Kourtney Kardashian has revealed the name of her newborn son. The Kourtney & Khloe Take the Hamptons star posted a photo on Instagram Sunday of the infant's little hand within her own. "Madly in love with my little Reign Aston Disick," she captioned the image. Kardashian and her longtime boyfriend Scott Disick welcomed Reign Aston on December 14, which was ironically the same date of her son Mason's fifth birthday. Kardashian, 35, and Disick, 31, also have a two-year-old daughter Penelope. Kourtney & Khloe Take The Hamptons premiered November 2 and airs Sunday nights at 9PM ET\/PT on E!.