Acta Zoologica (Stockholm) 88: 189– 197 ( July 2007) doi: 10.1111/j.1463-6395.2007.00265.x © 2007 The Authors Journal compilation © 2007 The Royal Swedish Academy of Sciences  Abstract Tavares-Bastos, L., Cunha, L.D., Colli, G.R. and Báo, S.N. 2007. Ultrastructure of spermatozoa of scolecophidian snakes (Lepidosauria, Squamata). — Acta Zoologica (Stockholm) 88: 189–197 We provide a detailed description of the sperm ultrastructure of three species of scolecophidian snakes, Leptotyphlops koppesi (Leptotyphlopidae), Typhlops reticulatus (Typhlopidae) and Liotyphlops beui (Anomalepididae), and make comparisons with the spermatozoa of Ramphotyphlops waitii (Typhlopidae) (Harding et al. 1995). All the species studied bear synapomorphies of Squamata and Serpentes. Among scolecophidian snakes, we identified eight polymorphic characters. Previous analyses of molecular and somatic morphological data provide equivocal solutions to the relationships among Anomalepididae, Lepto- typhlopidae and Typhlopidae. A close relationship between Anomalepididae and Typhlopidae is corroborated by two characters of sperm ultrastructure, presence of an electron-dense structure inside the proximal centriole and rounded mitochondria in transverse sections of T. reticulatus, Li. beui and R. waitii, whereas the absence of the ridge on the acrosome surface of Le. koppesi and T. reticulatus support a closer relationship between Typhlopidae and Leptotyphlopidae. The differences observed in sperm ultrastructure within Typhlopidae suggest the existence of snake intrafamilial polymorphism. The sperm characters of blindsnakes contain significant phylogenetic information and may provide important data for snake phylogenetic reconstructions. Correspondence: Leonora Tavares-Bastos, Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília, 70919–970, Brasília, DF, Brazil. E-mail: leonora@unb.br Blackwell Publishing Ltd Ultrastructure of spermatozoa of scolecophidian snakes (Lepidosauria, Squamata) L. Tavares-Bastos, 1 L. D. Cunha, 2 G. R. Colli 3 and S. N. Báo 2 1 Programa de Pós-Graduação em Biologia Animal; 2 Departamento de Biologia Celular; 3 Departamento de Zoologia, Universidade de Brasília, 70919 – 900, Brasília, DF, Brazil Keywords: Anomalepididae, Leptotyphlopidae, snakes, spermatozoa, Typhlopidae, ultrastructure Accepted for publication: 1 December 2006 Introduction Snakes are divided into two major groups, Scolecophidia (blindsnakes) and Alethinophidia (typical snakes) (Cundall et al. 1993; Heise et al. 1995; Zaher 1998; Zaher and Rieppel 1999; Lee and Scanlon 2002; Vidal and Hedges 2002a,b, 2004). Scolecophidians retain many ancestral characteris- tics, associated with a subterranean life-style, and form a monophyletic assemblage (Rieppel 1988a; Cundall et al. 1993; Heise et al. 1995; Scanlon and Lee 2000; Tchernov et al. 2000; Vidal and Hedges 2002b), with three groups: Leptotyphlopidae, Typhlopidae and Anomalepididae (Underwood 1967; Groombridge 1979; Rieppel 1988a; Heise et al. 1995; Vidal and Hedges 2002b). Vidal and Hedges (2002b) using sequence data (for C-mos, 12S rRNA, 16S rRNA and cytochrome b) indicated that Leptotyphlopidae is the sister group of a clade formed by Anomalepididae and Typhlopidae. Somatic morphological data corroborated this analysis (Rieppel 1988b; Cundall et al. 1993; Scanlon and Lee 2000; Lee and Scanlon 2002), whereas Heise et al. (1995), also using sequence data (for 12S rRNA, 16S rRNA) concluded that Typhlopidae and Leptotyphlopidae are more closely related to each other than to Anomalepididae. Scolecophidians are fossorial with a small gape size and feed exclusively on ants and termites (Greene 1997; Zug et al. 2001; Vidal and Hedges 2004). They occur in tropical habitats. Members of Typhlopidae are cosmopolitan in tro- pical regions; Leptotyphlopidae range through the tropics and subtropics of Africa and the Americas, and south-west Asia, whereas Anomalepididae show disjunct distribution in Central and South America (Zug et al. 2001).