As much as we push into the fringes and boundaries of out world, there are still mysteries that will always continue to elude us and be cloaked in the shadows. We have in modern times uncovered many new species, shedding light on the true biodiversity of our world, yet some of these newly discovered creatures pose as many questions as they answer. When a new species is classified, typically it is required that there be some sort of holotype, which is a single specimen that serves as evidence of and a physical illustration of a species for the purpose of officially describing it. In most cases, there are ample physical examples of a given species, but this is not always the case. For some particularly enigmatic animals there is a mere single, solitary individual upon which their entire kind is known to science. These are the creatures for which we have so little information that we are left to grasp and guess at just what they are. Here, we will explore the world of animals that have become known to science based on just one lone specimen, their habitats, behaviors, and life remaining an impenetrable mystery to us.
One species of mammal known from only a single specimen is the dusky flying fox (Pteropus brunneus), also known as the Percy Island flying fox. This species is known from a single individual collected in 1874 in the Percy Island group off Queensland, Australia, and no further examples have ever been found. Although only the one sole specimen exists, now mounted at the British Museum, reports from colonists of the islands in the 19th century suggest that the species was once rather plentiful on the islands, and it was widely sighted even after it was officially discovered, although no further specimens were provided.
The species has nevertheless remained a specter, with no further specimens ever found in its supposed habitat, and confounding all further attempts to locate it, leading for some scientists to suggest that the one collected specimen was perhaps a wayward individual originating from somewhere else, such as the Solomon Islands or the Louisiade Archipelago. It has also been speculated that the found specimen was perhaps merely an aberrant individual of a known species. Intriguingly, there were reports of a potential relic colony of the mysterious flying foxes sighted on Akens Island in the 1990s, but an investigation of the reports turned up no new specimens or even any sign of them. At present, the dusky flying fox is considered to be very likely extinct.
From the wilds of Ethiopia comes another enigmatic mammal known from a single lone specimen. The Ethiopian water mouse (Nilopegamys plumbeus), also known rather unappetizingly as the Ethiopian amphibious rat, is a highly water adapted rodent that is known from a single individual caught in a trap near the source of the Little Abbai River, at Gojjam, in north western Ethiopia in the 1920s. Further surveys of the area to locate and collect more of the species have failed to find any trace of them. Considering that the habitat where the type specimen was originally found had already been severely degraded by rapidly expanding pastureland for grazing cattle at the time, and is almost completely destroyed by such practices at present, the Ethiopian water mouse is most certainly gone forever, leaving us with only a single individual to truly decipher its natural history.
Some species of new mammal have been not only been identified from a single specimen, but also one that wasn’t even fully intact. One example is Sir David’s long-beaked echidna (Zaglossus attenboroughi), also known as Attenborough’s long-beaked echidna or the Cyclops long-beaked echidna, and named after none other than famous British naturalist Sir David Attenborough himself. The species is known from only a single specimen that was found in a badly damaged state in a remote area of New Guinea’s Cyclops Mountains in 1961 by Dutch explorers. This species is notable for being the smallest species of echidna.
There have been several attempts to locate more surviving specimens of Sir David’s long-beaked echidna since its discovery, most notably in 2007, when a team of researchers found promising evidence of the creatures in the form of distinct feeding holes and fresh tracks, but a thorough search of the area turned up no new specimens of the new echidna or even a sighting of one. Even so, local hunters of the area claim that the creature is around and often hunted, giving hope to conservationists that the species, although highly elusive, is perhaps not extinct, nor even as threatened as its current status would suggest. The one lone specimen of Sir David’s long-beaked echidna is mounted at the Leiden Natural History Museum in the Netherlands.
Recognized by even more tenuous physical evidence is the Somali Golden Mole (Calcochloris tytonis), a type of golden mole from the troubled African nation of Somalia. This particular species is known from only a single partial jawbone and some ear bones found in an owl pellet in 1964. Despite this very partial specimen, upon analysis the bones were deemed unique enough to classify it as a new species, although no further representatives of the species have ever been found. Interestingly, another species of golden mole, which in fact are only very distantly related to true moles, has also been classified based on one specimen as well. In 1950, an estate owner in Gouna, South Africa, found a single individual of a new type of golden mole that would go on to be called Visagie’s golden mole (Chrysochloris visagiei). There have been follow-up expeditions to the area to look for further specimens, but none have ever been found.
