CHAMPAIGN, Ill., 8/18/21: Entomologists at the Illinois Natural History Survey (INHS) have discovered a new family of stoneflies, a finding that helps scientists studying the insects organize information and distinguish the species that need protecting.
This discovery is the first new stonefly family found in over 30 years and is part of a larger project to study how all groups of stoneflies in North America are related to one other. The new family, Kathroperlidae, in the insect order Plecoptera, is now the 17th stonefly family, according to INHS entomologist Ed DeWalt and Eric South.
Scientists study stoneflies because they are the most sensitive indicators of water quality among all animals. Stoneflies won’t survive if there is runoff into streams from crop fields or sewage treatment plants. They require clean waters to survive.
“Over time, stoneflies became eliminated from the landscape as their habitats degraded,” DeWalt said. “We can’t find 20 of the 80 species that we know of in Illinois. This decline is replicated across the country.”
The new family of stoneflies occurs in the western U.S. and Canada but is also known from South Korea. With the current wildfires and intense heat waves in the West, the three species that live in North America are likely at risk.
Using live samples that South and colleagues collected, South analyzed 800 gene sequences across all species to determine where members of the presumed family fell in relation to other stoneflies. They also studied high-resolution photographs of the samples to examine stonefly body parts compared between these species and their closest relatives.
“Based on the DNA, members of the new family turned out to be unique, falling outside of any grouping that we know of,” DeWalt said.
The genus Kathroperla, and its four species are now assigned to the new family described in the journal Insect Systematics and Diversity, outlining the premise and displaying all the evidence.
“The paper was written as a description and proposal of a new family, but I like to think of it as recognition of the genus Kathroperla and its elevation to the family level,” South said.
“He wanted to make sure that this placement of the family was a slam dunk,” DeWalt said of South. “He did a lot of extra work to ensure that there was no doubt in anyone’s mind that the genus belonged at a higher level.” The project took some five years to complete and was part of South’s dissertation. South recently joined the faculty at Lyon College, Batesville, Arkansas as assistant professor of Biology in the Natural Sciences Division.
In an ironic twist, after publishing their findings, an obscure paper by Nathan Banks from 1947 surfaced that had used the subfamily name Kathroperlinae, vaguely describing the subfamily within a different stonefly family named Perlidae. Under international rules, this is the first instance of use of Kathroperlidae, so the authorship of the newly elevated family is not attributed to South & DeWalt, 2021, but to Banks, 1947. The family name, its members, and distributions are summarized in DeWalt’s Plecoptera Species File (bit.ly/2VLz1i8).
This new stonefly family should draw the attention of other scientists and organizations that track this information and the groups that determine which insect species are imperiled and require conservation efforts.
Media contacts: Ed DeWalt, 217-649-7414, firstname.lastname@example.org; Eric South, email@example.com;