Pyrite Disease: Keeping Fool’s Gold Challenges Museums

Pyrite, or fool’s gold, has duped prospectors for millennia, and now it’s providing a tricky challenge for museums.

Pyrite is a very common mineral found worldwide and in a very large variety of rocks. The Canadian Museum of Nature collection holds about 800 pyrite specimens. Each specimen has the identical chemical formula — iron disulfide, FeS2. But slight differences in the conditions in which a pyrite specimen formed gives each a unique shape, with cubes being the most common.

A pyrite specimen in a specimen box on a cabinet shelf.

An excellent pyrite specimen with a bright gold colour and cubic shapes. Catalogue number: CMNMC 43372. Image: Christian Capehart © Canadian Museum of Nature.

With its shiny yellow colour and metallic shine, pyrite closely resembles gold. Even more confusingly, it also commonly occurs with gold deposits. Many prospectors have thought they struck it rich when they actually just found a lode of pyrite, hence its common name.

Now, museum staff are dealing with another of the mineral’s challenging characteristics: pyrite can rust.

When exposed to humid air, pyrite reacts with oxygen and water to create iron sulfide (the rust), corrosive sulfuric acid and harmful sulfur dioxide gas. This chemical reaction, called pyrite disease, causes specimens to crack and crumble. Left unchecked, pyrite disease eventually destroys a specimen.

Moreover, the corrosive acid and gas can destroy the storage containers holding the pyrite and even damage surrounding minerals. This is why it’s called pyrite disease, because it acts like a contagious infection that can spread. The acid and gas are also a health hazard for museum staff.

A pyrite specimen that is cracked and discoloured.

A specimen of pyrite damaged by pyrite disease, resulting in cracks and discolouration. Image: Christian Capehart © Canadian Museum of Nature.

Since the museum holds pyrite specimens that are of great scientific interest and stunning beauty, it is of the utmost importance that we take proactive steps to preserve them.

Pyrite oxidation is triggered by humid air, so the best ways we have found to prevent pyrite disease are to lower the humidity of the collection room and keep the specimens in dry, impermeable containers.

With these steps, the museum’s pyrite specimens have the potential to keep fooling the unwary for millennia.

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Triceratops skull delivers a Wow! of a Christmas gift

Removing dinosaur bone from rock is much like opening a Christmas gift: you never know what to expect. Sometimes, if you are really lucky, what’s revealed makes you take a step back and say, Wow!

And that’s exactly the early holiday surprise I got several weeks ago working on the museum’s one-of-a-kind Triceratops skull. It might contain the world’s first fossil evidence of this horned-dinosaur’s skin from the area of the neck frill.

When I last wrote about the partial skull of a large Triceratops prorsus in our collections, I had just started preparation work on the specimen. From reading Charles M. Sternberg’s 1929 original field notes, our expectations were already high. The complete frill and both horn cores he collected and preserved in two plaster jackets could be the world’s largest Triceratops.

Drawing of a horned dinosaur skull

Drawing of a Triceratops prorsus skull collected by the pioneering American palaeontologist Othniel Charles Marsh. The first fossils of this famous horned dinosaur were found in the late 19th century in Colorado, and have since been collected from Wyoming, South Dakota, Alberta and Saskatchewan. © Biodiversity Heritage Library (CC BY-SA 2.0)

Now, after five months of meticulous work on the backside of the bony frill, a completely unexpected find has emerged that could change our view of what Triceratops looked like.

A major challenge in preparing this Triceratops specimen is that much of the skull is fractured, and between these thin gaps in the fossil, tiny fragments and rock dust have accumulated. Before the fractures can be repaired, this accumulation must be removed.

Photograph of fossil in a partial plaster jacket.

A section of the bony shield that flared out around the neck of our Triceratops specimen, seen here sitting in a plaster jacket in the museum’s palaeontology workshop. The surface has been partially cleaned revealing many fractures. When C. M. Sternberg examined this fossil soon after its discovery in 1929, he made note of its exceptionally large size. Catalogue number: CMNFV 56508. Image: Alan McDonald, © Canadian Museum of Nature.

