Category Archives: Extinction

Friday Fellow: Emerald Ash Borer

by Piter Kehoma Boll

It’s time for our next beetle and this time our fellow is a species that spent its first century after discovery without calling much attention but then something happened. Its name is Agrilus planipennis and is commonly known as the emerald ash borer.

An adult emerald ash borer in Virginia, USA. Photo by Bryan Wright.*

Native from East Asia, the emerald ash borer is found in southeastern Russia, Mongolia, northern China, Korea and Japan. Adults measure about 8.5 mm in length and have a metalic green color on the head, pronotum and elythra, and an iridescent-purple metalic color on the dorsal side of the abdomen, seen when the wings are open. They live in the canopy of ash trees (Fraxinus spp.) during spring and summer and feed on their leaves.

After about a week as adults, the emerald ash borers start to mate. Females remain on the trees and males hover around looking for them. Once a female is located, the male drops over her and they start to mate. After mating is concluded, females live for some more weeks and typically lay about 40 to 70 eggs, although some live longer and may lay up to 200 eggs.

Dorsal view of an emerald ash borer with open wings showing the iridescent-purple abdomen.

The eggs are laid between crevices or cracks of the bark and hatch about two weeks later. The newly hatched larvae chew through the bark, reach the inner tissues of the trunk and start to feed on them. They reach up to 32 mm in length in the fourth instar, more than three times the length of the adult, and pupate during spring, emerging as adults soon after. In China, adults emerge from the trees in May.

A larva inside an ash tree in Pennsylvania, USA. Credits to the Pennsylvania Department of Conservation and Natural Resource.**

In its native area, the emerald ash borer can be a nuisance but is not highly problematic to ash trees because it occurs in low densities. However, in 2002, the species was found in the United States feeding on local ash species. Since the emerald ash borer has no natural predators in North America and the ash species in this continent did not evolve to be resistant to infection, it started to spread very quickly. In less than two decades, the beetle has killed millions of ash trees and is a serious threat to the more than eight billion ash trees found in North America. With the death of ash trees, North American forests become vulnerable to more invasive species, which will only worsen the scenario.

Damage caused by the larvae to a tree in New York state, USA. Photo by iNaturalist user bkmertz.*

In order to control the spread of the emerald ash borer, ash trees are treated with pesticides. Four parasitoid wasps from China known to attack only the emerald ash borer have also been released in North America to help control the spread and their success is still being assessed. Traps, such as glue-covered purple panels, which are visually attractive to the beetles, are also used to capture the animals and determine the extent of the invasion.

Once more, a completely fine species has led to an ecological disaster due to human influence and now we are running to find ways to avoid an ecosystem collapse throughout an entire continent.

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References:

Francese JA, Mastro VC, Oliver JB, Lance DR, Youssef N, Lavallee SG (2005) Evaluation of colors for trapping Agrilus planipennis (Coleoptera: Buprestidae). Journal of Entomological Science 40(1): 93-95.

Liu H, Bauer LS, Miller DL, Zhao T, Gao R, Song L, Luan Q, Jin R, Gao C (2007) Seasonal abundance of Agrilus planipennis (Coleoptera: Buprestidae) and its natural enemies Oobius agrili (Hymenoptera: Encyrtidae) and Tetrastichus planipennisi (Hymenoptera: Eulophidae) in China. Biological Control 42(1): 61-71. doi: 10.1016/j.biocontrol.2007.03.011

Wang XY, Yang ZQ, Gould JR, Zhang YN, Liu GJ, Liu ES (2010) The biology and ecology of the emerald ash borer, Agrilus planipennis, in China. Journal of Insect Science 10(1): 128. doi: 10.1673/031.010.12801

Wikipedia. Emerald ash borer. Available at < https://en.wikipedia.org/wiki/Emerald_ash_borer >. Access on 9 December 2019.

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Should we save or should we get rid of parasites?

by Piter Kehoma Boll

Parasites are special types of organisms that live on or inside other lifeforms, slowly feeding on them but usually not killing them, just reducing their fitness to some degree. This is a much more discrete way to survive than killing or biting entire parts off, as predators (both carnivores and herbivores) do. However, different from these creatures, parasites are often regarded as unpleasant and disgusting. Yet parasitism is the most common way to get food in nature.

