MOSCOW, Dec 7 (Reuters) - Natalya Yarygina, widow of former Olympic wrestling  champion Ivan Yarygin, has become the first woman to be voted on to the  executive board of the sport's international ruling body FILA.     "It was a unanimous decision," Russian wrestling chief Mikhail Mamiashvili told Reuters on Friday from Patras, Greece -- site of this week's world  championships.     "It is really a landmark case for international wrestling as Natalia became the first woman to be included into FILA's hierarchy since it was formed  almost 100 years ago."     Yarygina will be responsible for the women's competition which is set to make  its Olympic debut at the 2004 Games in Athens.     Ivan Yarygin, who won Olympic gold medals for the Soviet Union in freestyle  wrestling in 1972 and 1976, was killed in a car accident four years ago.