Petshrimp.com Discussion Forum

Are there any obvious distinguishing characteristics between Cambarellus shufeldtii and C. schmitti? Something that can be done with the naked eye.

Positive identification is based on the structure of the first pleopod of a type I male.

To my knowledge, there is not a comprehensive set of diagrams comparing a wide range of anatomical features to allow positive identification by casual observation. I am picking up a book from inter-library loan today which is the "illustrated checklist of the american crayfishes". If it has more diagrams of Cambarellus than I have previously seen, I will make them available here.

Here is an online key to the genus, but you will need at least a good magnifying lens or dissecting scope to view the structure of the pleopod.

http://iz.carnegiemnh.org/crayfish/Keys/cambarellus.htm

Did you collect these crayfish yourself? If so, then the location of the collection site could also help determine which one is which.

Schmitti only occurs along the panhandle of Florida and in a tiny area of southwest Alabama. If you collected them in Mississippi or anywhere further west or north, then your crays would be more likely shufeldtii (or another Cambarellus species)

No, I received them from a local aquarium club member...who got them from another member of the same club, who got them off aquabid some time ago...

They're identified as C. shufeldtii. I have absolutely no reason to believe otherwise. However, since mine throw only mottled phase individuals, I'm getting some striped animals from a fellow in LA to increase my genetic variability. I'm sure there's no cause for concern, and I'm not one to get weird over hybrids (they happen in the wild - popluation biologists often cite a "10% rule"), but I was wondering if there are any "field marks" to identify the two species. I know the site you're talking about and I was hoping there was some way to do it without a dissecting scope.

Stripes inherit dominant in all Cambarellus I bred so far. So no need to wonder. If you have only mottled animals, you will only get mottled offspring.

Cambarellus schmitti comes in striped and mottled, too.

I just returned from the library with the "Holy Grail" for identifying American Crayfish.

It has illustrated diagrams of the carapace and chelipeds (claws) of all Cambarellus species which should be suitable for identification without the need for a dissecting scope. I'd suggest removing an individual, placing it in a shallow dish, and using a digital camera to photograph it from above.

When I get home later today, I'll scan some relevant pages and make them available here.

zwergkrebszuechter wrote:Stripes inherit dominant in all Cambarellus I bred so far. So no need to wonder. If you have only mottled animals, you will only get mottled offspring.

Cambarellus schmitti comes in striped and mottled, too.

Thanks for that bit of info - I figured it was a simple relationship like that and was hoping that it worked out that way (striped=dominant). Dominant alleles are easier to eliminate from a pop.

That's great news, YuccaP. I'll get a cray in here ASAP.

YuccaPatrol wrote:I just returned from the library with the "Holy Grail" for identifying American Crayfish.

It has illustrated diagrams of the carapace and chelipeds (claws) of all Cambarellus species which should be suitable for identification without the need for a dissecting scope. I'd suggest removing an individual, placing it in a shallow dish, and using a digital camera to photograph it from above.

When I get home later today, I'll scan some relevant pages and make them available here.

could you pm me that 'holy grail' info? i've got a few native species collected in different lakes/ponds/streams from around my area and they show a lot of variance depending on location, i'd like to be able to tell if they what they are exactly

I won't keep it a secret

I have borrowed the "Illustrated Checklist of the American Crayfishes" by Horton Hobbs Jr. published by the Smithsonian in 1989. It is #480 in the series of "Smithsonian Contributions to Zoology"

When it was published it was a FREE government publication, but the Smithsonian no longer has any copies available. Your best chance is to find it at a university library. I'd doing everything I can to find a personal copy for myself, but may end up having to make a photocopy of it before I have to return it.

If you can wait a year, all of this material from the Smithsonian is expected to be available free and online by the end of 2007.

IT's been a crazy week, but I'll try to scan and upload a few pages of the Cambarellus species info this weekend.

If you can wait a year, all of this material from the Smithsonian is expected to be available free and online by the end of 2007.

Thanks for the information Yucca. Do you know if the Smithsonian is going to make all of their material available online or is it just certain items?

From what the nice lady at the Smithsonian Scholarly Press told me, they are making all of their Contributions series available online here:

http://www.sil.si.edu/smithsoniancontri ... Browse.cfm

However, at this point, only the contributions to botany and earth sciences are available as full text to download.

At the moment, YP, it looks like a digital photo of my crays won't be happening any time soon. Fate is against me, here. In the meantime, is there any way you can scan some of those pics? I CAN get a cray under a magnifier.

Oh yes, let me scan a few of those pages.

I'll get them up as soon as I can.

Well, I used them...

Judging from the carapace, "my" dwarf crays looked...well, more like cajuns than anything else. The rostrum wasn't quite so sharply tapered, but they were close. The wild-caught ones I obtained recently had HUGE "horns" on either side of the rostrum. I flipped them both over for laughs, and the points of the pleopods were nice and straight. So, I can keep them together if necessary.

I thought the pleopods would be the difficult part, but they were rather easy...when the crays would hold still. A dissecting scope is amost too much magnification.