Tag Archives: myriapod

North America’s Big Five Centipedes

When Halloween comes around, snakes and spiders tend to steal the show. Yet centipedes, in my experience, tend to evoke even stronger reactions from people — I have met many entomologists who would happily handle a tarantula but recoil in horror when faced with a giant centipede.

In the United States there are five species of giant centipedes in the family Scolopendridae. Today, in the spirit of Halloween, I give you the Big Five: where they are found, what they do, and why I love them.

Blue Tree Centipede (Hemiscolopendra marginata)

The blue tree centipede. Photo by Sharon Moorman.

The blue tree centipede. Photo by Sharon Moorman.

This is the smallest of the five, seldom exceeding 3 inches, but still the largest centipede throughout most of its range. It is found through much of the East, from Ohio and Pennsylvania south to Florida and west to eastern Texas. Tree centipedes are also found in Mexico south to the Yucatan Peninsula. As the name suggests, the tree centipede is often an attractive blue-green, with yellow legs and orange fangs. The brightness of the color depends on the location, however, and some are paler than others.

The blue tree centipede is a habitat specialist, living under the bark of rotting trees, often before they have toppled to the ground. I have had the best luck finding them under the bark of pine logs. Because they are such good climbers, they occasionally wind up in buildings where they can cause quite a scare.

Bites from tree centipedes are painful but not much worse than a bee sting. They use their venom, as all centipedes do, to kill prey. Because they prefer to live in rotten pine logs, they may specialize in hunting beetle grubs that eat rotting wood. Like most centipedes, however, data on their feeding habits is severely lacking.

Green-striped Centipede (Scolopendra viridis)

The green-striped centipede is larger, reaching 6 inches or so, and usually pale yellow with a thick green or black stripe running down the back. Other patterns exist, however, and in parts of their range this species can appear more like a tree centipede or a tiger centipede (#4). These are adaptable centipedes, found from Florida west to Arizona, but don’t seem to venture further north than South Carolina.

The green-striped centipede. Photo by Jeff Hollenbeck, licensed under CC BY-ND-NC 1.0.

The green-striped centipede. Photo by Jeff Hollenbeck, licensed under CC BY-ND-NC 1.0.

Green-striped centipedes can live in a variety of habitats but they seem to prefer sandy forests. In Florida they can be found in scrub habitat, but like all centipedes they are not well-adapted to drought, and must stay moist by hiding underground or in rotting logs during the day.

Caribbean Giant Centipede (Scolopendra alternans)

The Caribbean giant is the only one of the Five with the russet-brown, mono-chromatic appearance of a “typical” centipede. It is probably our largest species, with a length easily exceeding 8 inches. However, the Caribbean giant is, as you might have guessed, a tropical centipede, and in the U.S. it lives only in southern Florida. It requires humid habitats, and the best place to find them is in and around the Everglades, in Dade and Monroe Counties.

A certain foreign species, the Vietnamese giant (Scolopendra subspinipes), is easily confused with the Caribbean giant at first glance. That wouldn’t be a concern, except that the Vietnamese giant has already become invasive in Hawaii and — this is just my speculating — is likely to become established in the Everglades at some point in the future. Because it is so large, often exceeding 10 inches, the Vietnamese giant is sometimes sold in the pet trade. Bites from either species are not deadly, but extremely painful.

Tiger Centipede (Scolopendra polymorpha)

A tiger centipede from Arizona. Photo by Sue Carnahan, licensed under CC BY-ND-NC 1.0.

A tiger centipede from Arizona. Photo by Sue Carnahan, licensed under CC BY-ND-NC 1.0.

Like the green-striped centipede, the tiger is a 6-inch-long animal found in a variety of habitats. Unlike the green-striped, this is a strictly western species, found from Idaho south through California into Mexico, and east all the way to Missouri. Its name comes from its color pattern: each segment is orange or yellow with a narrow, dark band.

