Lionesses can have manes too

Bridget, a lioness at the Oklahoma City Zoo, is sporting an unusual look. The 18-year-old female has grown a mane—although her extra tresses resemble more a beard than a typical male lion's mane. The zoo has been calling it her "mini-mane."

Though rare, maned lionesses are not unheard of. In Botswana's Okavanago Delta, maned lionesses are regularly spotted, likely the result of a genetic anomaly shared by related animals.

Embryos that were disrupted either at conception or during gestation likely caused the genetic mutation, Luke Hunter, president of the big-cat conservation group Panthera, told National Geographic in 2012. "Alternatively, and perhaps more likely, the problem may have occurred during gestation if the fetus was exposed to increased levels of androgens—male hormones such as testosterone," Hunter says.

Male lions typically start growing manes at about a year old, when they begin producing testosterone. Some males, like the infamous Tsavo man-eaters, are maneless, but a 2006 study found they may have evolved this feature to keep cool in blistering heat.
https://news.nationalgeographic.com/2018/02/animals-lions-manes-zoos-genetics-spd/