People.com said Friday the unidentified representative offered no explanation for the newborn's name, but the Web site did explain that Tobias is the formal version of Maguire's first name.
The 34-year-old star of the "Spider-Man" trilogy is married to 32-year-old Jennifer Meyer. The couple met in 2003 and has a 2-year-old daughter, Ruby.
Otis Tobias Maguire was born May 8.
Copyright 2009 by United Press International.