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Isopod ID Thread


Zephyr

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I posted this on another forum but I figure it will be a worthy addition here too. :P

Below are 8 species of sizable terrestrial isopod found in the eastern US. They can be found in many moist habitats, but some have their preferences. Although antennal segmentation and other characteristics are the best ways to distinguish isopods, I feel that the following pictures and descriptions are the most pragmatic way for the average hobbyist to identify his or her catch.

(Sorry in advance for the uncropped pictures; I didn't even think I would get this guide up today! :P)

Armadillidium nasatum

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This species is one of the two commonly found that can roll up into a ball. They can be found in a variety of habitats from leaf litter to cracks in landscaping rocks. Although most individuals aren't as colorful or as big as their cousin, some, like the erythristic individual pictured, can be very striking. When rolled up in a ball, this species leaves a small gap in the very center of the crease of its body.

Armadillidium vulgare

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These are the classic big rolly pollies everyone has kept as a pet at one time or another. They are found just about anywhere moist. Some individuals have bright yellow colors making them resemble other more uncommon species, but they can be distinguished by the fact that A. vulgare has an incredibly large range and does not leave a little gap when rolled up in a ball.

Cylisticus convexus

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This species has a leggy look and is often a strange grey-purple color. They can be found everywhere if you look hard enough but they prefer to hide inside of rotting wood. They are very fast and can roll up into a tear shape.

Oniscus asellus

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This is perhaps the only species of isopod on the list that is almost never found outside its preferred habitat. They can be incredibly large and have a white "skirting" on the sides of their body. They can be found in great numbers underneath moist, rotting bark, and sometimes around the wooden supports of compost heaps.

Philoscia muscorum

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This is a somewhat smaller species that prefers leaf litter on forest floors. They can also be found under logs and stones in forests. They are very fast and resemble roaches. Some individuals can be a very bright yellow or brick red. One of the ways they can be identified is that their head resembles a single black dot.

Porcellio scaber

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This is probably the most common isopod in many areas. They are usually a slate blue but can be orange, mottled yellow, mottled orange, gray, or a myriad of other color and pattern schemes. They have a rough appearance, and when flipped over, have two pairs of white gills on the underside of their "tail." They also have a small horn-like bump between their eyes, which can distinguish them from several other species.

Porcellio spinicornis

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P. spinicornis is, in my opinion, one of the most attractive isopods. Individuals often have a large amount of yellow coloration with contrastingly darker heads. They can be tricky to distinguish from P. scaber, especially if the individual in question lacks a lot of yellow, but generally the presence of even a bit of yellow spotting indicates that it is P. spinicornis. They prefer to hide around stones, bricks, and cement blocks, but can be found pretty much anywhere else.

Trachelipus rathkii

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This is the most difficult species to distinguish from P. scaber. The two have color forms that look very similar, but T. rathkii is more commonly found having the shown mottled red-gray color pattern. When flipped over, T. rathki has 5 pairs of white gills on the "tail", whereas P. scaber only has 2 pairs. T. rathkii prefers rotting logs but can be found anywhere moist.

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Brilliant guide, Zephyr!

Do you have any Porcellionides pruinosus (http://bugguide.net/node/view/150093/bgimage)? I've been breeding the little dudes for years without knowing what they were, and I just noticed they weren't here. ;)

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Brilliant guide, Zephyr!

Do you have any Porcellionides pruinosus (http://bugguide.net/node/view/150093/bgimage)? I've been breeding the little dudes for years without knowing what they were, and I just noticed they weren't here. ;)

I was actually thinking about putting those in the guide, but alas, they don't range here! :P

Funny story: when I brought back some bumblebee millipedes from Florida last year, there was a single male isopod mixed in with them. I'd never seen one quite like it with such a weird powdery blue shine... Of course I had to ID it and lo and behold, it was P. pruinosus. I would love to breed them if I could get my hands on a few. ;)

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what do they eat? and how long do they live?

also where can one buy some?

They eat anything. I'm not sure how long they live but the l male mentioned in my last post lived at least 8 months.

You can buy some online... Or you can go in your back yard and flip over some rocks. :P

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Great thread! I have a very small brownish orange species that it doing okay so far. I have no idea what they are, but they are maybe 3mm and are found inside and on rotting logs. I also have a few aquatic isopods, but not the kind that roll up into balls (that everybody asks for).

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Great thread! I have a very small brownish orange species that it doing okay so far. I have no idea what they are, but they are maybe 3mm and are found inside and on rotting logs. I also have a few aquatic isopods, but not the kind that roll up into balls (that everybody asks for).

I find these too; I decided not to include them in the guide as I figured I might be grabbing a mix of them and other species' babies accidentally. Here I generally find them under rotting pieces of wood or in cavities in rotting logs, but I have kept them in a small container with soil and just a leaf and they did okay.

Isopods.jpg

A lady who loved dart frogs too gave me some of these and now it flourished. I had Armadillidium vulgare in Los Angeles but didn't know how to take care them at that time.

I think those are Trichorina tomentosa. Peter, I just checked bugsincyberspace and I think you changed the scientific name you ID'd these guys as. I saw a pic of T. tomentosa on Bugguide, but I haven't used my microscope on my culture of these guys so I'm not sure if T. tomentosa is the right ID. Any thoughts? I'm also assuming these guys are either US natives/naturalized like other isopods in culture.

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Whoops, silly me!

JZSRCZMRDZSRCZQROZXRCZRZDZSRJZJLWLMZ1LGRHH7ZULRZJZYLELHZDLSZ2LSZLHQR2LLZWLMZRH.jpg

That's what I saw. Guess my mind saw tiny white woodlice and figured the ones in culture were the ones on Bugguide. D'oh!

(For the record the ones above are Platyarthrus hoffmannseggii. :P )

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  • 2 weeks later...

Great picture! I have a lot of different species but I have never seen one like this.

I will second both of these! Wow...

Not on your list, Porcellio laevis, in my area these can almost span a quarter with their length. Their size quickly diminishes in culture until the colony matures, it took about a year for mine to get any adults over 1/2" from parents 3/4" and greater in size(and then it was owned by those annoying white grain mites that build up). I will have to try to find some of these soon and post them (if its ok to add to your thread). :)

I believe these are the species that was being sold with the name "giant canyon isopod" in the past? Edit: Yep...just checked BIC and he has them listed as such.

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I will second both of these! Wow...

Not on your list, Porcellio laevis, in my area these can almost span a quarter with their length. Their size quickly diminishes in culture until the colony matures, it took about a year for mine to get any adults over 1/2" from parents 3/4" and greater in size(and then it was owned by those annoying white grain mites that build up). I will have to try to find some of these soon and post them (if its ok to add to your thread). :)

I believe these are the species that was being sold with the name "giant canyon isopod" in the past? Edit: Yep...just checked BIC and he has them listed as such.

Peter (bugsincyberspace.com) was selling them. I bought some. My Porcellio laevis were destroyed by grain mites too. :( I might have one or two left.

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