Close-up view of fractures in fossil of a horned dinosaur.

View of the frill section from above following complete exposure and cleaning of the numerous fractures that riddle the surface. One such fracture held a fragment containing a very interesting surprise — what appears to be preserved skin. Catalogue number: CMNFV 56508. Image: Alan McDonald, © Canadian Museum of Nature.

One afternoon in early October, as I was removing and sifting through the dust trapped in the fractures, I noticed a small, broken section of fossil.

A triangular-shaped piece of fossilized bone had separated from the main frill, but remained largely in place.  As I cleared the rock fragments and lifted out this small bit of fossil bone, what I saw underneath it made me quickly set down my brush.

To my surprise, there was a small section of what looks to be beautifully fossilized dinosaur skin.

Canals in the surface of a dinosaur fossil.

This block of sediment covered a portion of the Triceratops frill and bears the impression of its surface features, including deep channels and pits. These may have once harboured blood vessels and other soft-tissue structures. One theory concerning the frills of horned dinosaurs is that they were covered in a hard sheath, perhaps composed of keratin, just like our fingernails. It’s possible that this protective covering was so dense and tight against the skull that the blood vessels providing oxygen and nutrients normally found in the soft tissue instead grew into the outer layers of the bone of the skull. Catalogue number: CMNFV 56508. Image: Alan McDonald, © Canadian Museum of Nature.

If so, it is the first evidence of skin from the head of this dinosaur species. Since it was first discovered in 1887, there has been no fossil material found to give any clear indication of what covered this horned dinosaur’s iconic frill. For more than a century, it was assumed that a mosaic of scales covered the surface of the frill, but others have more recently suggested that it was instead covered by a tough, horny sheath. Until now, we had no way to be sure.

Fossil skin impression.

The polygonal features seen in this photo appear to be the remains of fossilized skin preserved in association with the frill. The fossil has been removed for further study to confirm this initial identification. Once preparation of the top side of the frill is underway, it may finally provide some answers regarding the nature of the skin on a horned dinosaur’s neck shield, and perhaps also earn the specimen the title of the largest Triceratops skull ever described. Catalogue number: CMNFV 56508. Image: Alan McDonald, © Canadian Museum of Nature.

Taking a closer look at the section of distinctly patterned features with Dr. Jordan Mallon, the Canadian Museum of Nature’s dinosaur specialist, we decided we needed to re-examine how best to approach preparing the opposite side of the frill. We want to not only preserve any delicate fossilized skin it may retain, but if possible, also keep it from separating from the bone.

With this in mind, I am proceeding even more carefully and slowly in continuing the finer preparation and stabilization of the currently exposed side of the frill. Over the next few weeks, we will create a new plaster jacket to support the specimen, flip it over, and then see what new surprises the other side might have for us.

For now, though, I am quite content to enjoy this early, unique Christmas gift of probable fossilized Triceratops skin!

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Cruising the Globe Undetected

A man wearing waders standing in a tide pool examines the contents of his dip net

Emeritus museum scientist Ed Bousfield (now deceased) found that Jassa marmorata’s native range in Atlantic North America was on wave-exposed, natural shores, far from harbours and other human-built structures. Image: Kathleen Conlan, © Canadian Museum of Nature

The little shrimp-like animal Jassa marmorata was never thought to be a hitchhiker until museum collections told us otherwise. Now we’re finding out that it has been using humans to cruise the globe for centuries.

Each individual Jassa lives in the ocean in a self-built tube which it glues to its neighbour’s tube. When thousands get together, they amass a gooey colony that fouls anything solid. As a result, Jassa is infamous for blocking water pipes, clogging aquaculture nets and coating oil rigs.

This ability to stick and hold has also made this little marine creature a global hitchhiker.