Also a species known from only a partial specimen is the small Samoan flying fox (Pteropus allenorum). The only known remains of this species were a broken skull and damaged skin collected in 1856 on the island of Upolu, Western Samoa, West Polynesia, by an H.C. Caldwell. These remains were then stored away at the Academy of Natural Sciences of Philadelphia until 2006, when they were accidentally found collecting dust in the basement and a researcher was astute enough to look into them further. Although found in 1856, it would not be until 2009 that it would be recognized as a new species, and is still only known from a poorly preserved skin and a partial skull. It is thought that this species is likely now extinct, as no further animals have ever been located despite extensive searches.
Birds and Reptiles
One of the most mysterious discoveries of a new bird species based on one specimen is that of the striking Liverpool pigeon (Caloenas maculate). The specimen was originally acquired by the 13th Earl of Derby, who added it to his vast collection of assorted birds and other animals, and here is where it long remained forgotten and lost amongst a myriad of other specimens at Knowsley Hall in Merseyside. The collection went to the Liverpool World Museum upon the Earl’s death in 1851 and the pigeon was discovered by pure chance, a mystifying lone specimen with no label or information attached to it as to when or where it was originally collected. The puzzling specimen, which is characterized by very small, practically useless wings and striking spotted green coloration, has been theorized as possibly having its origins somewhere in French Polynesia, which was popular with animal collectors at the time and some of the other animals in the Earl’s collection were from there. Other than that, the Liverpool pigeon remains a complete and total mystery.
Almost as mysterious as the tale of the Liverpool pigeon is that of a bird that was shot in 1825 by naturalist Andrew Bloxam while on an expedition to the island of Mauke, in the Cook Islands, which lie in the South Pacific northeast of New Zealand, between French Polynesia and American Samoa. The bird in question was a new type of starling, and its well preserved skin eventually wound up at the Natural History Museum in London, where it was discovered and found to be simply labelled “12.192,” with no other information as to when or where it had been gathered, leading to its nickname “the mysterious starling.” For years no one could figure out what this species was or where it came from, and it was often misidentified or mislabeled, further adding to the air of mystery and confusion surrounding it.
Mauke was not visited for serious investigation by ornithologists until 1973, and by that time the bird was apparently long extinct, likely due to the infestation of a very large variety of rats. This prevented the collection of any other new specimens of whatever the bird was, and further created an obstacle to positively identifying it. It was not until 1986 that its true origins were revealed by research and study of entries from Bloxam’s original diary and field notes done by the American ornithologist Storrs Olson, and it was finally truly recognized as a new species after over 150 years of obscurity. In a strange twist, it was also found that Bloxam had apparently shot some sort of unknown pigeon on the same trip to Mauke, and although this actual physical specimen was never found among the collections, it is speculated it may have been the only known example of the now extinct Mauke fruit dove.
Equally bizarre and enigmatic is the story of the bird species that is known tenuously through only a single wing. In 1990, researchers in Nechisar National Park, Ethiopia, discovered a dead, decomposing bird they could not identify by a roadside that they surmised had been killed by a passing car. The body of the bird was too badly decomposed to be of much use, so they removed one of its wings and sent it to the Natural History Museum in London, after which it was found to be a new species based on its unique coloration and came to be known as the Nechisar nightjar. It was an unusual way to identify a new species, a situation reflected even its scientific name, Caprimulgus solala, with the word “solala” meaning “only a wing.”
Although the species’ status is unknown, the Nechisar nightjar has been tentatively designated as “vulnerable” until more information is forthcoming. In the meantime, it has become a sort of Holy Grail for birdwatchers and ornithologists, who have traveled to the region in which the wing was found looking for further evidence of its owner’s existence. There have been a few reported sightings of a bird that could be the Nechisar nightjar, as well as a few blurry purported photos of it, but these have remained inconclusive and the species continues to be a phantom known from a mere single, solitary wing forgotten upon a remote roadside.
Reptiles are not exempt from single-holotype species either. In fact, the largest known species of gecko in the world is known from only one taxidermy specimen that is not even complete. The mounted specimen was first noticed in 1979 by herpetologist Alain Delcourt among a collection at the Marseille Museum of Natural History in France, and recognized as unique among geckos due to its coloration and impressive size. Efforts to identify the unusual creature were hampered by the fact that there was no information on where or when the specimen had been collected and no label, although it was surmised that it had probably been captured sometime between the years of 1833 and 1869 and likely had its origins somewhere in the Pacific. Other than that, the specimen long remained a perplexing enigma.
