Wikipedia
Mandelo
A mandelo (or Mandalo), also known as a “ Cocktail Grapefruit” (though it is not technically a grapefruit), is a white-fleshed trispecific citrus hybrid between a Frua hybrid mandarin (Dancy mandarin × King tangor) and a Siamese Sweet pommelo, making it 1/4 King tangor, 1/4 Dancy tangerine, and 1/2 Siamese Sweet Pommelo.
Mandelo stands for its ancestors mandarin and pommelo, and was developed in Riverside, California in 1966.
Due to its tenderness and high seed content, the mandelo has not achieved great commercial success, but its unique flavor, early and long season, and prolific nature has led to an increasing popularity in backyard orchards in southern California.