Giant centipedes often move faster by undulating in a snake-like fashion, taking advantage of their long and muscular bodies. When a tiger centipede does this, the bands appear to “flicker,” rather like the brightly-banded milk snake and coral snake. This can make the centipede more difficult to track visually, and hence more difficult for a bird or mouse to grab.

Tiger centipedes, like their namesake, are voracious predators. They have been seen taking down prey much larger than themselves, including geckos and praying mantises. In turn, tiger centipedes are prey for scorpions, spiders, snakes, and many other predators.

A tiger centipede, fallen prey to a scorpion. Photo by Jasper Nance, licensed under CC BY-NC-ND 2.0.

A tiger centipede, fallen prey to a scorpion. Photo by Jasper Nance, licensed under CC BY-NC-ND 2.0.

Centipedes are adapted to moving fast, and their exoskeletons are thin and flexible. The drawback is that they dehydrate very easily. Although tiger centipedes are found in deserts, they still have to remain underground most of the time to conserve moisture.

Giant Desert Centipede (Scolopendra heros)

If you’ve ever seen centipedes used in a horror movie, they were probably heros*. They are big, reaching 8 inches or more. They are also brightly colored in black and orange — perfect for Halloween!

The Arizona form of the giant desert centipede. Photo by Aaron Goodwin, licensed under CC BY-ND-NC 1.0.

The Arizona form of the giant desert centipede. Photo by Aaron Goodwin, licensed under CC BY-ND-NC 1.0.

Heros are found in the desert Southwest, and color patterns vary by location. In eastern Texas and Oklahoma, they are typically jet-black with a bright orange head and yellow legs. In Arizona (above) they are usually red, with the first and last segments black. In New Mexico and western Texas the pattern is orange with black bands, much like a tiger centipede.

A giant desert centipede. Photo from NMNH Insect Zoo, licensed under CC BY-NC 2.0.

A giant desert centipede. Photo from NMNH Insect Zoo, licensed under CC BY-NC 2.0.

Why have black on just the head and the last segment? This an example of automimicry, in which one part of an animal’s body mimics the other. In this case, the tail-end of the giant desert centipede mimics its head-end. When faced with a giant centipede, predators usually attack the head, hoping to avoid a painful bite. If a predator gets confused, however, and attacks the tail instead, an unpleasant surprise awaits when the true head whips around to greet its attacker.

Centipedes, giant and otherwise, are pretty scary, and I never begrudge people who are afraid of them. Still, centipedes are amazing animals and if you see one, I encourage you to take a closer look. It will teach you, if nothing else, that just because an animal is frightening does not mean it can’t be beautiful.

*There is a centipede in one of the Human Centipede movies. People often tell me this after I tell them I study centipedes, so let me clarify a few things: I don’t know what kind of centipede the bad guy has for a pet. Not because I couldn’t identify it, but because I have never watched those movies and never will. I also don’t want to hear you describe your favorite scene with as many details as possible. Thank you.

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Basketballs, Shark Teeth, and Millipedes: Meet the Haplodesmids

by Joseph DeSisto

I feel like I’m on a roll with the whole common-name-inventing thing, so I’m going to have a go at another millipede family: the Haplodesmidae. These millipedes are poorly known, largely because they are often tiny and cave-dwelling. Beneath the microscope, however, they become utterly captivating. The haplodesmids have intricately shaped and textured exoskeletons, appearing almost as if they were crafted by an artist with very tiny instruments. For the purposes of this blog they will be called the “sculptured millipedes.”

For example:

The star-shaped haplodesmid Eutrichodesmus asteroides. Photo from Golovatch (2009b), licensed under CC BY 3.0.

The star-shaped haplodesmid Eutrichodesmus asteroides. Photo from Golovatch et al. (2009b), licensed under CC BY 3.0.

The millipede above has curled into a protective spiral, with its head at the center. The species name asteroides means “star-like” and refers to the shape formed when it spirals.

Here’s another, Eutrichodesmus incisus, newly described in Golovatch et al. (2009a) from remote Chinese caverns:

A preserved specimen of Eutrichodesmus incisus, shown under a scanning electron microscope. Photo from Golovatch et al. (2009a), licensed under CC BY 3.0.