When I introduced the rhinoceros tick in a recent Friday Fellow, I mentioned the dilemma caused by it. Since the rhinoceros tick is a parasite of rhinoceroses, and rhinoceroses are threatened with extinction, a common practice to improve the reproductive fitness of rhinos is removing their ticks, but this may end up leading the rhinoceros tick to extinction.

This actually happened already with other parasites, such as the louse Coleocephalum californici, which was an exclusive parasite of the California condor Gymnogyps californianus. In order to save the condor, a common practice among veterinarians working with conservationists was to delouse the birds and, as a result, this louse is now extinct. The harm that the louse caused to the condor was so little, though, that its extinction was not at all necessary, being nothing more than a case of negligence and lack of empathy for a small and non-charismatic species.

The California condor louse Coleocephalum californici was extinct during a poorly managed campaign to save the California condor Gymnogyps californianus. Image extracted from https://www.hcn.org/blogs/goat/the-power-and-plight-of-the-parasite

The louse Rallicola (Aptericola) pilgrimi has also vanished forever during the conservation campaigns to save its host, the little spotted kiwi, Apteryx owenii, in another failed work.

The efforts to save the little spotted kiwi, Apteryx owenii, from extinction led to the extinction of its louse. Photo by Judi Lapsley Miller.*
The now extinct Rallicola (Aptericola) pilgrimi. Credits to the Museum of New Zealand.***

Another group of parasites that is facing extinction are fleas. The species Xenopsylla nesiotes was endemic to the Christmas Island together with its host, the Christmas Island rat, Rattus macleari. The introduction of the black rat, Rattus rattus, in the island led to a quick decline in the population of the Christmas Island rat, which went extinct at the beginning of the 20th century and, of course, the flea went extinct with it. The flea Acanthopsylla saphes has likely become extinct as well. It was a parasite of the eastern quoll, Dasyurus viverrinus, in mainland Australia. The eastern quoll today is only found in Tasmania, as the mainland Australia’s population went extinct in the mid-20th century. However, the flea was never found in the Tasmanian populations, so it is likely that it died away in mainland Australia together with the local population of its host.

The Manx shearwater flea Ceratophyllus (Emmareus) fionnus. Photo by Olha Schedrina, Natural History Museum.*

But things have been changing lately and fortunately the view on parasites is improving. A recent assessment was made on the population of another flea, the Manx shearwater flea, Ceratophyllus (Emmareus) fionnus. This flea is host-specific, being found only on the Manx shearwater Puffinus puffinus. Although the Manx shearwater is not at all a threatened species and has many colonies along the North Atlantic coast, the flea is endemic to the Isle of Rùm, a small island off the west coast of Scotland. Due to the small population of its host in this island, the flea has ben evaluated as vulnerable. If the Manx shearwater population in the Island were stable, things would be fine but, as you may have guessed already, things are not fine. Just like it happened in Christmas Island, the black rat was also introduced in the Isle of Rúm and has become a predator of the Manx shearwater, attacking its nests.

The Manx shearwater, Puffinus puffinus, is the sole host of the Manx shearwater flea. Photo by Martin Reith.**

Some ideas have been suggested to protect the flea from extinction. One of them is to eradicate the black rat from the Isle or at least manage its population near the Manx shearwater colonies. Another proposal is to translocate some fleas to another island to create additional populations in other Manx shearwater colonies.

But why bother protecting parasites? Well, there are plenty of reasons. First, they comprise a huge part of the planet’s biodiversity and their loss would have a strong impact on any ecosystem. Second, they are an essential part of their host’s evolutionary history and are, therefore, promoters of diversity by natural selection. Removing the parasites from a host would eventually decrease its genetic variability and let it more vulnerable to other new parasites. Due to their coevolution with the host, parasites are also a valuable source of knowledge about the host’s ecology and evolutionary history, helping us know their population dynamics. We can even find ways to deal with our own parasites by studying the parasites of other species, and parasites are certainly something that humans managed to collect in large numbers while spreading across the globe.

