[A strange sighting] I want to know more! The mythical six-horned rhinoceros beetle, Diperix gerion! ~Part 2~

When did you first learn about Geryon?

I first learned about Geryon in 2019. At the time, I was a third-year student at a university in the UK, and I was in the middle of gathering materials for my graduation thesis. For my thesis, I needed materials on insect taxonomy from the 17th and 18th centuries, so I made numerous visits to the British Library, which holds many historical documents, and the reading section of the British Museum of Natural History, and read everything I could get my hands on.

One day, while I was reading "Illustrations of natural history" by Drew Drury in the library of the British Museum of Natural History, I suddenly came across an illustration of a strange-looking rhinoceros beetle that I had never seen before. At first glance, the beetle depicted looked similar to the Canthago rhinoceros beetle that lives in Indonesia, but it was clearly different, with long, well-developed proboscises. Looking back, this was the first time that Geryon and I had ever encountered each other.

Have you been chasing this mysterious beetle ever since?

To be honest, I didn't pay much attention to this species at the time. The reason is that the late 1700s was when the binomial nomenclature developed by Swedish biologist Carl von Linnaeus was gradually becoming more widespread, and it was still the dawn of taxonomy and a time of chaos. The specimens depicted in catalogs at the time often had missing parts filled in with imagination, and the skill of natural history artists was not as high as it is today, so parts of the body were often depicted with more emphasis than in reality.

Of course, in those days, the infrastructure wasn't as developed as it is today to travel overseas to collect specimens as easily, and even if people did travel by boat, it was a life-risking voyage on a large sailing ship, with the fear of disease and other dangers. The number of specimens brought to Europe from overseas was not that large, and most were in poor condition or had many chips. Therefore, I unconsciously assumed that Gerion's natural history illustration was an exaggerated depiction of the Canthargo rhinoceros beetle or a closely related species.

After that, I wrote my graduation thesis, which was accepted and I was able to graduate. After returning to Japan and starting my career as a specimen dealer, the strange insects I had seen in Drury's catalogue had completely disappeared from my consciousness.

What was the trigger that changed your perception of it as an "exaggerated natural history painting" to "a real, unknown rhinoceros beetle"?

What reminded me of this insect was when, last spring in 2023, a German dealer I'm friendly with sent me a picture asking, "Do you have this specimen?" The picture showed a strange-looking rhinoceros beetle I'd never seen before. I collect a variety of insects, but rhinoceros beetles are my favorite. So, I prided myself on having accumulated a fair amount of knowledge about rhinoceros beetles, but no matter how much I dug through my mental database, I couldn't find anything about this beetle.

Still, it's said that there are currently around 2,000 species of rhinoceros beetles in the world, and there are still many species I don't know about. There are many rare species, especially small rhinoceros beetles from Australia and Asia, with no photographs of them reported in the literature, and naturally, there are many species for which there are almost no hits when searching online. So I assumed that the species I had been sent in the photo of was one of those.

So I asked him what the species name was, and he replied, "It says 'Dipelicus geryon' on the label." I had never heard of that name before, so I typed "Dipelicus geryon" into the search bar to find out more, and searched for images, but I couldn't find a single image of a specimen that looked like it. Instead, I found an image of a tasteful, old-looking natural history illustration that I'd seen somewhere, probably drawn around the 18th century.

This was the strange-looking rhinoceros beetle I had seen in a Drury catalogue back when I was a student. The beetle depicted there looked exactly like the one in the photo the dealer had sent me. Yes, this was not a beetle I had never seen before.

What is the history of such a precious Geryon specimen?

It originally belonged to the collection of the great German collector Gerhard Pross, who is known as one of the most powerful collectors of his time. However, due to his advanced age, he has stopped collecting in recent years and has begun selling off his vast collection.

However, selling such a large collection requires an immense amount of time and effort, so a trusted dealer is acting as an intermediary. The labels that came with the items only contained the scientific name of Gerion and simple handwritten information that simply read "Java." These labels were added by Pross in recent years, and are so simple and rough that they could almost be called "notes," made on paper that is clearly just a section cut out of copy paper.

Pross said he had previously purchased this specimen from someone. His vast collection includes many specimens left behind by predecessors in Germany, and many of the specimens have worn labels and attachments, indicating that they have passed through the hands of various collectors over several generations.

This specimen, like many others, is missing most of its legs and is in poor condition. It did not have the original label with the date of collection, so the exact collection date is unknown, but given its condition and the fact that it was in Pros' possession, it is unlikely to be a new specimen obtained recently.

I never thought I would have the strange rhinoceros beetle I saw in the Drury catalogue that day in my hands... I never thought something like that would ever happen, but it turns out that things that seem impossible can actually happen quite easily.