A preserved specimen of Eutrichodesmus incisus, shown under a scanning electron microscope. Photo from Golovatch et al. (2009a), licensed under CC BY 3.0.

Notice the way the back plates, or tergites, have bumps and sutures like the surface of a basketball. They even look a little fuzzy, but it isn’t fuzz — each one of those tergites is covered in microscopic spines. Here’s a close look at the junction between a tergite and a prozonite (the part of a segment that goes before/under the tergite).

Tergite and pretergite of E. incisus. Photo from Golovatch et al. (2009a), licensed under CC BY 3.0.

Tergite and prozonite of E. incisus. Photo from Golovatch et al. (2009a), licensed under CC BY 3.0.

The tergite and prozonite have very different textures! Not only is the tergite bumpy, each bump is covered in tiny, finger-like projections or microvilli:

A single bump on a tergite of E. incisus. Photo from Golovatch et al. (2009a), licensed under CC BY 3.0.

A single bump on a tergite of E. incisus. Photo from Golovatch et al. (2009a), licensed under CC BY 3.0.

The prozonite, meanwhile, is covered in tiny spines. If we look even closer we can see that these spines even come in two different shapes, neatly arranged in rows like a shark’s teeth:

The surface of a pretergite of E. incisus. Photo from Golovatch et al. (2009a), licensed under CC BY 3.0.

The surface of a prozonite of E. incisus. Photo from Golovatch et al. (2009a), licensed under CC BY 3.0.

Pretty cool, right? At this point you’re probably wondering why sculptured millipedes look so weird, but I haven’t even shown you the weirdest one. The most bizarre-looking haplodesmid is star-shaped like E. asteroides, but even more so. Also like asteroides, it was only just described in 2009, from a series of Vietnamese caves (Gorovatch et al. 2009b).

The even-more star-shaped Eutrichodesmus aster. Photo from Golovatch et al. (2009b), licensed under CC BY 3.0.

The even-more star-shaped Eutrichodesmus aster. Photo from Golovatch et al. (2009b), licensed under CC BY 3.0.

Back to the obvious question: why are sculptured millipedes so sculptured? It’s an interesting question, but unfortunately not too much attention has been paid to the minute details of these already minute millipedes. In addition to being tiny, sculptured millipedes are also almost always found in caves, which are often remote and difficult to explore.

So, no one really knows why aster is star-shaped, or why incisus has tiny shark-teeth on its body. If I had to guess I would say that aster‘s projections make the millipedes more difficult to swallow, which is one of the reasons millipedes form spirals in the first place.

As for the teeth on the prozonites — I really haven’t got a clue.

The sculptured millipedes, like many invertebrate families, were barely known until a few intrepid taxonomists got to work on documenting the species. Now that this is starting to happen, perhaps we will find out what their strange projections/ridges/teeth/villi are for. I’m betting we will, and I certainly hope so — whatever reason there is, I’m sure it’s amazing.

Cited:

Golovatch S.I., J. Geoffroy, J. Mauries, and D. VandenSpiegel. 2009a. Review of the millipede family Haplodesmidae Cook, 1895, with descriptions of some new or poorly-known species (Diplopoda, Polydesmida). ZooKeys 7: 1-53

Golovatch S.I., J. Geoffroy, J. Mauries, and D. VandenSpiegel. 2009b. Review of the millipede genus Eutrichodesmus Silvestri, 1910 (Diplopoda, Polydesmida, Haplodesmidae) with descriptions of new species. ZooKeys 12: 1-46.

Mossy Millipedes: Meet the Platyrhacids

by Joseph DeSisto

I’ve been wanting to write an article about bryophytes — mosses and related plants — for some time now, ever since I was able to take a course on bryology here at UConn. Conveniently, bryophytes and invertebrates have formed some amazing relationships, giving me the perfect excuse to write about them! Today’s story comes from one such relationship, between several different bryophytes and an unusual millipede in the family Platyrhacidae.

