carabid beetle

Rare South American ground beetles sport unusual, likely multi-purpose antennal cleaners

The newly described Ball’s stange-combed beetle (*Nototylus balli*)
Photo by Terry L. Erwin

For 157 years, scientists have wished they could understand the evolutionary relationships of a curious South American ground beetle that was missing a distinctive feature of the huge family of ground beetles (Carabidae). Could it be that this rare species was indeed lacking a characteristic trait known in over 40,000 species worldwide and how could that be? Was that species assigned to the wrong family from the very beginning?

The species, Nototylus fryi, or Fry’s strange-combed beetle, is known so far only from a single, damaged specimen found in 1863 in the Brazilian State of Espíritu Santo, which today is kept in the Natural History Museum of London. So rare and unusual, due to its lack of “antennal cleaners” – specialised “combing” structures located on the forelegs and used by carabids to keep their antennae clean, it also prompted the description of its own genus: Nototylus, now colloquially called strange-combed beetles.

Left foreleg showing antennal grooming organs in the newly described Ball’s stange-combed beetle (*Nototylus balli*)
Photo by Terry L. Erwin

No mention of the structure was made in the original description of the species, so, at one point, scientists even started to wonder whether the beetle they were looking at was in fact a carabid at all.

Because the area where Fry’s strange-combed beetle had been found was once Southern Atlantic Forest, but today is mostly sugar cane fields, cacao plantations, and cattle ranches, scientists have feared that additional specimens of strange-combed beetles might never be collected again and that the group was already extinct. Recently, however, a US team of entomologists have reported the discovery of a second specimen, one also representing a second species of strange-combed beetles new to science.

Following a careful study of this second, poorly preserved specimen, collected in French Guiana in 2014, the team of Dr Terry Erwin (Smithsonian Institution), Dr David Kavanaugh (California Academy of Sciences) and Dr David Maddison (Oregon State University) described the species, Nototylus balli, or Ball’s strange-combed beetle, in a paper that they published in the open-access scholarly journal ZooKeys. The entomologists named the species in honour of their academic leader and renowned carabidologist George E. Ball, after presenting it to him in September 2016 around the time of his 90th birthday.

Despite its poor, yet relatively better condition, the new specimen shows that probable antennal grooming organs are indeed present in strange-combed beetles. However, they looked nothing like those seen in other genera of ground beetles and they are located on a different part of the front legs. Rather than stout and barely movable, the setae (hair-like structures) in the grooming organs of strange-combed beetles are slender, flexible and very differently shaped, which led the researchers to suggest that the structure had a different role in strange-combed beetles.

Judging from the shapes of the setae in the grooming organs, the scientists point out that they are best suited for painting or coating the antennae, rather than scraping or cleaning them. Their hypothesis is that these rare carabids use these grooming structures to cohabitate with ants or termites, where they use them to apply specific substances to their antennae, so that the host colony recognises them as a friendly species, a kind of behaviour already known in some beetles.

However, the mystery around the strange-combed beetle remains, as the scientists found no evidence of special secretory structures in the specimen studied. It turns out that the only way to test their hypothesis, as well as to better understand the evolutionary relationships of these beetles with other carabids is finding and observing additional, preferably live, specimens in their natural habitat. Fortunately, this new discovery shows that the continued search for these beetles may yield good results because strange-combed beetles are not extinct.

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Original source:

Erwin TL, Kavanaugh DH, Maddison DR (2020) After 157 years, a second specimen and species of the phylogenetically enigmatic and previously monobasic genus Nototylus Gemminger & Harold, 1868 (Coleoptera, Carabidae, Nototylini). ZooKeys 927: 65-74. https://doi.org/10.3897/zookeys.927.49584

New species of ground beetle described from a 147-year-old specimen

While new species are most commonly described based on recent field collections, undertaken at poorly explored places, some are identified in museum collections, where they have spent decades before being recognised as new to science. Such is the case of an unusually large and likely extinct ground beetle found at the Muséum national d’Histoire naturelle, Paris, whose story began in the distant 1860s with Dr. Eduard Graeffe’s trip to Samoa. Now, a century and a half later, the beetle is finally described by Dr. James K. Liebherr, Cornell University, USA, in the open access journal Zoosystematics and Evolution.