Two shrimp-like creatures each with a pair of enlarged claw-like appendages on the left. One shrimp-like creature in her tube on the right.

Two Jassa marmorata males on the left. Their large front claws are a signalling device. A Jassa marmorata female in her homemade tube on the right. Image: Kathleen Conlan, © Canadian Museum of Nature.

Early explorers started it. The hulls of wooden ships were ideal for Jassa to stick and go.

The collections of the Natural History Museum in London, England reveal that the H.M.S. Challenger was likely distributing Jassa marmorata from Europe to the Southern Hemisphere as it travelled around the world from 1872 to 1876. Jassa marmorata was found swimming beside the ship in the deep ocean off of South Africa and again near Chile, far from its natural rocky shore habitat. Probably it was living on the ship’s hull and periodically falling off, duping the naturalists aboard ship into thinking that it was a local.

Through decades of dispersion—including from oyster imports and emptied ballast water—the North Atlantic native, Jassa marmorata is now fouling harbours in South America, Asia, Russia, Australia, New Zealand, Africa, the Middle East, and most of Europe. Historical collections show that it has been fouling some of these harbours since the 1800’s, though ship commerce may have been distributing it much earlier.

A Victorian illustration of a large sailing ship

As it circumnavigated the globe from 1872 to 1876, the H.M.S. Challenger unwittingly gave a North Atlantic native, Jassa marmorata, a round-the-world tour. Image: William Abbott Herdman, Public domain. Source: Wikipedia Commons

Unwitting scientists may still be giving Jassa a lift to new habitats.

A recent deep-sea expedition sampled the seabed from Europe to the North Pole. In collected samples, it found Jassa marmorata all the way there and back while no other species was so consistently found. Jassa marmorata has never been found in mud, or deeper than about 30 meters, and never in the Arctic.

Was it really living in mud at 4000 meters under the sea ice at the North Pole? Not likely.

I bet this world-class hitchhiker was living in the ship’s seawater system. Every time the hoses were used to sieve the mud from samples, a few Jassa were dislodged and contaminated the sample—and just maybe, dropped off Jassa at another destination.

An underwater scene with algae and fan worms

Plant and animal life on a floating dock edge in Australia. The North Atlantic Jassa marmorata was first detected in Australia in 1881. The beautiful fan worms (upper half of the photo) are also an introduced species. Image: Kathleen Conlan, © Canadian Museum of Nature.

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War Ornithologists

The two great wars that marked the first half of the 20th century saw a substantial number of recruits mobilized and sent to the front. Given that the recruits were from all walks of life, inevitably there were some who were passionate about the natural sciences. Despite harrowing living conditions, some soldiers tried to document the “natural” environment in which they were immersed. The Canadian Museum of Nature holds specimens dating from these difficult times; here are three examples.


Left: a magpie collected in Flanders in March 1917 by Major Allan Brooks. Catalogue number: CMNAV 13020. Eurasian Magpie (Pica pica). Image : Michel Gosselin © Canadian Museum of Nature Right: Major Allan Brooks. Image from the Biodiversity Heritage Library. Public domain.

Allan Brooks (1869–1946) was a wildlife artist living in British Columbia. He had joined the militia even before the start of the First World War, and spent the entire period from 1914 to 1918 in England and France.

In 1917, he was posted at Mont des Cats in Flanders (a place that would be the scene of a significant German offensive). It was there that he was able to collect some bird specimens, and pass them on to his colleague Percy Taverner, the first ornithologist of what is now the Canadian Museum of Nature. It is known that Brooks partly lost his hearing while at the front, to the point where he said he was “no longer able to hear the song of the skylark”

Upon his discharge, Allan Brooks had reached the rank of lieutenant-colonel. Back home, he contributed illustrations to Percy Taverner’s 1926 Birds of Western Canada. Brooks deposited many of his European specimens with the Canadian Museum of Nature.

Birds in the War-Zone, written in October 1916, describes his ornithological observations in Europe. Notably, he wrote that some birds did not seem to be unduly affected by artillery fire, which sometimes lasted for hours.

