A stingray that got pregnant at a North Carolina aquarium this winter despite not having shared a tank with a male of her species for many years has died.

The Aquarium and Shark Lab in Hendersonville said on Facebook late on Sunday that the stingray, Charlotte, died after getting a rare reproductive disease. It did not go into further detail.

The aquarium, which is in the Blue Ridge Mountains, announced in February that Charlotte had become pregnant despite not having shared a tank with a male stingray in at least eight years.

But it said in late May that she was suffering from a rare reproductive disease and announced in early June that she had not given birth and was no longer pregnant.

The pregnancy was thought to be the result of a type of asexual reproduction called parthenogenesis, in which offspring develop from unfertilized eggs, meaning there is no genetic contribution by a male.

The rare phenomenon can occur in some insects, fish, amphibians, birds and reptiles, but not in mammals. Documented examples have included California condors, Komodo dragons and yellow-bellied water snakes.