Greetings Rony. As far as I know, there is no any taxonomical key designed for Guatemelan spider fauna. I've worked with spider diversity from the Guatemalan-Mexican border. There are several aranealogical works in that region of Mexico, called "Soconusco". I can reccomend you to contact Ph.D. Guillermo Ibarra Nuñez, one of the most renowned Mexican spider specialists. He works in ECOSUR Tapachula, you can find his contact information at this web: http://www.ecosur.mx/index.php?option=com_academicpages&id=224. He's also in ResearchGate, so you can downloand his latest works for free.