Identification, Images, & Information
For Insects, Spiders & Their Kin
For the United States & Canada
Flat-backed Millipede - Oxidus gracilis

Flat-backed Millipede - Oxidus gracilis
Amherst, Massachusetts, USA
July 18, 2004
Shot in our front garden hunting in the mulch. Not a very large speciemen, perhaps 20-25 mm.

whats it's diet?
what might it consume? thats a question on my part... reason i'm asking- I have a project I need to get some information over animals i've found in their natural habitat and took a picture off... I just so happen to get a picture like this one... of course it was on my kitchen floor but thats beside the point.

Oxidus gracilis (Koch, 1847)
These 5 photos are all of Oxidus gracilis, an Asian representative of the family Paradoxosomatidae (order Polydesmida) that has been introduced into North America and all the inhabited continents of the world. It is ubiquitous in the lower 48 states and the major provinces of Canada, and I think may well be the most widespread and abundant metazoan animal in the world, given the enormous populations that exist in cities and towns. Surprisingly, I did not find it in Alaska in summer 2006, so it appears to be absent from this state. The arthropod often becomes a pest here in the US and undergoes population explosions with literally tens of thousands of individuals. The family Paradoxosomatidae, the largest, with the most species, in the class Diplopoda, occurs natively on all inhabited continents of the world except North America, where 5 species have been introduced, so O. gracilis is a classical example of an exotic organism that has become introduced into distant parts of the world where the forces that hold its populations in check in its native area don't exist. For practical purposes, the family Paradoxosomatidae can be recognized by the dorsal transverse grooves on the "metazona" of each segment, clearly shown in the figs. The corners of the paranota (lateral segmental expansions on the dorsa) are relatively blunt and not extended; a superficially similar species, Asiomorpha coarctata (Saussure, 1869), has been introduced into peninsular Florida; on it the paranotal corners are prolonged, sharp, and acutely pointed. There are also marked differences in the genitalia, and the two species are not closely related.

Greenhouse millipede
The following taxonomic catergories for this beast, within the Order Polydesmida, are taken from Hoffman's Checklist of the Millipedes of North and Middle America (1999):

Tribe Sulciferini
Family Paradoxosomatidae
Suborder Paradoxosomatidea

Hope this helps!

Flat-backed millipede
This is the green house millipede, Oxidus gracilis. This species probably originated in Japan and is now widespread in temperate habitats worldwide. It is found throughout the United States.

Sorry, this is a flatbacked millipede in the large order Polydesmidae. Nice photo, though:-)

Eric & Troy,

I was looking at the guide pages for millipedes (to add this order in) and I am not sure if they are correct. Compare with Nature Serve's website.

Which part looks suspect?
Are you referring to Phylum Mandibulata? That appears to be a less used classification. Check these which are consistent with what I chose:
Tree of Life

Or was it something else entirely?

I think it was it a class or an order? I'm trying to figure out where to add the order Polydesmida...

Now I see. I rearranged some stuff. Thanks for catching that.

Thanks Eric,

I admit I don't know much about these critters, I'll update the info.