Researchers would later discover that the mounted gecko was similar in appearance to reports from New Zealand of a creature known locally as the kawekaweau, which was said to be a massive, rusty brown gecko with reddish stripes that was claimed to be around 62 centimeters (2 feet) long and “as thick as a man’s wrist.” There are some scattered accounts of early European explorers of New Zealand coming across mysterious large lizards which could have been the kawekaweau, and there is one record from 1870 of a Maori chief who saw a gecko that exactly matches the description of the museum specimen and killed it in the forests of the Waimana Valley, making it the only known detailed, documented sighting of one of the animals alive.
Based on this account and the similarities to the mounted gecko specimen, Delacourt and other respected researchers came to the conclusion that they were one and the same species. In 1986, the kawekaweau, now more formally known as Delacourt’s sticky-toed gecko or Delacourt’s giant gecko (Hoplodactylus delcourti), was named a new species solely based on this single mysterious museum mount. This large gecko can reach sizes of up to 2 feet long; nearly twice as large as the next largest gecko, the New Caledonian giant forest gecko, which can get up to 36 centimeters (14 inches) in length. Unfortunately, like many of the animals we’ve been investigating here, the Delacourt’s giant gecko is considered to be most likely extinct, and the species remain wrapped in mystery.
Considering the dark, impenetrable vastness of the Earth’s oceans, the sea is clearly an exciting frontier for new species discoveries, and here too we find examples of many enigmatic species known from only a single specimen. One of the most impressive is a new species of stingray called the New Ireland stingaree (Urolophus armatus), which is known from a single solitary juvenile specimen caught during an expedition in 1822 led by René Primevère Lesson and Prosper Garnot in the seas of the Bismarck Archipelago of New Ireland, in Papua New Guinea. The specimen was subsequently taken to a museum in Paris, where it was stored away until finally being officially described as a new species in 1841, with some researchers arguing that it could possibly even be a new genus. This one lone specimen remains the only example of the New Ireland stingaree, and no further individuals have ever been caught or even seen.
The New Ireland stingaree is rather unusual among others in its family in that it displays rows of denticles and spinules, or tiny sharp dermal thorns, along its back and the base of its tail as a defense mechanism against predators. Indeed, this feature is reflected in the stingaree’s latin name, with “armatus” meaning “armed.” Almost nothing is known about the New Ireland stingaree, as there was no record of the exact conditions under which it had been caught, and it is not even known just what its natural range, depth and habitat might be, or if it is extinct or not. Although museums and scientists have requested that any further individuals that are caught be donated for analysis, none have been forthcoming, and indeed the area where the original specimen was caught is one of the least surveyed areas of ocean on earth.
Equally enigmatic is the slender worm-eel (Leptenchelys vermiformis), an unusual looking, light yellow, worm-like fish which is known from one 12cm-long specimen dredged up from a mud bottom in 20 meters of water near Costa Rica. There is virtually nothing known about this species, and no new specimens have been caught. Another odd looking fish based on one specimen is the Walker’s toadfish (Batrachoides walker), which was discovered in 1953, when a single individual measuring 21 cm long was caught in the Gulf of Panama. The area where Walker’s toadfish was caught has been extensively scoured for further examples, yet none have been caught and it is feared to be extinct.
There are larger species of fish known from a sole individual as well. The Somali grouper (Epinephelus indistinctus), which measures around 80 cm long (nearly 3 feet) long, was described from a lone specimen collected in 1991 off the Puntland coast of Somalia at a depth of 70 to 200 meters. Even though there has only been one specimen ever examined, fishermen of the area claim that the species is often caught by trawl and hand lines, although it is not specifically targeted. The Somali grouper is not considered to be extinct, and may even be common for all we know, but the difficulty in sending expeditions to the war torn, pirate plagued area have held back any further assessment and study of the unique species.
Some of the most mysterious rare new species are also the smallest, and the insect world has its share of data deficient species as well. Perhaps the most well-known, as well as gruesome, example is the colorfully named Lady Gaga braconid, the sole specimen of which was collected in Chae Son National Park in Thailand during a wildlife survey in 2012. The tiny insect, which measures just 5mm (.1 in) long, is a type of parasitic wasp that is thought to lay eggs in a host’s head, after which the larva hatch and feed, eventually grotesquely burrowing their way out. The insect reached mainstream news headlines due to its unique and extravagent name, although why exactly it was called the Lady Gaga braconid is anyone’s guess.