Much like the rest of the species within the genus, the beetle now going under the name Bryanites graeffi showed vestigial flight wings and other traits associated with flight-wing loss. However, at length of 16.2 mm it is the largest for the taxonomic group it is now assigned to. Although this may seem way too obvious for taxonomists to overlook, the beetle’s relatives are just as obscure. The Bryanites genus was previously known from two species represented by two specimens only, collected in 1924 from Savai?i Island by Edwin H. Bryan, Jr., Bernice P. Bishop Museum in Honolulu, during the Bishop Museum’s Whitney South Seas Expedition.

As a result, we now have three species representing an evolutionary radiation in Samoa, all known from single specimens collected long ago. The phylogenetics of these three species link them to other groups from Fiji and New Zealand.

What is the advantage of knowledge about species that existed some 90-150 years ago, but no longer? It might actually point us to the actual level of impact mankind has on natural ecosystems. The cause of the likely extermination of Bryanites graeffi might never be known with certainty, however, the colonization of many Pacific islands by the Polynesian rat has always been followed by the diminution or elimination of native insect species. Thus, we can add another likely victim to the list of species that have been adversely impacted by mankind’s commensal voyagers.

The species bears the name of its original collector to pay tribute to Dr. Graeffe and his hard work while collecting insects in the rain forest of Samoa well over a century ago .

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Original source:

Liebherr JK (2017) Bryanites graeffii sp. n. (Coleoptera, Carabidae): museum rediscovery of a relict species from Samoa. Zoosystematics and Evolution 93(1): 1-11. https://doi.org/10.3897/zse.93.10802

American scientists discover the first Antarctic ground beetle

Fossilised forewings from two individuals, discovered on the Beardmore Glacier, revealed the first ground beetle known from the southernmost continent. It is also the second beetle for the Antarctic insect fauna with living descendants. The new species, which for now is also the sole representative of a new genus, is to be commonly known as Ball’s Antarctic Tundra Beetle. Scientists Dr Allan Ashworth, North Dakota State University, and Dr Terry Erwin, Smithsonian Institution, published their findings in the open access journal ZooKeys.

The insect fauna in Antarctica is so poor that today it consists of only three species of flightless midges, with one of them having been probably introduced from the subantarctic island of South Georgia. The absence of biodiversity is considered to be a result of lack of moisture, vegetation and low temperatures.

Following their study, the authors conclude that the beetle must have inhabited the sparsely-vegetated sand and gravel banks of a meltwater-fed stream that was once part of an outwash plain at the head of a fjord in the Transantarctic Mountains. Plants associated with the extinct beetle include southern beech, buttercup, moss mats, and cushion plants, all typical for a tundra ecosystem. The species may or may not have been able to fly.

The closest modern relatives to the extinct species live in South America, the Falkland Islands, South Georgia, Tasmania and Australia. Tracking the ancient lineage of this group of beetles, known as the carabid beetle tribe Trechini, confirms that they were once widely distributed in Gondwana, the supercontinent that used to unite what today we recognise as Antarctica, South America, Africa, Madagascar, Australia, the Arabian Peninsula and the Indian Subcontinent. Ball’s Antarctic Tundra Beetle is also an evidence that even after Gondwana broke apart, the tundra ecosystem persevered in Antarctica for millions of years.

“The conflicting signals both in anatomical attributes and biogeography, and in ecological setting as well, leave open the question of relationships, thus giving us no alternative but to flag the species represented by fossil evidence through erection of new genus status, hence drawing attention to it and the need for further paleontological studies in Antarctica,” speak of their discovery the authors.

The new Ball’s Antarctic Tundra Beetle is scientifically identified as Antarctotrechus balli, where the genus name (Antarctotrechus) refers to its being related to the tribe Trechini, and the species name (balli) honours distinct expert of ground beetles Dr. George E. Ball, who celebrated his 90th birthday on 26th September, 2016.

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Original source:

Ashworth AC, Erwin TL (2016) Antarctotrechus balli sp. n. (Carabidae, Trechini): the first ground beetle from Antarctica. ZooKeys 635: 109-122. https://doi.org/10.3897/zookeys.635.10535