulbul, ''Ixos nicobariensis'' * Mountain bulbul, ''Ixos mcclellandii'' (provisionally placed here) * Sunda bulbul, ''Ixos virescens'' (type species) ==Systematics and taxonomy== The mountain bulbul and Sunda bulbul – formerly ''H. mcclellandii'' and ''H. virescens'' – are provisionally placed in ''Ixos'' until the genus limits in bulbuls are firmly established. They are often included in ''Hypsipetes'' but this is an old error that was promoted in modern times by the Sibley taxonomy. In fact, ''I. virescens'' is the type species of ''Ixos'', and though some sources advocate a complete merger of the two genera – and even the entire "''Hypsipetes'' group" of bulbuls, which also includes ''Hemixos'', ''Iole'', ''Microscelis'' and ''Tricholestes'' –, being the oldest genus name ''Ixos'' would apply to all of them, rather than ''Hypsipetes'' as is often believed.〔 The most drastic course hardly appropriate however, since ''Alophoixus'' and ''Setornis'' cannot be excluded from the "''Hypsipetes'' group", and an all-out merge would turn the resultant "genus" ''Ixos'' into an ill-defined "wastebin taxon". The erroneous inclusion of ''I. virescens'' in ''Hypsipetes'' has caused the Nicobar bulbul to be listed under its invalid junior synonym ''H. nicobariensis'' rather than the valid names ''H. virescens'' or ''I. nicobariensis''.〔 The streaked bulbul, meanwhile, seems to be closer to ''Hemixos'' and perhaps ''Iole'' and maybe the hook-billed bulbul (''Setornis criniger'') than to ''Hypsipetes''. Thus, given the lack of study of the Sunda bulbul's affiliations, ''Ixos'' might eventually be reduced to the core group around ''I. virescens'' and kept well distinct from ''Hypsipetes''. Or it may be that some species (such as ''I. malaccensis'') are be split off into a distinct genus (for which no scientific name exists yet), while ''Hypsipetes'' is merged into the core group of ''Ixos''.〔Pasquet ''et al.'' (2001), Moyle & Marks (2006)〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Ixos」の詳細全文を読む スポンサード リンク
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