Parasites may be annoying but they are necessary. They may seem to weaken their host at first but, in the long run, what doesn’t kill you makes you stronger.

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References:

Kirst ML (2012) The power and plight of the parasite. High Country News. Available at < https://www.hcn.org/blogs/goat/the-power-and-plight-of-the-parasite >. Access on 3 November 2019.

Kwak ML (2018) Australia’s vanishing fleas (Insecta: Siphonaptera): a case study in methods for the assessment and conservation of threatened flea species. Journal of Insect Conservation 22(3–4): 545–550. doi: 10.1007/s10841-018-0083-7

Kwak ML, Heath ACG, Palma RL (2019) Saving the Manx Shearwater Flea Ceratophyllus (Emmareus) fionnus (Insecta: Siphonaptera): The Road to Developing a Recovery Plan for a Threatened Ectoparasite. Acta Parasitologica. doi: 10.2478/s11686-019-00119-8

Rózsa L, Vas Z (2015) Co-extinct and critically co-endangered species of parasitic lice, and conservation-induced extinction: should lice be reintroduced to their hosts? Oryx 49(1): 107–110. doi: 10.1017/S0030605313000628

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Filed under Conservation, Ecology, Evolution, Extinction, Parasites

Daytrippers’ chips are killing species in protected areas

by Piter Kehoma Boll

Leia em português

There’s nothing as threatening to nature as humans, as we all know. A lot of species have become endangered and even extinct due to human influence all around the world. As an attempt to protect whatever is left, we have been creating protected areas where species should be able to live their lives without the dangers of humanity.

However, in order to raise awareness about the importance of preserving the biodiversity, most protected areas accept human visitors. Although it does have some effect to improve the visitors’ view about nature and its importance, there are a lot of undesired side effects. Humans walking through a forest cause noise that disturbs the local fauna and the soil compaction caused by walking can lead to changes in vegetation growth and soil drainage.

But another human behavior that appears to have serious consequences on biodiversity conservation is our tendency to carry food with us, such as snacks, and eat it anywhere. People visiting a protected area may eat something on the way through the woods or stop for a picnic. Many species love food remains left by humans and will thrive with them.

Two Steller’s jays in Big Basin Redwoods State Park. Photo by iNaturalist user kgerner.*

One species that benefits from human food is the Steller’s jay, Cyanocitta stelleri, a corvid that is common across the the west coast of North America. As a result, this species is not at all threatened at the moment and it tends even to follow humans because of the easy access to food. In the wild, this species is a generalist omnivore, feeding on seeds, fruits, invertebrates, eggs and small vertebrates, such as rodents and bird nestlings.

Another bird that can be found in the same areas as the Steller’s jay is the marbled murrelet Brachyramphus marmoratus, a small seabird. Different from most seabirds, the marbled murrelet does not nest in cliffs or burrows near the water but on branches of old-growth conifers. As a result, they may move up to 80 km inland to find a suitable place to nest. Different from the Steller’s jay, the marbled murrelet does not benefit from human snacks. On the contrary, they may be its ruin.

A young marbled murrelet found in the Big Basin Redwoods State Park. Photo by iNaturalist user basinbird.*

The marbled murrelet relies heavily on old forests to reproduce and the female lays only one egg per year, leading to a low reproductive rate. Due to the removal of old forests by humans, the marbled murrelet has lost a lot of its original habitat and is currently considered an endangered species.

One of the few remaining areas for this species to nest is located in the Big Basin Redwoods State Park in California. The park contains many options for camping, which means humans bringing food all the time. This attracts a lot of Steller’s jays, which feast on the crumbs and other remains, and reproduce explosively. When humans are not present, this increased population migrates toward new areas, sometimes following humans to the cities, or starts to feed on whatever is present in the park, and one of the most nutritious options are nestlings of the marbled murrelet.

With an already endagered population, the marbled murrelet is about to get extinct because our desire to walk through the woods is accidentally increasing the population of one of its main predators. Will we ever be able to have a good impact on this planet?

