Araxyte spiders breeding araxyte spiders was a bug. The only way to obtain an actual araxyte spider is from killing Araxxi. This now means that only the 'shiny' araxyte spiders can be bred which will correctly tick off the breeding log. Previously it was possible to breed a non shiny which was confusing people as to why their breeding log was not ticked off. Hope this helps =)
Edit - Araxyte spiders now default to breeding spirit spiders.