Ventral view of a quail specimen and a close-up view of one of the tags attached to the bird's feet. Showing the text: Coturnix c. coturnix L .; 29.V.1943; Kasar bei Orel, Russland.

The Canadian Museum of Nature has specimens from both sides of the front. Here, a quail collected in Russia in 1943 by a soldier of the German army. Catalogue number: CMNAV 68810. Common Quail (Coturnix coturnix). Image: Michel Gosselin © Canadian Museum of Nature.

The young Viennese ornithologist Rudolf Tomek (1913–1943) was an employee of the Provincial Museum of Lower Austria. When Germany annexed Austria, he was conscripted into the army and sent to the front, in Russia, in 1942. The following year, he was killed during a Russian counteroffensive in the Orel region, south of Moscow.

Tomek had managed to send some birds collected in Russia to the Vienna Museum of Natural History. By a singular combination of circumstances, one of these specimens (a Common Quail) was part of a 1979 exchange of specimens between this Austrian museum and the Canadian Museum of Nature.

Ventral view of a Grey-faced Buzzard specimen and close-up view of the tags attached to the bird's legs. It reads among others: Japan, Okinawa; Butastur indicus; October 13, 1945; A. R. Phillips.

This hawk is among the specimens collected by Corporal Allan R. Phillips as part of research on Japanese encephalitis vectors on Okinawa Island after the US landing in 1945. Catalogue number: CMNAV 96710. Grey-faced Buzzard (Butastur indicus). Image: Michel Gosselin © Canadian Museum of Nature.

Allan R. Phillips (1914–1996) was a biologist best known for his work on the birds of Arizona and Mexico. In 1942, while a doctoral student in ornithology at Cornell University (New York, USA), he was enlisted in the US Army.

After surviving the Normandy landing in 1944, he was dispatched to Japan during the invasion of Okinawa Island in 1945. On the island, he met by chance a Cornell colleague, Sergeant Frank Cassell, who assigned Phillips to medical research

Corporal Phillips thus found himself studying the birds of Okinawa Island as potential vectors of Japanese encephalitis. Some of the specimens collected during this period now belong to the Canadian Museum of Nature which acquired part of Phillips’ collections in 1980.

(Translated from French)

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One Hundred Lichens New to Quebec, Canada, and North America from the Gaspé Peninsula

In 2007, during an alpine ski touring trip in the backcountry of Parc national de la Gaspésie on the Gaspé Peninsula in eastern Quebec, I noticed a surprisingly rich lichen diversity. This discovery inspired me to begin an ongoing study of the park’s lichens.

I was not the first scientist drawn to Gaspé to explore lichens. In the late 1800’s, John Macoun, Canada’s first Dominion Botanist (and a lichenologist), collected specimens in the area that is now the park. In the early 1900’s, Merrit Fernald, a Harvard University professor and botanist, lead several trips to the region to study its plants and lichens.

A group of researchers pose in the field in 1923.

Merritt Fernald (furthest left) and his 1923 expedition team to the Gaspé Peninsula. Image: © Gray Herbarium Archives, Harvard University.

These pioneering collectors were the first of more than 40 researchers who have studied the park’s lichens. When I began my study, almost 300 lichen species were known in the park. There are now over 600 species, ranking the park among North America’s richest lichen locales.

Many of the new discoveries were made with the help of my colleagues during our annual gathering of lichenologists, the Tuckerman Workshop. We found 100 lichens in the park that had never been reported from Quebec. Twelve of these species are new to Canada and six of those are new to North America.

A yellow lichen, alongside the map of known specimens in North America.

The North American distribution of the limestone sunshine lichen, Vulpicida juniperinus. The population in Parc national de la Gaspésie is marked with a red triangle. Image: R. Troy McMullin © Canadian Museum of Nature.