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Reference:

West EH, Brunk K, Peery MZ (2019) When protected areas produce source populations of overabundant species. Biological Conservation 238: 108220. doi: 10.1016/j.biocon.2019.108220

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*Creative Commons License This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

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Filed under Conservation, Extinction, Ornithology

Green turtles mistake plastic debris for dead squids, eat them, and die

by Piter Kehoma Boll

Plastic pollution is a popular topic recently and it is not rare to find pictures of animals that died due to plastic ingestion or other complications, such as asphyxia, caused by plastic pieces. However, the cause of plastic ingestion by most species is yet unknown.

Albatross with its stomach filled with plastic pieces.

The leatherback turtle, Dermochelys coriacea, is often mentioned as a species that suffers from plastic ingestion due to its diet composed primarily by jellyfish, which floating plastic bags can be mistaken for. However, another widespread sea turtle, the green turtle, Chelonia mydas, is also a common victim of plastic ingestion and amounts as small as 1 g are enough to kill juvenile specimens by blocking their guts. The diet of juvenile and adult green turtles is composed mainly by seagrass and algae, so the ingestion of plastic must be the result of another cause and not its similarity to jellyfish.

A decaying plastic bag in the ocean looks like a jellyfish. Photo by Wikimedia user Seegraswiese.*

Despite being almost strictly herbivorous, green turtles ingest animal matter when they are very young and can eventually consume animals as adults too, probably as a strategy to survive when their main food source is scarce. The ingestion of animal matter is usually done by scavenging, and a common scavenged item in their diet are dead squids.

A green turtle surrounded by seagrass, its main food source. Photo by Wikimedia user Danjgi.**

A recent study has investigated the relationship between scavenging behavior and plastic consumption in the green turtle and found out that the amount of plastic ingested by individuals feeding on dead squids is much higher than that ingested by individuals that do not present a scavenging behavior. In Brazil, plastic ingestion accounts for about 10% of the deaths of green turtles but this number may be as high as 67% among green turtles that feed on squid carcasses.

The ingestion of dead animals used to be an efficient way for green turtles to gain high amounts of protein. However, the fact that, currently, most floating material in the ocean is plastic and not dead animals turned a successful strategy into a deadly trap. If humans do not start controlling plastic waste production there will be only two possible outcomes for the green turtles in face of this new selective pressure: adaptation or extinction.

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References:

Andrades R, Santos RA, Martins AS, Teles D, Santos RG (2019) Scavenging as a pathway for plastic ingestion by marine animals. Environmental Pollution 248: 159–165. doi: 10.1016/j.envpol.2019.02.010

Mrosovsky N, Ryan GD, James MC (2009) Leatherback turtles: the menace of plastic. Marine Pollution Bulletin 58(2): 287–289. doi: 10.1016/j.marpolbul.2008.10.018

Santos RG, Andrades R, Boldrini MA, Martins AS (2015) Debris ingestion by juvenile marine turtles: an underestimated problem. Marine Pollution Bulletin 93(1–2): 37–43. doi: 10.1016/j.marpolbul.2015.02.022

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Filed under Behavior, Conservation, Extinction, Pollution, Zoology

Think of the worms, not only of the whales, or: how a planarian saved an ecosystem

by Piter Kehoma Boll

Leia em português

Due to the massive interference of human practices on natural habitats during the past decades, ecosystem restoration has become a trend in order to try to save what is still savable. Unfortunately, the effort of ecologists and other experts alone is not enough to achieve that, and a larger section of the society needs to be engaged in helping reach the goals. In order to do so, it is common to appeal to the beauty and cuteness of endangered species, which usually include mammals and birds, since they are more likely to caught the public’s attention. However, most of the endangered species are invertebrates or other less charismatic beings, and they are often ignored even by biologists.

Hopefully, things are able to change on this matter. Recently the first ecosystem restoration directed to save an invertebrate was successful, and I am here to tell you about it.

The invertebrate in question is a freshwater planarian named Dendrocoelum italicum. It was discovered in 1936 in a cave in northern Italy named Bus del Budrio. Inside the cave, there was a small freshwater pool, about 5 × 5 m or little more, caused by a waterfall from a small stream coming through a narrow elevated corridor. The species is apparently found only in this pool and nowhere else.

