I say kee-toe as in polyCHAETe (poly-keet), larvAE (lar-vEE) or algAE (al-gEE).
My bio professor always tells us that there aren't many hard and fast rules for saying scientific names other than to say it like the experts do.
Scientific names don't really follow all of the proper Latin rules, but then again Latin is a dead language, so no one knows for sure how it is really supposed to be pronounced anyway.