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Alaska’s first new butterfly species in decades could be rare hybrid

  • Researchers have named the new species the Tanana Arctic (Oeneis tanana).
  • This is the first new butterfly species to be described from Alaska in 28 years, the authors say, and may be Alaska’s only endemic butterfly, which means that it is found nowhere else on earth.
  • The team thinks that the Tanana Arctic could have evolved from the offspring of two related butterfly species – the Chryxus Arctic and the White-veined Arctic – during the last ice age period.

This butterfly was hiding in plain sight.

In 2010, butterfly expert Andrew Warren was organizing specimens at the Florida Museum of Natural History, when he encountered a series of butterfly specimens that seemed to have been mistakenly labeled as the Chryxus Arctic butterfly (Oeneis chryxus).

A closer look revealed that the butterfly was larger and darker than the Chryxus Arctic, and had “different looking” genitalia. Moreover, the underside of the butterfly’s wings had white specks giving it a “frosted’ appearance”, according to a new paper in the Journal of Research on the Lepidoptera. Later, analysis of the butterfly’s DNA confirmed that the butterfly was most likely a new species.

Warren, a biologist at the University of Florida in Gainesville, and his colleagues, discovered many more specimens of these butterflies in local and private collections. All of them had been collected from around the Tanana River Basin in southeastern Alaska.

The researchers named the new species Tanana Arctic (Oeneis tanana) after the river. This is the first new butterfly species to be described from Alaska in 28 years, they say, and may be Alaska’s only endemic butterfly, which means that it is found only in Alaska and nowhere else.

The newly discovered Tanana Arctic butterfly is known only from the Tanana-Yukon River Basin. Photo by Andrew Warren.

Warren and his team posit that the Tanana Arctic could be a rare hybrid species.

The distribution of the Tanana Arctic butterfly seems to be restricted to the spruce and aspen forests of the Tanana-Yukon River basin. Most of this region never glaciated during the last ice age, about 28,000 to 14,000 years ago, the authors write, which could have provided a shelter for several species.

The team thinks that the Tanana Arctic could have evolved from the offspring of two related butterfly species — the Chryxus Arctic and the White-veined Arctic (Oeneis bore) — during this period. As the climate cooled further during the last ice age, the Tanana Arctic and White-veined Artic may have remained in the region, while the Chryxus Arctic may have been pushed south into the Rocky Mountains.

“Hybrid species demonstrate that animals evolved in a way that people haven’t really thought about much before, although the phenomenon is fairly well studied in plants,” Warren said in a statement. “Scientists who study plants and fish have suggested that unglaciated parts of ancient Alaska known as Beringia, including the strip of land that once connected Asia and what’s now Alaska, served as a refuge where plants and animals waited out the last ice age and then moved eastward or southward from there. This is potentially a supporting piece of evidence for that.”

The team believes that the new butterfly species could also serve as an early-warning indicator for environmental changes.

“This butterfly has apparently lived in the Tanana River valley for so long that if it ever moves out, we’ll be able to say ‘Wow, there are some changes happening,'” Warren said. “This is a region where the permafrost is already melting and the climate is changing.”

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