There are no available photos of Dendrocoelum italicum, but it should look similar to the widespread Dendrocoelum lacteum seen here, but D. italicum lacks the eyes. Photo by Eduard Solà.*

During the 1980’s, a pipe was installed to divert the water from the stream to a nearby farm. The waterfall ceased to exist and the pool dried up permanently. The planarian survived in a very narrow rivulet that formed inside the cave and some small isolated ponds resulting from water drips. This critical condition of the population was discovered in 2016 by a research group from the University of Milan. They informed the administrators of the cave about the situation and, together, the team started to raise awareness about the situation of the cave among the citizens that benefitted from the reservoir formed by the diverted water, which made the farmer responsible for diverting the water agree to remove the artificial structure.

Image of the inside of the cave. Photo by Livio Mola. Extracted from https://www.naturamediterraneo.com/forum/topic.asp?TOPIC_ID=57050

The removal happened on December 3, 2016 after all the planarians occurring in the rivulet were collected and stored in plastic tanks inside the cave. When the waterfall was restored, it quickly started to fill the old pool again and, one day later, the planarians were released into the pool.

The ecosystem was monitored during the following two years until January 2018. The number of planarians varied greatly during the survey, but was not significantly larger after the restoration from what it was before. However, there was a significant increase in the population of a bivalve species, Pisidium personatum, and a small increase in the population of a crustaceon of the genus Niphargus. Additionally, annelids of the family Haplotaxidae, that were absent in the cave, appeared after restoration. Thus, it is clear that the ecosystem benefited from the reappearance of the pool.

Thanks to the efforts of those researchers, Dendrocoelum italicum now has a better chance to avoid extinction. However, this is not an isolated case. There are many cave-dwelling planarian species all around the world living under similar conditions, usually restricted to a single small pool inside a single cave. Many of those occur, or occurred, as D. italicum, in Italy, but the help came to late for some of them. For example, a closely related species, Dendrocoelum beauchampi, was discovered in 1950 in a cave in northwestern Italy named Grotta di Cavassola, but a recent survey found no planarians inside the cave, which seems to have suffered great alteration due to human activities. Similarly, the species Dendrocoelum benazzi was discovered in 1971 in central Italy in a cave named Grotta di Stiffe, but nowadays, with the cave open to turists and its water polluted, the planarians disappeared. It is very likely that both D. beauchampi and D. benazzi are now extinct. The situation is the same for other Italian species.

Out of Italy, a recently described species living a similar small environment is the Brazilian cave planarian Girardia multidiverticulata, which is known to occur in a small pool about 10 m² inside a cave named Buraco do Bicho in the Cerrado Biome.

Girardia multidiverticulata is a planarian species restricted a small 10 m² pool inside a cave in Brazilian cerrado. Credits to Souza et al. (2015)**

The case of Dendrocoelum italicum shows us it is possible to save small endemic populations of threatened habitats, but we need the help of the public. Let’s hope other ecosystems have a similar happy ending.

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References:

Manenti R, Barzaghi B, Lana E, Stocchino GA, Manconi R, & Lunghi E 2018. The stenoendemic cave-dwelling planarians (Platyhelminthes, Tricladida) of the Italian Alps and Apennines: conservation issues. Journal for Nature Conservation.

Manenti R, Barzaghi B, Tonni G, Ficetola GF, & Melotto A 2018. Even worms matter: cave habitat restoration for a planarian species increased environmental suitability but not abundance. Oryx: 1–6.

Souza ST, Morais ALN, Cordeiro LM, & Leal-Zanchet AM 2015. The first troglobitic species of freshwater flatworm of the suborder Continenticola (Platyhelminthes) from South America. Zookeys 470: 1–16.

Vialli PM 1937. Una nuova specie di Dendrocoelum delle Grotte Bresciane. Bollettino di zoologia 8: 179–187.

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Filed under Conservation, Extinction, flatworms, worms

An extinct frog that is still living

by Piter Kehoma Boll

Hybrids, as you probably know, are organisms that arise from the mating of two individuals of different species. A mule, for example, is a well known hybrid between a horse and a donkey. Hybrids are usually sterile, although not all of them are, and some of them have a very peculiar way to continue to exist by using a process called hybridogenesis.