The rich lichen biota in Parc national de la Gaspésie is due to its diverse habitats, including old-growth woodlands, different forest types, lush river valleys, and a coastal influence. The mountain summits also have arctic-alpine environments and contain species that otherwise only grow in the western mountains and the Arctic. For example, the limestone sunshine lichen Vulpicida juniperinus is at its southern range limit in eastern North America in the park. The closest population occurs over 1000 km to the north.

A view of lush forested park from the peak of a hill.

Parc national de la Gaspésie from the summit of Mount Albert. Image: R. Troy McMullin © Canadian Museum of Nature.

My lichen study in the park will continue until all corners have been explored and the discovery of new species becomes infrequent.

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Solving the mystery of a metal-oxide coating threatening to cover Mi’kmaq Petroglyphs in Nova Scotia

Laboriously carved into the rocky shores of lakes and rivers in central Nova Scotia are approximately 400 historic petroglyphs created by the people of the Mi’kmaq First Nation. These beautiful and elaborate images record intricate aspects of daily life, such as hunting and fishing, as well as the arrival of Europeans in the 18th and 19th centuries.

The preservation of these petroglyphs is under constant threat, whether from natural erosion, vandalism, or changing water levels caused by hydroelectric dams.

Since the 1990’s another threat has emerged: several of the petroglyphs on the shores of Kejimkujik Lake, in Kejimkujik National Park, have been overgrown by an unusual metal-oxide rock coating.

Now, Parks Canada conservation scientist Despoina Kavousanaki, Ph.D. and I are using some of the most advanced analytical techniques to determine the origin of this mysterious coating, and hopefully find ways to prevent it.

Our research began with using a state-of-the-art field-emission scanning electron microscope to map the distribution of metal elements on the surface of a small subsample of metal-oxide covered rock.

In a scanning electron microscope, electrons are bounced-off the surface of a sample to construct an image that provides data about the sample’s shape and chemical composition. The rock images revealed a distribution of the metals manganese and iron on the rock’s surface.

Did these elements originate from inside the rock, the lake water, or elsewhere?

A collage of four images showing rock samples as described in the caption.

Images taken of a sample of rock cut from near one of the Kejimkujuk Lake petroglyphs. (a) The original rock type (light colour) and the metal-oxide coating (dark colour). The average thickness of the coating is less than 1 mm. (b) A scanning electron micrograph of the coated region. Brighter colours reveal metal-rich regions. (c-d) A series of chemical maps showing the distribution of the elements on the rock surface, iron (Fe, blue) and manganese (Mn, green). More intensely-coloured regions are those with the highest metal concentration. Image: Aaron Lussier, © Canadian Museum of Nature.

To answer this question, we used a focused ion beam to remove a tiny section of the metallic coating so that we could image it with a transmission electron microscope. The focused ion beam uses a beam of gallium ions to cut a slice of rock just 65-nanometers thick, approximately 1,500 times thinner than the width of a human hair. In a transmission electron microscope, a powerful electron beam is shot right through the sample material and then used to construct an image, similar to how a normal microscope uses light waves. The transmission electron microscope is so powerful it can magnify objects more than one million times, almost imaging single atoms.

The images we collected in this way show an intricate array of extremely small mineral fragments. The shapes and textures of these hold important clues about the complex processes, whether natural or human, that may have instigated the movement and deposition of metal oxides on the rock surface. The shape and aggregation of the mineral fragments suggest the involvement of bacterial processes.

Samples of electron microscope data

Transmission electron microscope data collected on a subsample of the metal-oxide coating found on a Kejimkujuk petroglyph. Note the very small scale. General overview of the sample showing (a) the mineralogical/textural and (b) compositional complexity of coating. Each colour corresponds to a different mineral composition. (c) A high-resolution transmission electron microscope (TEM) image of a single grain of clay found in the sample, the observed parallel lines (e) result from the underlying atomic structure in the sample. (d) A higher-resolution TEM image of manganese-oxide nanoparticles. Image: Aaron Lussier, © Canadian Museum of Nature.

