The best web page for information on the biology (and medical aspects) of Loxosceles is that of Rick Vetter at UC Davis - see below.

http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7468.html

 There is a pretty good amount of distribution data for Loxoceles, you might want to do a scholar.google.com search to see if there are local records for you.  In the earlier mentioned Vetter webpage the systematic revision of the genus by Gertsch and Ennik is the best place to start.  And wonderfully, the American Museum makes its publications free for which it should be praised.  See link below to the revision.

http://digitallibrary.amnh.org/handle/2246/981

You could try tracking health data for necrotic spider bites

Dr. Canyon, while that is a very useful type of studies for some diseases/infections, it is actually a very bad thing to do in this situation.  First, there are several studies that show the reported 'necrotic spider bites' are not spider bites (Staph aureus/MRSA infections often) as they occur in geographic regions where there are no brown recluses (except the occasional spider that moves along with household furniture).  So please do not use a general characteristic of necrosis to try to determine the distribution of recluses.  Second, most of the Loxosceles species are not known to bite and therefore the species in the southwest and parts of Mexico would not show up.   If you want, I would love to work with you on the 'recluse' problem in Hawaii (or elsewhere), which can be done by asking the public to bring in recluses (the news media love to publicize it).

Thanks a lot for your answers, are very helpful.

Hi Luis!

you could also check this website with some distributional maps of mexican species:

www.aracnidos.unam.mx

I hope you find it interesting

Luis, are you trying to study all of the Loxosceles specie in your area, in Mexico.  Or are you trying to find out the distribution of L. reclusa?

Hi robert, i am tryinf to find info for out of Mexico and for Mexico, because its for a scientific divulgation work for kids and youngs, its only for report to people that there is no danger of that species in my region.

Thanks a lot for your help

It is interesting that you wrote tonight as I just unpacked and took a look at the new book by Richard (Rick) Vetter called "The Brown Recluse Spider" published by Cornell University Press.  It looks good, and if I can relay any specific answers from the book to you, please ask.  I might even suggest doing a "public request for Brown Recluses" and see what is brought into you.  I can give you ideas for that if you want.

Thanks a lot for your help, i finish the poster last week, but for future works i ask you again, and i think to buy this book, sound interesting.

I can send you my poster to receive your coments, but the poster is in spanish.

Luis,  glad you have made progress.  Go ahead and post the poster here on your list of contributions.  My spanish is weak, but I have friends who can help me translate.  Others may be interested on RG as well.