Hybrids that rely on hybridogenesis function in the following way: there are two original species, let’s call them A and B. When they copulate with each other, they produce a hybrid offspring, AB, which has half of the genes from one parent and half from the other. In “normal” hybrids, such creatures are completely sterile, unable to produce viable gametes, or can give rise to a new hybrid species by producing mixed gametes. However, in this peculiar kind of hybrids, called kleptons, things work differently.

800px-rana_ridibunda_ii

Pelophylax kl. hispanicus, the holder of a treasure. Photo by Andreas Thomsen.*

When kleptons are producing gametes, they never recombine the genomes of the two parents, but rather exclude the genome of one of them and produce gametes that contain the genome of the other parent. For example, the hybrid AB produces only A gametes, while the B genome is excluded. This means that if AB mates with a partner of the species A, the offspring will be formed by pure A individuals. If mating with B, the offspring will contain only new AB hybrids.

hybridogenesis_in_water_frogs

The edible frog Pelophylax kl. esculentus is a klepton formed by breeding P. lessonae and P. ridibundus. The klepton only produces gametes of P. ridibundus, eliminating the genome of P. lessonae during meiosis. (Photo by Wikimedia user Darekk2).**

This mode of reproduction is very common in frogs of the genus Pelophylax, as the example seen in the picture above. Another interesting point about kleptons is that they are usually unable to mate with another klepton. They rely on one the parent species to reproduce, therefore “parasitizing” them.

A recently published paper on Pelophylax frogs reports a peculiar case in which one of the parent species is extinct. The klepton, known as Pelophylax kl. hispanicus, is the result of P. bergeri crossing with a now extinct species of Pelophylax. The case is that the gametes that P. kl. hispanicus produce are of the extinct species, but they can only fertilize gametes of P. bergeri. In other words, we could say that the extinct species is still alive inside the klepton, relying on P. bergeri to pass to the next generations.

41598_2017_12942_fig1_html

Pelophylax kl. hispanicus is a klepton that maintains the genome of an extinct species alive. Image extracted from Dubey & Dufresnes (2017).**

The authors suggest that perhaps we could find a way to bring the extinct species back, separated from P. bergeri. Although the result of crossing two P. kl. hispanicus is an sterile offspring, they think that continuous trials may end up revealing an eventual fertile offspring. Is it worth trying? Perhaps. But anyway, this is one more astonishing feature of nature, don’t you agree?

How many more extinct species may be living in a similar way, trapped in a hybrid?

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References:

Wikipedia. Hybridogenesis in water frogs. Available at <https://en.wikipedia.org/wiki/Hybridogenesis_in_water_frogs&gt;. Access on October 12, 2017.

Dubey, S.; Dufresnes, C. (2017) An extinct vertebrate preserved by its living hybridogenetic descendant. Scientific Reports 7: 12768. https://dx.doi.org/10.1038/s41598-017-12942-y

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Darwin’s Planaria elegans: hidden, extinct or misidentified?

by Piter Kehoma Boll

During his epic voyage on the Beagle, Charles Darwin visited Rio de Janeiro, Brazil, and collected some amazing land planarians, a group that until then was very little known. One of the species he found was Geoplana vaginuloides, the type-species of the genus Geoplana, at that time named Planaria vaginuloides.

f6387-vaginuloides-pedrabranca40

Geoplana vaginuloides (Darwin, 1844), the first Brazilian land planarian species to be described. Photo by Fernando Carbayo.*

The second species described by Darwin was named Planaria elegans. Darwin’s description is as it follows:

“Position of the orifices as in P. vaginuloides. Anterior part of the body little elongated. Ocelli absent on the anterior extremity, and only a few round the margin of the foot. Colours beautiful; back snow-white, with two approximate lines of reddish brown; near the sides with several very fine parallel lines of the same tint; foot white, exteriorly clouded, together with the margin of the body, with pale blackish purple: body crossed by three colourless rings, in the two posterior of which the orifices are situated. Length 1 inch; breadth more uniform, and greater in proportion to length of the body, than in last species.
Hab. Same as in P. vaginuloides. [Rio de Janeiro]”

