Hello Jane There is ( for me ) a simple way to tell them apart N rupicola has about 25 picogram of DNA per nucleus N cuatrecasasii about 32 picogram ( 1 pg = 10 to minus 12 gram) Ben J.M.Zonneveld Institute of Biology,Leiden University, Clusius lab Wassenaarse weg 64, 2333 AL Leiden, The Netherlands Zonneveld@rulbim.Leidenuniv.NL Fax: +31-71-5274999. min temp -10C (15F)