A platyrhacid millipede, Nyssodesmus python, from Costa Rica. Photo by D. Gordon E. Robertson, licensed under CC BY-SA 3.0.

A platyrhacid millipede, Nyssodesmus python, from Costa Rica. Photo by D. Gordon E. Robertson, licensed under CC BY-SA 3.0.

The platyrhacids are just one of many “flat-backed” millipede families in the order Polydesmida, which itself accounts for roughly a third of the known millipede diversity. What makes the platyrhacids a bit odd-looking among other flat-backs is that their back plates (tergites) often have backwards-pointing triangular projections, like the enlarged scales on crocodile backs.

While other millipedes have such projections, and some platyrhacids do not, I’ll still take this opportunity to give platyrhacids a common name: the crocodile millipedes. The name works on a second level: just as crocodiles often have algae growing on their bodies, so does one crocodile millipede have mosses and liveworts growing on its tergites.

First, a primer on mosses and other bryophytes. Just as millipedes are one of the oldest terrestrial invertebrate lineages, so bryophytes are the oldest living land plants. Because of this, they are often regarded as primitive, but in fact bryophytes are both complex and incredibly diverse.

The resilience and diversity of mosses have allowed them to colonize an immense variety of habitats. Photo by Thomas Bresson, licensed under CC BY 3.0.

The resilience and diversity of mosses have allowed them to colonize an immense variety of habitats. Photo by Thomas Bresson, licensed under CC BY 3.0.

Mosses and liverworts grow all over the place, from streams and on the surfaces of tree leaves to bare rock and the sides of houses. Their ability to colonize new habitats is aided by their modes of reproduction: in addition to producing microscopic spores, bryophytes can develop from broken-off fragments. A study by Lewis et al. (2014) suggests that some moss populations owe their existence to tiny moss fragments spread by birds migrating from Alaska to sub-Antarctic Chile!

Now let’s get back to crocodile millipedes. The species in question is Psammodesmus bryophorus, which I’m going to call the mossy crocodile millipede. The mossy crocodile millipede was discovered in a mountain rainforest, high in the Andes of Colombia (Hoffman et al. 2011 — incidentally this was one of the last new millipedes described by Hoffman, one of the greatest millipede taxonomists of all time).

The mossy crocodile millipede, , complete with its bryophyte camouflage. Photo from Martinez-Torres et al. (2011), licensed under CC BY 4.0.

The mossy crocodile millipede, Psammodesmus bryophorus, complete with its bryophyte camouflage. Photo from Martínez-Torres et al. (2011), licensed under CC BY 4.0.

These millipedes are not common — only 22 specimens could be found in the site where they were discovered, the Río Nambi Natural Reserve. Of those, 15 specimens carried at least one, and typically many, moss or liverwort species on their backs (Martínez-Torres et al. 2011). Although moss spores are often spread by insects, for bryophytes to actually be growing on an animal is unusual. Among arthropods, only a few kinds of weevil and one harvestman have been reported carrying just a few moss species.

And yet, Martínez-Torres et al. (2011) report on their specimens “complex mosaics of bryophyte species.” Not only were the millipedes carrying bryophytes, they were carrying ten different species, in five different families! Many of these had never been reported as living on arthropod exoskeletons before, making this a big discovery both for diplopodologists (millipede scientists) and bryologists.

A liverwort growing on one of the tergites of the mossy crocodile millipede. Photo from Martinez-Torres et al. (2011), licensed under CC BY 4.0.

A liverwort growing on one of the tergites of the mossy crocodile millipede. Photo from Martínez-Torres et al. (2011), licensed under CC BY 4.0.

This may not be a totally symbiotic relationship — it’s entirely possible that the mosses and liverworts benefit only by having a growing site, while the millipedes get a nice suit of camouflage. All ten of the bryophytes here are also found either on soil or on the surfaces of other plants. Even so, it’s tempting to think there might be a more complex relationship.

