After being mostly neglected for more than a hundred years, a group of digger wasps from Australia has been given a major overhaul in terms of species descriptions and identification methods. This approach has led to an almost 50% rise in the number of recognized species of these wasps on the continent. The study was published in the open access journal ZooKeys.
Members of the wasp genus Sphex can be found in almost every area of the world (in the U.S. they go by names like “great golden diggers” or “great black wasps”), and two researchers from the Museum für Naturkunde in Berlin, Thorleif Dörfel and Dr. Michael Ohl, have now reexamined the species diversity of Sphex in Australia.
More than a century has passed since the last revision of this group in the Down Under. Using pinned, dried individuals from museum collections all over the world, Dörfel and Ohl inspected more than 900 specimens and recorded the morphological characters that they deemed most useful for species differentiation.
The genus Sphex has a very different lifestyle from the one that most people think about when they hear the word “wasp.” These wasps are solitary, and each female constructs a separate, subterranean nest for her offspring, which she fills with grasshoppers (or other insects, depending on the wasp species) that have been paralyzed by a sting. The wasp larvae then eat the grasshoppers and other insects. These wasps avoid contact with humans and generally do not show aggressive behavior towards them.
With 23 species known from Australia before this study, the number has now risen to 34. Most of these newly discovered species come from large quantities of material which had not been identified down to species level before. Dörfel and Ohl’s work also provides an up-to-date identification key, both in a regular and in an interactive form, that covers all known Australian species of the genus. Specifically designed to be easily usable and containing many helpful images, it can be utilized by anyone with even minimal prior training.
“Many insect groups are in urgent need of a revision or reclassification,” explained Dörfel. “Our understanding of ecosystems depends on the ability to identify the species that are a part of them. The focus of this study was merely a single continent, but we are currently preparing a follow-up project in which we plan to examine representatives of this wasp genus from every major geographic area. Hopefully, this is going to help everybody who works on these animals, whether now or in another one hundred years.”
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