For such a tiny fly, Marleyimyia xylocopae sure can cause a ruckus. It’s handsome, having apparently evolved to mimic the carpenter bee's striking yellow-on-black coloration. It has big eyes, and a brilliant blue-green glow to its wings.

At least, so say the photos—the only evidence of its existence. In 2015, taxonomist Stephen Marshall was trying to collect a specimen of the beautiful fly in South Africa's Ndumo game reserve. (He had it in a bottle, but fumbled as he was putting on the lid.) So on October 5, 2015, Marshall and another scientist, Neal Evenhuis, broke from scientific dogma and gave it a name using photographs alone.

In biology, the specimen is sacred. From it you get morphology, you get DNA. This is how zoology works. Scientists find what they think is a new species, bottle the specimen up, and write a paper, noting in what university or natural history museum other scientists can find the specimen. So what Marshall and Evenhuis did was, for a vocal group of scientists, a big no-no. The pair not only named a new species without a specimen, but wrote that photography-based taxonomy was increasingly important in this age of high-res imaging. The title of their study? “New Species Without Dead Bodies: a Case for Photo-Based Descriptions.”

“We deliberately titled the paper to stimulate discussion,” says Marshall. “And we knew there would be some initial responses to the effect of ‘Harumph, that is just not the way it is done!’”

They were right. Rage from angry taxonomists rained down on social media, opening up a massive rift among taxonomists. That may sound petty and silly to you. But the implications for science are weirdly profound—because according to the rules of zoology, Marshall and Evenhuis did nothing wrong.

Ain’t No Geek Fight Like a Taxonomy Geek Fight

Things in the taxonomy world really got boiling this July, when Nature published an article about how Pokemon Go could “transform taxonomy.” (Hey, remember Pokemon Go?) Lots of players were out and about, wandering with a camera in their hand. They just might snap photos of new species, but—based on the backlash to Marshall and Evenhuis' paper—taxonomists would balk at the idea of naming the critter with photos alone.

The article did not suit a man named Thomas Pape, president of the group that publishes the International Code of Zoological Nomenclature, the guidelines for naming species. He, along with 34 signatories, came to the pair's defense in Nature: For Marshall and Evenhuis, he wrote, the formal species name "was based on material that supported their conclusions and an explanation of the circumstances to justify naming a species without an extant type." The International Code of Zoological Nomenclature allows biologists to name species in the absence of physical specimens, so what Marshall and Evenhuis did was kosher. The species, Pape wrote, was legit. Peer-review legit.

That response spawned a particularly rancorous thread in the Facebook group Natural History Collections, where pro- and anti-photo taxonomists descended into name-calling and snark. Eliécer Gutiérrez and Christopher Mah, both of the Smithsonian Institution National Museum of Natural History, got into a particularly testy back-and-forth over the merits of photo-based taxonomy. "This is an option for people who need more options than just a dead bone somewhere," Mah wrote. "If you don't wish to do this..then don't."

"Crypotozoologists [sic] salute you, Dr. Mah!" Gutiérrez replied. Cryptozoology is the “science” of hunting for mythical creatures like the Loch Ness monster.1

If you thought the fight would stick to social media, you don't know how scientists operate. Anti-photo taxonomists penned a formal response to the Pape correspondence, “Photography-Based Taxonomy Is Inadequate, Unnecessary, and Potentially Harmful for Biological Sciences”—complete with almost 500 signatories. Their idea is that a 2-D representation of an animal can never be as reliable as a physical specimen you can hold. “Good photographs can show important aspects of the appearance of an animal, but many characteristics of the animal are impossible to be adequately, or at all, represented on photographs,” says Gutiérrez, a co-author. “For example, very small body features, aspects of the animal’s internal anatomy and, of course, its DNA.”

On ResearchGate, a social network for scientists to share and comment on research, the comment section on the paper got ... heated. Pondered one, perhaps hyperbolically: "If PBT (photography-based taxonomy) is to be accepted, why not go a step forward and accept DBT (drawing-based taxonomy)?"

A Picture Is Worth a Thousand Controversies

Flame wars aside, opponents of photo-based taxonomy aren't so much worried about a fly in South Africa. What they actually fear is that the idea could ripple through taxonomy. “PBT is basically a Pandora’s box, whose dangers surpass by far any possible benefits,” writes Luis Ceríaco of the National Museum of Natural History and Science, Lisbon, in an email. “Any unscrupulous taxonomist (which unfortunately are not as rare as we wish they would be) can simply manipulate a photograph and literally ‘create’ a different species—adding more scales, different colors, exaggerated body sizes, etc.” Sure, to Ceríaco's knowledge, that hasn't happened yet. But it could, the anti-photo crowd argues.

They're not totally paronoid. Really, it’s quite easy for amateur taxonomists to not only write a paper and submit it to some obscure journal, but to start their very own journal. “Technically if you want, you can make your own publication,” says Pape. “You can name your own species. The reason you don't do it is that you would make a fool of yourself.”

But the solve for that problem isn't campaigning against the use of images, says Doug Yanega, a commissioner of the International Commission on Zoological Nomenclature. "One thing would address their worries here and in all other possible abuses of taxonomy: making a peer review process mandatory for all new taxon descriptions,” he says. And better, more open peer review to replace a broken system. "Cronyism, anyone?" says Yanega. "Cliques, anyone?"

Until the taxonomy community resolves those issues, photo-based species can play an important role in the field. “We all dearly want physical specimens—nice, good, well-preserved physical specimens that will be available to all of us for studies,” says Pape, the ICZN president. But that’s in a perfect world. In the realistic world of fieldwork, things get messy. In Marshall and Evenhuis’ case, their slippery subject had wings. Miles deep in the sea, sometimes ROV operators can only manage to record video of their subjects. And good luck collecting jellyfish and other gelatinous critters: They’ll pretty much melt in a net.

So field biologists take what they can get. And exceedingly rarely they’re forced to claim a new species based on photos alone. “If photographs are of a high quality, then we can make that assessment, and then we can use the specimen that is photographed as a proxy, so to speak, for the preserved specimen,” Pape says.

This is particularly important for conservation. Earth is losing its biodiversity at an astonishing rate, and naming species is vital for saving them, because it’s tough to get legislation on the books to protect a species if you don’t have a name. Work fast enough and you may just save the species you’ve discovered. Sometimes that means working with specimens, and sometimes it means working with photos and another digital captures.

Consider one study from 2013. Scientists working in Oman captured photos and sound recordings—but never a specimen—of what they determined to be a new species of owl. In their paper they devoted a whole section to justifying their naming of a new species without a specimen. Scaling cliffs to collect the bird, which only emerges at night, would have been nightmarish. And should they even succeed in doing so, they claimed they could end up imperiling the owl, of which scientists knew of only six or seven individuals.

And ironically enough, conservation may be making it more difficult to collect specimens. To fight the growing scourge of the illegal wildlife trade, some laws forbid the gathering of species, whether you’re a scientist or a poacher. In that case, if you’re lucky, a photo will be all you can take home. I mean, it couldn't hurt.

Well, other than maybe starting a taxonomic war.

1UPDATE 12/16/16 7:55 PM ET: A previous version of this story mischaracterized Gutiérrez’s response to Mah; the error has been corrected.