Perhaps the millipedes help the bryophytes disperse their offspring. Or maybe the millipedes deter tiny animals that might eat the mosses, since millipedes are essentially walking cyanide bombs. We can only hope more mossy crocodile millipedes will be found — perhaps then we can get a better idea of what’s really going on in the mountain forests of Colombia.

I know I said only Tuesday and Thursday, but I’m on a bit of a writing binge right now. If you’re someone who gets an e-mail notification every time I post a new article … sorry about that (only a little). When I come down from whatever this is, things will normalize, I promise.

For an excellent blog devoted to bryophytes, be sure to check out Moss Plants and More by Jessica Budke.

Cited:

Hoffman R., D. Martínez, and A.E.F. Daza 2011. A new Colombian species in the millipede genus Psammodesmus, symbiotic host for bryophytes (Polydesmida: Platyrhacidae). Zootaxa 3015: 52-60.

Lewis L.R., E. Behling, H. Gousse, E. Qian, C.S. Elphick, J.F. Lamarre, J. Bêty, J. Liebezeit, R. Rozzi, and B. Goffinet. 2014. First evidence of bryophyte diaspores in the plumage of transequatorial migrant birds. PeerJ 2:e424 doi: 10.7717/peerj.424

Martínez-Torres S.D., A.E.F. Daza, and E.L. Linares-Castillo. 2011. Meeting between kingdoms: Discovery of a close association between Diplopoda and Bryophyta in a transitional Andean-Pacific forest in Colombia. International Journal of Myriapodology 6: 29-36.

Key-making: Illustrating the Stone Centipedes of New England

by Joseph DeSisto

Have you been waiting on the edge of your seat for an identification key to the New England stone centipedes? Do you often find yourself up late at night, eagerly searching for recent articles in taxonomic journals, only to have your chilopodological hopes dashed?

Well, your wait is (nearly) over! This week I started illustrating a key to the stone centipedes of New England. A total of 18 species are represented, the product of more than a year of relentlessly identifying hundreds upon hundreds of museum specimens, but the key is finally coming! It will be ready to send off to a journal by the end of the semester.

It will be ready. It will be ready. It will be ready.

Fangs! Photo by Joseph DeSisto.

Fangs! Because, fangs! Photo by Joseph DeSisto.

Anyway, I spent today working on line drawings, and I’ve included a few outlines here — note that the images below are not the images that will appear in the key itself. Rather, these are preliminary outlines I have made to provide a template for the final illustrations. They still need a lot of work, including shading.

The outline of the photo from earlier looks like this:

The prosternum (with fangs!) of Bothropolys multidentatus, one of New England's largest and commonest stone centipedes. Illustration by Joseph DeSisto.

The prosternum (with fangs!) of Bothropolys multidentatus, one of New England’s largest and commonest stone centipedes. Illustration by Joseph DeSisto.

Not bad for a first go, huh? Actually it was my fourth or fifth go, but moving on …

How does this work? First, I use a fancy microscope and an extra-fancy image-stacking computer program to make nice clear images of a centipede feature like the one above. Then I print out that photograph, and use a micron pen to outline, directly on the picture, the drawing I want to create. When the photograph is sufficiently defiled by lines, scribbles crossing out lines, and more lines, I put the paper on a light box and copy my outline onto tracing paper.

Then I copy that onto another piece of tracing paper. And another. And another, until finally I have one that’s good enough to look at without cringing.

The centipede from earlier is Bothropolys multidentatus, a common and large centipede in New England. Below I’ve illustrated the pores on the coxae (basal segments) of the 14th pair of legs:

The 14th coxae, viewed from below, of Bothropolys multidentatus. Illustration by Joseph DeSisto.

The 14th coxae, viewed from below, of Bothropolys multidentatus. Illustration by Joseph DeSisto.

The last two illustrations, you may have noticed, are roughly symmetrical. Real specimens are hardly ever that perfect — to make the illustrations look a bit nicer, and fit better on the page, I traced one half first and then traced its mirror image. In other words, the outlines are symmetrical because each side of the line drawing actually shows the same side of the original specimen.

