In late 2014 the Brazilian state of Rio Grande do Sul added a monkey, a tapir, a weasel-like species called the tayra and 18 butterflies to its red list of endangered species.

One of those butterflies, a metallic-winged species known only as Stichelia pelotensis, was a bit of a mystery. It was first described in the 1950s, but all attempts to find it again in its original location had proven fruitless. The species had only been seen one time since then, a female found 250 kilometers from the first site. With this rarity in mind, the state government declared the butterfly critically endangered and warned that it faced extinction due to ongoing habitat loss in the region where it had first been seen.

A year later, we have good news about that lost butterfly. According to research published Nov. 28 in the journal Revista Brasileira de Entomologia, S. pelotensis has finally been found.

Researchers from Universidade Federal do Paraná and two other Brazilian institutions found the butterfly in a marshy grassland habitat about 17 kilometers from where it was observed in the 1950s. Their first sighting consisted of a single male. They had to wait nearly two months for their next observation, but patience paid off. This time they saw four additional males. A week later they saw both a male and a female.

As recounted in their paper, the male and female were seen feeding on a flowering plant called Eryngium elegans. “After feeding,” they wrote, “both specimens flew away in a rapid and erratic flight and were not seen again.”

Lead author Ricardo Russo Siewert, a biologist with Universidade Federal do Paraná, calls this “an important find” but says this is just the first step toward understanding this rarely seen species. We don’t know much about its behavior or ecological needs, including the host plant on which it lays its eggs. We don’t know how well the butterflies are doing, how many of them, or if they exist in other locations. “We still need to perform well-optimized inventories to search for other populations of this species,” he said.

Time is of the essence there. Siewert notes that “only 0.14 percent of these grasslands habitats in Rio Grande do Sul state is represented in preserved areas.” That tiny percentage doesn’t include the habitat where the butterfly was found. “The remaining field (or campos) habitats are losing area by the expansion of agricultural and silvicultural [forest crop] activities,” he says.

For now, Siewert considers this once-lost butterfly to still be critically endangered and in need of conservation. But at least the mystery of its existence has for now been solved.

Photo courtesy of Gustavo Crizel Gomes