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Two New Species of Butterfly Accidentally Discovered in Eastern USA

The discovery of a new butterfly species is very rare nowadays, so it’s even more remarkable that Texas researchers have discovered not just one, but two new species.

“It was completely unexpected,” said Dr. Nick Grishin, a professor of biochemistry at the University of Texas Southwestern Medical Center. “We were studying genetics of these butterflies and noticed something very odd. Butterflies looked indistinguishable, were flying together at the same place on the same day, but their DNA molecules were very different from each other. We thought there was some kind of mistake in our experiments.”

Intricate satyr (A) and Carolina satyr (B) are very similar in wing patterns despite being more evolutionarily distant from each other, but south Texas satyr (C) is distinguished by smaller eyespots are wavier lines, while being much closer related to Carolina satyr. Photo by Nick V. Grishin.

But there was no mistake. While the wing patterns in the two groups were indeed very similar, inspection of the genitalia revealed profound differences. Males and females from one cluster had larger and paler genitalia, and males and females from the other cluster possessed smaller and darker genitalia, among other numerous distinctions.

It became clear that the researchers were dealing with two species, which were not even very closely related to each other, even though their wing patterns are very similar. The study was published in the open access journal ZooKeys.

One of these species is a well-known Carolina satyr (Hermeuptychia sosybius), discovered two centuries ago in 1793. The butterfly is brown and small — just over an inch in wingspan — with eyespots along the edge of its wings. It is one of the most common eastern US butterflies and a usual denizen of shaded, wooded areas.

The other species was new. It has been named “intricate satyr” (Hermeuptychia intricata) because of the difficulty in recognizing this very distinct species and its intricate ventral wing patterns, according to the researchers. Initially discovered in Brazos Bend State Park in East Texas, the intricate satyr is widely distributed all over the eastern USA in several states, including Florida and South Carolina.

This is an evolutionary tree constructed from DNA sequences that shows three distinct clusters corresponding to three satyr species. Carolina satyr and south Texas satyr are closer related, and intricate satyr is more distant from both of them. Butterflies are shown on the right. Credit: Nick V. Grishin (tree), Vitaly Charny (Intricate and Carolina Satyrs, identification of Intricate Satyr is provisional without genitalia inspection), and Jan Dauphin (South Texas Satyr).

Being curious about the genetic makeup of these satyrs, the researchers decided to investigate DNA sequences and the genitalia of satyr populations from south Texas, and it immediately paid off. These populations turned out to be another new species, named “south Texas satyr” (Hermeuptychia hermybius).

Interestingly, the south Texas satyr is a close relative of the Carolina Satyr, but the intricate satyr is rather distant from both of them.

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A new Hermeuptychia (Lepidoptera, Nymphalidae, Satyrinae) is sympatric and synchronic with H. sosybius in southeast US coastal plains, while another new Hermeuptychia species – not hermes – inhabits south Texas and northeast Mexico

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