Little beetle, big questions
California species rediscovered after half a century on governor Brown's ranch
A small beetle can raise some very big questions.
In 2021, Professor Kipling Will of the University of California at Berkeley was collecting on the ranch of former governor Jerry Brown when he encountered a little beetle drawn to an ultraviolet light. He recognized it as the genus Bembidion, which has about 275 species in the U.S. and Canada, but it didn’t look like any of the species he was familiar with. Its pronotum, the segment immediately behind the head, was unusually broad and convex and, as Bembidion go, it was a big one, 4.4 to 5 mm in length.
Bembidion brownorum. From Maddison, Sproul and Will (2023), ZooKeys 1156: 87-106. CC by 4.0
He subsequently collaborated with Dr. David Maddison of Oregon State University, a noted authority on the genus, and evolutionary biologist Dr. John Sproul of the University of Nebraska, Omaha, to investigate further. They scoured natural history collections in search of additional material. Although successful, what they found was surprising for two reasons. First, there weren’t very many of these beetles in museum collections, only 21. And second, they were from far-flung localities in California, from the Central Valley to the LA Basin, indicating that this is, or at least was, a rather widespread species.
Both morphology and DNA data quickly led them to conclude that this was a species new to science. It’s an attractive beetle whose dorsal surface is only slightly metallic with faint spots. Their treatment of the beetle is a wonderful example of taxonomy done well. It synthesizes evidence from morphology and DNA, analyzes the relationship of the new species to others, and thoughtfully considers available evidence of geography, habitat, and population trends. Adding a little glitz to their discovery, they named it Bembidion brownorum in honor of governor Jerry Brown and his wife Anne who have graciously invited biologists onto their property to study its biodiversity. It never hurts to show gratitude—or to kiss up to the powerful. Well played, professors.
Among vertebrate animals, about 90% of those rediscovered after a long period of time turn out to be threatened species, as may well be the case for this little beetle. Locations where it was collected from the 1920s to 1940s have undergone significant development. This species is one worrisome data point in an alarming trend in insect populations. Researchers in Germany reported a 75% decline in the biomass of flying insects over a 27-year period in protected nature preserves. Another study noted a 30% decline in the diversity of insect species in samples.  And researchers warn that 40% of insect species may be vulnerable to extinction in coming decades. They conclude that the driving factors include habitat loss, including intensive agriculture and urbanization; pathogens and invasive species; pollution, including fertilizers and pesticides; and climate change.
There could not be a worse time to neglect taxonomy, the most fundamental of the sciences that explore species, their diversity and their evolutionary history. It is increasingly clear that the time remaining to explore and inventory earth’s species is rapidly disappearing.  But instead of making commonsense investments in taxon experts, descriptive taxonomic studies, and expansion of natural history museum collections, taxonomy is being largely relegated to DNA data. Such data is uniquely important among sources of evidence in systematic biology but, like all data, has serious limitations.
Trends in taxonomy done to its highest standards and as an independent science—as opposed to being done to simply make species identifiable for other biologists—are as alarming as the decline in insect populations. Taxonomists are not being replaced in kind as they retire. Endowed chairs specifically established for taxonomy are filled by researchers who do not do taxonomy. And studies that include high-quality treatments of morphology find it increasingly difficult to locate funding. In the middle of a biodiversity crisis, facing an uncertain future, there could not be a worse time to neglect taxonomy.
This little beetle is a reminder of what we don’t know about species and what is happening to them. And a reminder, too, that historically California, with its incomparable diversity of habitats, has been a model of excellence in species exploration and taxonomy.  Just the kind of leadership we desperately need to reassert now.
References
Hallmann, Caspar A., Ssymank, Axel, Sorg, Martin, and Jongejans, Eelke (2021) Insect biomass decline scaled to species diversity: General patterns derived from a hoverfly community. PNAS 118 (2) e2002554117.
Maddison, David R., Sproul, John S., and Kipling Will (2023) Re-collected after 55 years: a new species of Bembidion (Coleoptera, Carabidae) from California. ZooKeys 1156: 87-106.
Sanchez-Bayo, Francisco and Kris A. G. Wyckhuys (2019) Worldwide decline of the entomofauna: A review of its drivers. Biological Conservation 232: 8-27.
That New Zealand connection would make one suspicious at the outset. It is interesting when rare species turn out to have rarely collected, specific habitats. In searching out rare species, there is nothing like an experienced taxon specialist. One of my students was collecting in Costa Rica where decades of general collected had never turned up a single specimen of the family he studied. Given his special knowledge, he was able to collect five species in a few days, some of them new species, much like the grad student you mention. Cheers.
It's always fun to rediscover a "lost" species, although it sometimes doesn't involve the detailed work you describe. Sometimes it's just another specimen, often from somewhere else. Many years ago I described a harvestman species, Fumontana deprehendor, from the Great Smoky Mountains National Park (the name means "one who takes by surprise from the Smoky Mountains"). I first found the critter in the collections of the Field Museum in Chicago where it had rested unrecognized for decades. Immediately I saw that it was something very strange--a member of a family that was restricted to the southern hemisphere, and more specifically abundant in New Zealand. What was it doing in North Carolina? My first thought was that it was mislabelled, but then i saw that it had been collected by Henry Dybas, a very meticulous collector. So I visited the same general area of the park and sure enough, found some more, enough to describe the species and hypothesize about its evolutionary position. Years later I got one more from nearby Joyce Kilmer Memorial Forest, then a couple of decades passed. Finally, a graduate student at San Diego University got interested, and by assiduous field work found that the species had a specific habitat--the insides of rotting hemlock logs. Armed with that hypothesis, he collected many specimens from Georgia and Alabama to the North Carolina/Virginia border and found four genetically distinct populations, separated by well-known biogeographic barriers like the French Broad River. Subsequent phylogenetic work has supported the hypothesis of its New Zealand affinities, and indeed it seems to be the most basal species of that family. It can be equally exciting to find a second species of a long-monospecific genus. That's happened to me twice, but is a story for another time. Thanks again for a fascinating article that helped you to make a point of wider importance.