Like other emydids (members of the family Emydidae),
Deirochelys karyotype consists of 2N=50
chromosomes. A 1996 study of various turtles'
mitochondrial DNA supported the partition of Emydidae into two subfamilies,
Emydinae and
Deirochelyinae, with
Deirochelys placed within the latter.
Deirochelys was reported to be the
sister genus to the rest of the subfamily, meaning it shares a common ancestor with the ancestor of all the other genera in Deirochelyinae. Alternative analysis by Stephens and Wiens found that under certain analyses
Deirochelys could instead be described as a sister taxon to Emydinae or indeed to the family Emydidae itself. The authors attributed this confusion to
long-branch attraction and concluded that
Deirochelys did indeed sit within Deirochelyinae. Spinks et al. (2009) also found
Deirochelys to be a sister to Emydidae under
maximum parsimony. It has been proposed that
Deirochelys and the painted turtles
Chrysemys are among the most
ancient emydids, having diverged from the rest of the emydids more than 24.4 million years ago. The genus
Deirochelys itself is thought to have evolved before the end of the
Clarendonian, over 10.3 million years ago. }} }} ==Species==