And this is all we know about this species. Darwin did not provide any drawing and later researchers did not report this species again, except when mentioning Darwin’s publication. As you can see by the description, it is not very accurate. He does not say what is the breadth of each line or band, neither how many of the “several fine parallel lines of the same tint” there are. Here is a quick drawing I did of how I imagine the creature would be:

image description

My idea of what Darwin’s Planaria elegans may have looked like. Head to the left. Credits to myself, Piter Kehoma Boll.**

In 1938, Albert Riester described a land planarian from Barreira, a district in the city of Teresópolis, Rio de Janeiro, naming it Geoplana barreirana. He described it as it follows (translated from the original in German):

“Land planarian found on a leaf after a rain; greatest lenght ca. 20 mm. Middle of the back white with two fine purple-red (atropurpureus light) parallel stripes. Outside of the white also limitted by pale red, then follows (on both sides) a black band and laterally a black-brown marmorate pattern over brown background. The middle stripe ends at the rear [end]. Head spotted, marked with transversal spotted bands (regenerate?). Underside gray, bordered by black-brown. Anterior end is arched backwards.”

Fortunately, Riester provided a drawing, which you can see below:

Barreirana_barreirana_Riester

Geoplana barreirana drawn by Riester (1938).

They look a bit alike, right? Fortunately Geoplana barreirana (currently named Barreirana barreirana) was found by later researchers and we have photographs! See one specimen below:

f6284_barreiranatijuca3

A specimen of Barreirana barreirana found in the Tijuca National Park, Rio de Janeiro. Photo by Fernando Carbayo.*

Riester did not describe any transversal marks on his specimens, but he may have mistaken them for color loss in preserved specimens or something like that. Otherwise the specimen looks very similar to Riester’s drawing, and the internal anatomy, which Riester provided as well, is also compatible.

Now let’s try to fit Darwin’s description of Planaria elegans in this photograph. White background, two reddish brown stripes and several fine parallel stripes of the same tint. He likely described the animals from preserved specimens, even though he have seen them alive and collected them. Perhaps the colors had already faded a little and the black stripes, which internally touch two of the reddish stripes, may have been considered a single purple-red stripe? It is not clear, in his description, whether there is white between the “reddish brown” stripes and the “pale blackish-purple” sides, as I did in my drawing, or not, as in Barreirana barreiranabut certainly the dark gray sides of B. barreirana could be the same as the pale blackish purple sides of Planaria elegans, don’t you think? And B. barreirana HAS three white “rings” crossing the body. You can see the first and the second very clearly on the specimen above. The third one is not very well marked, but you can see a third white mark interrupting the gray sides. And the second and almost third marks seem to be quite where one would expect the two orifices (mouth and gonopore) of the planarian to be!

And what about the ventral side? Darwin described P. elegan‘s as being white with a pale blackish purple border as the sides of the dorsum. Riester described G. barreirana‘s as being gray bordered by black-brown. Here is Barreirana barreirana‘s ventral side:

Barreirana barreirana from below

Ventral side of Barreirana barreirana from the Tijuca National Park, Rio de Janeiro. Photo by Fernando Carbayo.*

It is white, or pale gray perhaps, and the borders are of the same color as the sides of the dorsum!

I think it is very, very likely that Darwin’s Planaria elegans and Riester’s Geoplana barreirana are the same species. The fact that no one but Darwin has ever seen a specimen of Planaria elegans makes it even more likely.

What do you think?

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See also:

How are little flatworms colored? A Geoplana vaginuloides analysis.

The fabulous taxonomic adventure of the genus Geoplana.

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References:

Darwin, C. (1844) Brief Description of several Terrestrial Planariae, and of some remarkable Marine Species, with an Account of their Habits. Annals and Magazine of Natural History 14, 241–251.

Riester, A. (1938) Beiträge zur Geoplaniden-Fauna Brasiliens. Abhandlungen der senkenbergischen naturforschenden Gesellschaft 441, 1–88.

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Filed under Cryptids, Extinction, taxonomy, worms, Zoology