Our next step will be to make a detailed geological map of the areas of interest in order to assess the extent of the coating and correlate it with rock composition.

These analyses will enable us to better understand how the coating-related metals move in the local environment and how to make the best possible choices to ensure the preservation of this important First Nations heritage. Stay tuned!


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Fossil solved great dinosaur cheek debate

When I was recently asked to pick a significant fossil from the museum’s collection to profile in a video, I had a difficult time making up my mind – we have thousands of remarkable specimens. In the end my choice came down to an intriguing question: Did dinosaurs have cheeks?

As a museum paleontologist, much of my research focuses on the animals that lived in western North America during the Late Cretaceous epoch, about 80 to 70 million years ago, the end of the reign of the dinosaurs as the dominant group on the planet. So, it was a safe bet that my pick would be a Cretaceous dinosaur.

Then the skull of the armoured dinosaur Panoplosaurus mirus jumped to mind as definitely meriting some discussion.

Collected in 1917 from what’s now Dinosaur Provincial Park in Alberta, it’s the holotype, the specimen on which the species has been defined.

And, this well-preserved Panoplosaurus skull helped decide the debate about whether dinosaurs had cheeks.

Watch the video to learn the answer.

Want to meet Panoplosaurus mirus in person? Join me at our annual Open House at the Natural Heritage Campus in Gatineau on October 13, 2018, the behind-the-scenes event at the Museum’s research and collections facility.

I’ll be happy to answer any questions you have, and rest assured, I’ll refrain from any cheeky tones in my responses, even if we’re talking about Panoplosaurus!

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Undiscovered backyard biodiversity: New lichen species discovered in Guelph, Canada

You might think that the discovery of new species requires travel to distant and less explored parts of the world. In fact, they can still be found in our own backyards.

During a recent survey for lichens in The Arboretum at the University of Guelph, my colleagues and I discovered a new species of lichen, Chaenotheca selvae (McMullin et al. 2018).

A close up image of a stubble lichen species.

Chaenotheca selvae, a new species of lichen discovered in Guelph, Canada. Troy McMullin © Canadian Museum of Nature.

We named the species in honour of emeritus University of Maine professor, Dr. Steven Selva, for his more than three decades of important contributions to the study of stubble lichens and fungi, or calicioids, the group to which C. selvae belongs.

Stubble lichens and fungi are small (0.1 to 2 millimetres tall) stalked species that resemble facial stubble on the tree trunks and branches on which they live. They’re so small that they are often difficult to find, which might explain why the new species was overlooked until now.

We discovered 111 species of lichens and allied fungi in The Arboretum, including a new species to Canada, Caloplaca soralifera, and more than a dozen rare species, such as Bacidina egenula, which is only the third record of this species in Ontario (McMullin et al. 2014).


Bacidina egenula, known to occur at only three locales in Ontario. Troy McMullin © Canadian Museum of Nature.

Our research highlights the importance of protecting old-growth forests, particularly in areas where few remain, such as southern Ontario, as sources of rare and undiscovered biodiversity.

Chaenotheca selvae is also a tiny but powerful reminder that when we look carefully, new species await discovery right in our own backyards.


McMullin, R.T., J. Maloles, C. Earley, and S.G. Newmaster. 2014. The Arboretum at the University of Guelph, Ontario: An urban refuge for lichen biodiversity. North American Fungi 9: 1-16.

McMullin, R.T., J. Maloles, S. Selva, and S.G. Newmaster. 2018. A synopsis of the genus Chaenotheca in North America, including a new species from southern Ontario, C. selvae. Botany 96: 547–553.

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Finnish moth species is asexual with benefits

In central Finland there is a group of moths whose common name is bagworm moths because the larvae, or caterpillars, live in bags that they make from leaves and twigs. What’s even more noteworthy about these moths is that for many species males are unnecessary.

