Discovery of new species ends century of neglect for parasitic wasps

UAlberta researchers identify six new North American species—the first such discovery in more than 100 years.


(Edmonton) Researchers at the University of Alberta have identified six new North American species in the parasitic wasp genus Ophion, within an also newly defined species group—the first such discovery in more than 100 years.

Ophion is a genus of nocturnal solitary wasps that are found worldwide but are especially diverse and common in temperate regions. Because Ophion are nocturnal, they lack the bright colours common in other wasps, and have large eyes and long antennae. The adult females are parasitic, laying their eggs inside caterpillars, where the larval wasps then feed on the caterpillar, ultimately killing it.

The last time a new Ophion species was identified was in 1912, increasing the number of known species in North America at that time to 11. Scientists have long known that the actual diversity is much higher, but it took 102 years for any additional species to be described. 

"The main reason for this is that everyone has assumed that Ophion are just too difficult to tell apart," explains Marla Schwarzfeld, an entomologist who recently completed her PhD at the U of A. "Museum collections are full of unidentified Ophion, but nobody has wanted to face the challenge of sorting them out."

The author of one of the species described in 1912, Claude Morley, summed up the challenge: "Without abundant material it were ridiculous to attempt a wide revision of these insects; and ... a mass of this material causes one's courage to sink at the sight of so uniform and apparently characterless a group."

However, with the advent of new taxonomic tools, it is no longer necessary to rely solely on the challenging morphology of the group. Schwarzfeld and her PhD supervisor, Felix Sperling, used a combination of molecular and morphometric analyses to define a new species group within Ophion, and to delimit and describe the six new species within this group. “This is just a tiny proportion of the number of species that are out there,” says Schwarzfeld. “I predict that the final count will be over 100 species in North America.”

The molecular work involved analyzing three different genetic markers; the morphometric analyses included looking at the arrangement of veins in the insects' wings, along with a more traditional approach of measuring various body parts. “Some species looked quite distinctly different from each other, whereas others were separated by subtle characteristics,” explains Schwarzfeld.

“The exciting part about this work is that these techniques all gave remarkably congruent results, which gives us a lot of confidence in these new species,” she says. “This takes a lot of the guesswork out of describing species, and will be a really valuable toolkit for studying additional species of Ophion, as well as species in other morphologically challenging groups.”

The study, including the new descriptions, was published in the open-access journal ZooKeys.