Son of Luna Lovegood and Rolf Scamander, twin of Lorcan.
"Lysander" = Greek name meaning "release of a man"
It's interesting to think about when exactly Lorcan and Lysander were born. According to A Year in the Life, Luna had children "considerably later" than Harry/Ginny and Ron/Hermione. Harry's last child was born in 2008. However, by 2014, Rita Skeeter is unkindly theorizing that the twins are ‘too disturbed to be seen in public’ (Pm/QWC), which seems a very odd statement to make about infants. If Lorcan and Lysander are old enough to be considered possibly disturbed, they have to be at least three or four years old, but that would place their birthday in 2010 or 2011, which is not really "considerably" later than 2008. Then again, this is J.K. Rowling and maths...