Bagworms belong to the family Psychidae which includes species living side-by-side in Finland that reproduce either sexually or asexually. This make these moths ideal for studying the ecological and evolutionary benefits of parthenogenesis—when a female’s eggs develop without being fertilized by a male, or asexually.

A brown moth larva next to a case made of forest debris

A wingless female bagworm moth (Dahlica fennicella) and its homemade case. Right, pupal remains. Image: Veronica Chevasco, © Veronica Chevasco

Sexual reproduction increases genetic variation and is thus central in evolution. However, what the parthenogenic bagworms are revealing is that asexuality may not be as limiting to a species’ survival as some have thought.

In fact, my research with bagworms shows that asexuality can be an adaptive advantage rather than an evolutionary dead end.

For example, by being parthenogenetic it appears that the bagworm species Dahlica fennicella is less vulnerable to wasp parasitism than related sexually reproducing moths.

It could be that behavioural differences between sexual and parthenogenetic species help D. fennicella avoid parasite attacks. It’s also possible that D. fennicella is successful because its offspring are not genetically identical clones, and with four sets of chromosomes, the multiple gene copies might overcome harmful mutations and even some parasitism.

A small brown moth seen from above.

Male bagworm moth (Dahlica fennicella). Image: Veronica Chevasco, © Veronica Chevasco.

Sexual and parthenogenetically reproducing moths look remarkably alike and so species must be identified using molecular methods, such as DNA barcoding. This molecular identification of sexual species shows that the parthenogenetic D. fennicella moth is a truly an asexual species, not a hybrid produced through the cross-breeding of two species of sexually reproducing bagmoths.

Four side-by-side images. A brown larva next to a brown case. An adult female moth. Two moth larvae. A wasp with long antennae and a long ovipositor.

(A) Bagworm larvae and their cases made from leaves and twigs. (B) A wingless, sessile female rests on her pupal case waiting for a mate. (C) A sessile, parthenogenetic bagworm moth. (D) A wasp that parasitizes bagworm moths. Image: Veronica Chevasco, © Veronica Chevasco

These bagworm moth findings don’t minimize the importance of sexual reproduction; parthenogenetic species generally evolve from sexual species and inherit diversity from their ancestral forms.

But the results do show that, among bagworm moths, parthenogenetic species appear to avoid the costs of sex while getting benefits from an asexual life.

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Collecting diatoms in sunny Italy: Citizen scientist brings specimens for museum’s collection

Last autumn I went on vacation with my brother to sunny Italy. Along with marvelling at St. Peter’s Basilica and eating great food, I did what any other keen museum volunteer would do: collect Italian freshwater diatoms for the museum’s collection.

A collage of various locations in Italy and the author.

Clockwise from top-left: St Peter’s Basilica, Vatican City; gondolas in Venice; Pompeii with looming Mt. Vesuvius; Valley of the Temples, Agrigento, Sicily; citizen scientist Joe Holmes beside the Silvestri Crater, Mt Etna, Sicily; Isle of Capri and Tyrrhenian Sea. Image: Joe Holmes © Canadian Museum of Nature.

Diatoms are fascinating, microscopic, one-celled algae, with a thin silica shell, measuring just five to 150 microns, or millionths of a meter.

A collage including a bridge over a river and several phytoplankton samples

Rome’s Tiber River looking toward the Sisto Bridge and St Peter’s Basilica. Two samples were taken here. The collected diatoms indicate alkaline pH, some brackishness, and moderate levels of organic nutrients. Left: Tryblionella constricta (36 µm x 6 µm). Second: Ulnaria acus (68 µm x 5 µm). Third: Frustulia vulgaris (44 µm x 10 µm). Right: Gyrosigma acuminatum (145 µm x 17 µm). Image: Joe Holmes © Canadian Museum of Nature.

These free-floating phytoplankton are the foundation of the aquatic food web, converting sunshine into stored chemical energy, and carbon dioxide into oxygen. Diatoms are found in all fresh and marine waters. Biologists use them for water quality analysis and climate change research.