Another exciting insect discovery from the same year was an eerily beautiful bioluminescent type of giant cockroach called Luchihormetica Luckae, the sole known specimen of which was collected at the Tungurahua Volcano in Ecuador. The bug was first described in 2012, but all research on this enigmatic insect was done on a single preserved specimen gathered in 1939. While the moniker of cockroach may instill unease in some, Luchihormetica Luckae is actually a strikingly attractive insect that is a rare case of a terrestrial creature that displays a form of bioluminescence; with two spots on its carapace that glow. It is thought that the bioluminescence in this case is for the purpose of mimicking a toxic beetle that is native to the same habitat for the purpose of tricking predators, making it the only known example on earth of bioluminescence used for mimicry in a land animal. It is also the first known instance in the world of asymmetrical bioluminescence. Unfortunately, this endearing insect, whose luminescent pattern has often been likened in appearance to the Jawas from the movie Star Wars, may already be extinct due to a major eruption of the Tungurahua Volcano in 2010. There have been no other individuals of this bizarre species collected since the one known specimen in 1939.
One of the smallest and rarest insects in the world is a species known from only one specimen. The new species of ladybug was found crawling across a sand dune in the U.S. state of Montana, along the north shore of Red Rocks Lake, by then entomology graduate student Ross Winton, from Montana State University in 2009. The insect is so miniscule, only 1mm long, that Winton at first thought it was merely a body part from an ant. Closer inspection led him to think that the ladybug had no head, as the species has the unique and bizarre ability to pull its head down into its thorax when threatened, much like a turtle retreating into its shell. It was also unusual for a lady bug in that it was tan in color and had no spots.
When the odd insect was sent off to an Australian entomologist in Canberra to be analyzed, it was found to be a type of ladybird beetle for which only one other known specimen had ever been collected. Before anyone denounces this as breaking the “only a single specimen” theme of this article, it must be noted that in order for a new species of ladybird beetle to be officially classified, the rules dictate that a male of the species is required. The previous specimen was a female captured in the Centennial Valley in Idaho, making Winton’s finding the only known male specimen and therefore the one on which the designation as a new species can be finally based. In fact, the new species, which has come to be called Allenius iviei, is so bizarre and unique that it actually represents an entire new genus.
If all of these species based on a single specimen aren’t impressive enough already, then how about one based on only a photo of a single specimen? In the only example of a new insect species named purely on a photograph, a new type of fly was recently discovered in 2015 when the photo, which was taken in Africa, was considered for a new book on flies in Africa, and researcher Neal Evenhuis, from the Bishop Museum, Hawaii, recognized it as a unique new species and perhaps even a distinct new genus. The fly, with its large and strangely shaped body and distinct black and yellow coloration, was something Evenhuis had never seen before. It was later determined to be a new species of the extremely rare genus of fly from southern Africa called Marleyimyia, which was previously only represented by two species and a total of three specimens. The fly in the picture was recognized as distinct, and given the name Marleyimyia xylocopae, although no specimen living or dead has ever been collected and it has only ever been seen in the photograph, which was taken by entomologist Drs. Stephen A. Marshall, from the University of Guelph, Canada.
The naming of this species based on a photograph alone has caused quite a bit of controversy within the scientific community, as typically a physical holotype is required to do so. Marshall and Evenhuis have defended their actions by pointing out that there should be an alternative to the traditional method considering the difficulty of getting permits to some areas and carrying out expeditions to collect and preserve specimens in remote areas. The naming of this fly as a species without a physical specimen has opened a debate on just what sort of evidence should be allowed before an animal can be officially able to be classified as a whole new species. It also opens up a whole grey area as to what evidence constitutes grounds for a new animal to be recognized as a new species, generating interest among cryptozoologists who would love to see such evidence validated. For now, photographic evidence alone is a tenuous and risky foundation upon which to make such a distinction at best, even with a very clear photo.
It is clear that this world of ours still hides quite a few new species from our ongoing efforts to categorize the living things of this planet. While we may manage to uncover a great many, it seems that there will always be those which taunt us by only divulging a single sample, or even just a photo as the case may be, on which to base our entire knowledge of the species. Where are they? What are their habits, habitats, distribution, or defining attributes? Are they extinct or merely just hiding from us? For some species perhaps the answers to all of these mysteries may forever elude us, locked away within a single, mysterious specimen that sits cold and still upon its mount; an enigmatic specter projecting intrigue with its dead stare and keeping its secrets close.