Ultrastructural study of spermatozoa of the neotropical lizards, Tropidurus semitaeniatus and Tropidurus torquatus (Squamata, Tropiduridae)

A detailed description of the sperm ultrastructure of Tropidurus semitaenia tus and T. torquatus is provided. Mature spermatozoa of T. semitaeniatus an d T. torquatus are filiform and characterized by: apical portion of acrosom e depressed; perforatorium single; epinuclear lucent zone well developed; m idpiece short; mitochondria columnar; midpiece with three sets of alternati ng ring structures and mitochondria (rs1/m1, rs2/m2, rs3/m3); nuclear shoul ders rounded; nucleus elongate; fibres 3 and 8 enlarged; and fibrous sheath in midpiece. Spermatozoa of Tropidurus are unusual in possessing a unilate ral electron-lucent ridge at the surface of the acrosome and an epinuclear electron-lucent zone. The two species are very similar, differing in detail s such as degree of acrosome flattening, presence of bulging at nuclear bas e, and arrangement of microtubules in the endpiece, Comparisons between Tro piduridae and other families of iguanian lizards are made.