A collage including a tower along a canal and several phytoplankton samples.

Florence’s Arno River Dam where a sample was taken at lower left. Top: Aulacoseira granulata (40 µm x 6 µm). Bottom-left: Gomphonema pala (23 µm x 10 µm). Middle: Diatoma vulgare (53 µm x 13 µm). Right: Encyonema prostratum (44 µm x 18 µm). Image: Joe Holmes © Canadian Museum of Nature.

Whenever I had free time during the trip, I collected various types of diatom samples, amassing a total of 41 from lakes, rivers, fountains and ponds across Italy, including Rome, Florence, Venice, and Sicily.

A collage including the author and several phytoplankton samples.

An irrigation canal near Pomposa on the Po River Delta. The diatoms were sampled using a mud retriever. They reveal the presence of higher levels of organic nutrients, likely from agricultural runoff. Left: Bacillaria paxillifera (55 µm x 4 µm). Second: Gomphonema insigne (57 µm x 11 µm). Top: Tryblionella levidensis (30 µm x 15 µm). Bottom: Cyclotella meneghiniana (12 µm x 12 µm). Image: Joe Holmes, © Canadian Museum of Nature.

Back at the lab in the museum’s collections facility, samples were processed, and specimens photographed and identified using an online Italian government diatom guide. Interestingly, the diatoms reveal a lot about Italian water quality and terrain at the sampled sites.

A collage including a pond in a garden and several phytoplankton samples.

The Aquarium pond in the Orto Botanico di Palermo, Palermo, Sicily. Left: Navicula radiosa (70 µm x 10 µm). Top: Pseudostaurosira brevistriata (30 µm x 15 µm). Middle: Cocconeis placentula (22 µm x 14 µm). Bottom: Rhoicosphenia abbreviata (32 µm x 9 µm). Image: Joe Holmes © Canadian Museum of Nature.

For example, most diatoms at sample sites indicate a preference for alkaline pH reflective of the limestone, volcanic and carbonate rocks that make up most of the Italian Peninsula. Some species are indicators of water with moderate to high levels of organic nutrients, likely from nearby farms. Lastly, some specimens indicate traces of brackish water, perhaps due to salt in the Italian soil or proximity to the Mediterranean Sea.

A collage including a river estuary and several phytoplankton samples.

Girgenti River Estuary, San Leone, Sicily. This is tidal water, with the Mediterranean Sea at left, so all the collected diatoms are marine species. Top: Achnanthes brevipes (27 µm x 8 µm) Second: Navicula ramosissima (43 µm x 7 µm) Third: Navicula longa var irregularis (48 µm x 9 µm) Bottom: Synedra fasciculata (31 µm x 6 µm). Image: Joe Holmes © Canadian Museum of Nature.

The trip yielded many of the same species of diatoms I’ve collected in Canada, Ireland and the Middle East.

A collage including a beach and several phytoplankton samples.

Torrente Santa Venera, Giardini Naxos, Sicily, looking southeast toward the Ionian Sea. Top: Nitzschia sigma (61 µm x 7 µm). Second: Nitzschia communis (29 µm x 4 µm). Third: Nitzschia recta (69 µm x 7 µm). Bottom: Navicula apiculata (34 µm x 9 µm). Image: Joe Holmes © Canadian Museum of Nature.

For museum diatom researchers and students these new Italian specimens are proof that some scientific souvenirs can provide a lot more than just good memories!

A collage including a beach and several phytoplankton samples.

Vigna di Valle, Bracciano Lake, the source of Rome’s water. The collected diatoms indicate that the water is relatively clean, with low nutrient levels. Top: Aneumastus tuscula (32 µm x 12 µm). Bottom-Left: Cocconeis neodiminuta (21 µm x 13 µm).  Middle: Raphoneis surirella (30 µm x 8 µm). Right: Cavinula pseudoscutiformis (12 µm x 9 µm). Image: Joe Holmes © Canadian Museum of Nature.








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