Here’s a special one. This sexy leg belongs to a male Nadabius aristeus, a common but smaller New England centipede. There are two important features I’m trying to show here. First, there are two claws, rather than just one, at the end of the leg. Second, the hairy crest on the tibia is unique to males the genus Nadabius.

One of the terminal legs of a male Nadabius aristeus. Illustration by Joseph DeSisto.

One of the terminal legs of a male Nadabius aristeus. The tarsus/foot is at the bottom. Illustration by Joseph DeSisto.

Female centipedes be like, damn!

Common Names for a Few Centipedes

by Joseph DeSisto

Few, if any, centipedes have common names. Presumably this is because they are often perceived as being uncharismatic. Here’s why they should get common names:

1) Centipedes are too charismatic.

2) Yes they are.

Below I’ve listed every species of soil centipede known from New England. Soil centipedes belong to the order Geophilomorpha, one of four centipede orders found in North America — so this list is far from complete. I’ve provided a Latin name, a proposed common name, and a brief explanation.

Arenophilus bipuncticeps, the northern short-clawed centipede

Northern because it’s the only Arenophilus found in the northeastern U.S., short-clawed because the claws on its last pair of legs are short and stubby and adorable.

Geophilus vittatus, the diamondback soil centipede

This is one of the prettiest centipedes around, and here in New England, we are lucky because it is also one of the commonest. It is a pale yellow like most centipedes, but with dark diamond-shaped markings running down the back. They are found in a variety of habitats, but are especially easy to find if you peel loose bark off dead stumps and logs.

The diamondback soil centipede (Geophilus vittatus), one of my favorites. You can find this centipede in the northeastern United States by peeling away loose bark from dead stumps and logs. Photo by Tom Murray.

The diamondback soil centipede (Geophilus vittatus), one of my favorites. Photo by Tom Murray.

Geophilus mordax, the pitted soil centipede

G. mordax is a strange centipede, and in reality probably includes two species: mordax in the south and virginiensis in the northern part of its range. For now, though, the two species are united by the presence of pit-like structures (sacculi) on each of the sternites or belly plates.

Geophilus cayugae, the montane soil centipede

According to Crabill (1952) G. cayugae prefers high elevations. Other than that, this species isn’t all that distinct.

Geophilus terranovae, the Newfoundland soil centipede

Here’s a cool one. Terranovae was described by Palmen in the 1950s from Newfoundland, and since no one had recorded it elsewhere, the centipede was assumed to be endemic to Newfoundland. But just this year, I found specimens of terranovae from New Hampshire, so although this is clearly a boreal species, it has a much wider range than previously thought.

Geophilus flavus, the boreal yellow-headed soil centipede

This is one of our largest soil centipedes, an introduced species from Europe. It is also yellow-white, with a darker head, and often found in gardens. This species is common in my home state of Maine but I have yet to find any in Connecticut. I suspect this is because G. flavus prefers a more northern climate, with cooler temperatures and pine-dominated forests.

This name is a little long, but there are a lot of soil centipedes out there. It looks like long names might just have to be the norm.

The venom-injecting fangs of the northern yellow-headed soil centipede (Geophilus flavus). Photo by Joseph DeSisto.

The venom-injecting fangs of the boreal yellow-headed soil centipede (Geophilus flavus). Photo by Joseph DeSisto.

Strigamia bothriopus, the red pin-head centipede

Species in the genus Strigamia are a mix of beautiful, weird, and horrifying. Many are brightly colored, and in New England bothriopus is one of the prettiest, the vivid red hue of a Maraschino cherry. They also have tiny heads, which is sort of adorable, until you learn what they’re for.

Strigamia have an extra claw on their venom-injecting fangs, causing them to look sort of like a can-opener. In function this is not inaccurate, but instead of opening cans, pin-head centipedes use their claws to open up the abdomens of insects. The tiny head can then be inserted into the insect — this way, Strigamia can lap up the nutritious insides of its prey without having to chew through lots of exoskeleton.

