Oliver, S.C., Jamieson, B.G.M. and Scheltinga, D.M. 1996c. The ultrastructure of spermatozoa of Squamata. II. Agamidae, Varanidae, Colubridae, Elapidae, and Boidae (Reptilia). Herpetologica 52, 216-241.`
Spermatozoal synapomorphies for the Squamata s. strict. are extension of the flagellar fibrous sheath into the midpiece, the paracrystalline nature of the subacrosomal cone, a single perforatorium in place of the two or three of Sphenodontida and Chelonia, loss of the endonuclear canal, presence of sinuous mitochondria (though a columnar form is intuitively preferred), intermitochondrial dense bodies, an epinuclear electron-lucent region, and, equivocally, arrangement of the dense bodies as periodic rings. Each of the taxa "Sauria," Scincomorpha, Scincidae, and Iguania is not monophyletic. A suite of character states of the sperm of Varanus gouldii is known in the Sphenomorphus and egernid (Tiliqua scincoides) groups of the Scincidae and in the teiid, Cnemidophorus sexlineatus, although some are also seen in the agamid Pogona barbata. Cladistically, Pogona forms the sister-taxon of Varanus, but only the presence of ovoid perforatorial basal plates, which are not entirely similar, appears to be a varanid-agamid synapomorphy and is homoplasically present in Eugongylus group skinks. Snakes appear to be the sister-group of a Eugongylus group skinks + pygopod clade. Snake sperm have multilaminar sperm cell-membranes (an apomorphy shared only with the Pygopodidae) and are unique in the Squamata in the immense elongation of the midpiece; further, snake apomorphies are reduction of the epinuclear electron-lucent region and reduction or loss of the perforatorial base plate, and greater development of extracellular tubules than is known in any other squamate. Varanid-snake, iguanid-snake, and teiid-lacertid relationships are not cladistically upheld.