Biologists discover cross-dressing butterfly

PHILADELPHIA, Jan. 9 (UPI) -- Thanks to a keen-eyed volunteer at the Academy of Natural Sciences of Drexel University, researchers were able to get their hands on a rare two-sex butterfly.

"I thought: 'Somebody's fooling with me. It's just too perfect,'" museum volunteer Chris Johnson, a naturalist by trade, said of the moment he first spotted the butterfly. "Then I got goose bumps."

After isolating the butterfly, Johnson and his supervisor called for expertise. Jason Weintraub, a lepidopterist (butterfly expert) and the director of the museum's insects collection, confirmed the butterfly was half-female, half-male -- a relatively rare example of bilateral gynandromorphy.

Bilateral gynandromorphy is the phenomenon whereby animal species exhibit both male and female traits. Bilateral refers to the fact that the split in physical appearance occurs directly down the middle -- 50/50.

Weintraub also confirmed the specimen was common archduke (Lexias pardalis); this one arrived a pupae from a butterfly farm in Malaysia. The specimen's two left wings featured a dark brown background with yellow and white spots (female characteristics), while its two right wings boasted a darker green setting marked by a beautiful smear of fluorescent-like blue and purple coloring (male characteristics).

"Gynandromorphism is most frequently noticed in bird and butterfly species where the two sexes have very different coloration," Weintraub explained.

Scientists just last month spotted a half-male, half-female cardinal in Illinois.

"It can result from non-disjunction of sex chromosomes, an error that sometimes occurs during the division of chromosomes at a very early stage of development," Weintraub added.

The special specimen will be on display (preserved and pinned, not flying) at the museum from Saturday, January 17, through Monday, February 1.