Strigamia chionophila, the boreal pin-head centipede

Chionophila is similar to bothriopus, but smaller and less brightly colored. This species is also more common in boreal habitats, gradually replacing bothriopus as the climate cools to the north.

The red pin-head centipede (Strigamia bothriopus). Photo by Tom Murray.

The red pin-head centipede (Strigamia bothriopus). Photo by Tom Murray.

Pachymerium ferrugineum, the long-jawed shore-crawler

This is by far my favorite New England soil centipede, but unfortunately it is one of the least common. The shore-crawler gets its name from the fact that it’s fangs are relatively large for its body size, and that it is often found in the intertidal zone. Beneath rocks and seaweed, it feeds on barnacles, amphipods, worms, and other marine invertebrates. This centipede can even tolerate extended periods of immersion in salt water!

For this reason, I’ve named ferrugineum the “shore-crawler” rather than the “shore centipede.” Shore-crawler sounds cooler, and cool centipedes get cool names.

Schendyla nemorensis, the clawless soil centipede

This centipede is small and inconspicuous, but one of the most widespread soil centipedes in the world. It exists in Europe as well as much of northern North America, where it is thought to have been introduced by humans, but in fact it may have been here long before us. The name comes from the fact that its last pair of legs lack tarsal claws, for reasons unknown.

Escaryus liber, the Appalachian winter centipede

Like all members of the genus Escaryus, this species is highly cold-tolerant and can remain active through the winter, beneath the frost line. I have examined winter centipedes that were caught in pitfall traps as early as January — my suspicion is that this adaptation allows them to feed on defenseless, hibernating insects, giving them a head start in the coming year.

A soil centipede chomps down on an earthworm ... a little ambitious, perhaps? Photo by Tom Murray.

A soil centipede chomps down on an earthworm … a little ambitious, perhaps? Photo by Tom Murray.

Escaryus urbicus, the short-faced winter centipede

In North America, this is the northernmost representative of Escaryus, and the one you would expect to find in New England. In truth, all winter centipedes have relatively short “faces,” and fangs that don’t extend past the front margin of the head. But only one species could have that common name, so this was it.

Obviously nothing about this list is official — I’d love to hear your thoughts on how the names could be improved. Centipedes, like many invertebrates, are nightmarish to many, fascinating to some, and beautiful to only a few. Perhaps by making them more accessible to the public, we can reveal them for what they truly are: awe-inspiring, magnificent, and ultimately beautiful nightmares.

Some Strange Male Centipedes

by Joseph DeSisto

Time for some centipedes! Recently I’ve been looking at a lot of centipedes in the family Lithobiidae, and in particular the striking modifications of some of the males, and I thought I’d share them here.

For those of you who don’t spend your free time studying centipedes, they are arthropods with 15 or more pairs of legs and venomous fangs. I say “fangs,” but they are technically a highly modified pair of legs, positioned beneath the head, that centipede biologists may refer to as poison claws, forcipules, maxillipeds, prehensors, prehensorial feet, forcipular telopodites, toxicognaths (Bonato et al. 2010) … you get the picture. Fangs. They look like this, when viewed from below:

multidentatus

Bothropolys multidentatus, a common lithobiid centipede from eastern North America, viewed from beneath. Photo by Joseph DeSisto.

The fangs are the things that look like fangs. Pretty cool, huh?

Lithobiid centipedes belong to the order Lithobiomorpha, which includes centipedes with flattened bodies, spiracles (breathing holes) on the sides of their body, and 15 pairs of legs as adults. They are also show anamorphic development, which means the young add legs as they grow until they reach the final 15. Those in the family Lithobiidae have spines or spurs on their legs, which are helpful in identification.

Without a microscope, all lithobiids look pretty much the same. Some are bigger than others, but here in the eastern U.S. none exceed an inch or so. But on a smaller scale, the diversity in body form is fantastic, and one of the reasons they are probably my favorite family of centipedes.

