He will be responsible for books content in both print and online editions of the title, a press release from the publisher said.
MacArthur, who has worked for TMG for three years, previously worked for the Times and Sunday Times and handled serialisations of books for the titles.
The group has also appointed Harry de Quetteville as people editor.
In his new role de Quetteville will oversee the obituaries, court, social and weather sections across the daily, Sunday and online editions.
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