To tell the difference between males and females, we need to move our view to the rear end of the centipede, and look at it again from beneath. While males are pretty nondescript in this regard, the females have a set of gonopod claws, which they use to manipulate the eggs they lay. A female centipede can lay an egg and then carry it around with her until she finds a suitable place to leave it, then use her legs and claws to coat the egg in dirt for camouflage .

Gonopod Claws

The gonopod claws on a female lithobiid, Lithobius forficatus. Please excuse the red writing, I originally made this image for a poster. Photo by Joseph DeSisto.

But in a few North American lithobiids, the males make themselves known by other means. This is most obvious in the last two pairs of legs, which may be highly modified into strange, contorted forms. Here’s an example, viewed from the side:

A male centipede in the genus Pearsobius. Photo by Joseph DeSisto.

A male centipede in the genus Pearsobius. Photo by Joseph DeSisto.

Pearsobius is a poorly known genus from Virginia and North Carolina (Causey 1942). The specimen above is unidentified. There will be a later post devoted just to Pearsobius, but for now, let’s look at more pictures! Pictures are great.

Male Pearsobius again, this time viewed from above. Photo by Joseph DeSisto.

Male Pearsobius again, this time viewed from above. Photo by Joseph DeSisto.

These centipedes are about half an inch in length, but the “spike” on the femur of the last pair of legs is visible even without a microscope. Although impressive, the purpose of these structures is unclear. My best guess is that the females use them to recognize males of the same species. While butterflies might use colors to achieve this effect, and birds might use songs, female centipedes live their lives in leaf litter and soil, where sight are of little use, and they can’t hear. So in an area where multiple centipede species might roam the same patch of leaf litter, a female needs something she can feel to avoid getting friendly with a male of a different species.

Not all leg modifications are so striking. Here is the 15th pair of legs on a male Paitobius zinus, also from Virginia.

The 15th pair of legs on a male Paitobius zinus from western Virginia. Photo by Joseph DeSisto.

The 15th pair of legs on a male Paitobius zinus from western Virginia. Photo by Joseph DeSisto.

Not as cool as a massive spike, but the modification here (the long indent on one of the segments) is still enough to make Paitobius distinguishable from other lithobiid genera. However, in Paitobius zinus, this is not the most striking male modification. Uniquely in this species, the male and female fangs/forcipules are different. The female’s forcipules are normal, and look pretty much like the ones from earlier (on Bothropolys). The male’s however … well, they look like this:

The forcipules on a male Paitobius zinus. Photo by Joseph DeSisto.

The forcipules on a male Paitobius zinus. Photo by Joseph DeSisto.

Yeah.

So far, P. zinus is the only species known to have modified male forcipules, and nobody knows why they have these. Long, narrow fangs could be an adaptation to extracting prey from narrow spaces (like in the woodlouse-eating spider, Dysdera crocata) … but why aren’t they found in females? Usually when we find a structure that is present in one sex but not the other, the function is related to reproduction. But as far as we know, the only thing forcipules are used for is killing prey.

Crabill (1960) was the first to write about this phenomenon in P. zinus, and since then, not a single person has bothered to study it. Why? Because despite being totally and undeniably awesome, centipedes are hard, and barely anyone studies them. I am currently planning a summer collecting trip to Virginia, though, and while I’m there I’ll see if I can learn anything. I have no idea why this species is so strange, but whatever reason there is, I bet it’s amazing.

A big thank you is owed to Dr. Bill Shear at Hampden-Sydney College in Virginia, who kindly sent me the specimens of Pearsobius and Paitobius, which he collected.

Cited:

Bonato, L., G. Edgecombe, J. Lewis, A. Minelli, L. Pereira, R. Shelley, and M. Zapparoli. 2010. A common terminology for the external anatomy of centipedes (Chilopoda). ZooKeys 69: 17-51.

Causey, N.B. 1942. New lithobiid centipedes from North Carolina. Journal of the Elisha Mitchell Scientific Society 58: 79-83.

Crabill Jr., R.E. 1960. A remarkable form of sexual dimorphism in a centipede (Chilopoda: Lithobiomorpha: Lithobiidae). Entomological News 71: 156-161.