doi 10.5358/hsj.32.170 Current Herpetology 32(2): 170–181, August 2013 © 2013 by The Herpetological Society of Japan Annual Reproductive Cycle in the Scincid Lizard Chalcides viridanus from Tenerife, Canary Islands PAULA SÁNCHEZ-HERNÁNDEZ 1 , MIGUEL MOLINA-BORJA 1 *, AND MARTHA P. RAMÍREZ-PINILLA 2 1 Grupo de Investigación “Etología y Ecología del Comportamiento”, Depto. Biología Animal, Universidad de La Laguna, Tenerife, Islas Canarias, ESPAÑA 2 Laboratorio de Biología Reproductiva de Vertebrados, Grupo de Estudios en Biodiversidad, Escuela de Biología, Universidad Industrial de Santander, Bucaramanga COLOMBIA Abstract: Chalcides viridanus is a small skink endemic to Tenerife, the Canary Islands. This paper describes its annual reproductive cycle and sexual dimor- phism by use of data from external measurements, dissection, and histological observation of gonads from monthly samples. Males were significantly larger than females in head–forelimb length, distance between forelimbs and hind limbs, tail width, and body mass. Male testes were largest in March, when most individuals showed active spermiogenesis, although no spermiation was observed. In April, the testes were somewhat smaller but showed seminiferous tubules and epididymis ducts with abundant sperm. In this month, female gonads and ovarian follicles were significantly enlarged, and vitellogenesis was evident. Oviductal embryos were found in May and June, and parturition took place at the beginning of August. Both testis mass in males and diameter of the largest oocyte in females were significantly correlated to abdominal fat body mass. We conclude that in C. viridanus both sexes exhibit seasonal changes in gonadal activity with synchronous development of both male and female gonads in the spring months. Key words: Scincidae; Chalcides viridanus; Canary Islands; Reproductive cycle; Viviparity INTRODUCTION Knowledge of reproductive cycles and life- history traits in lizards is important both from a comparative point of view to understand their evolutionary processes (Dunham and Miles, 1985; Bauwens and Díaz-Uriarte, 1997; Mouton et al., 2012) and from a proximal causal approach to elucidation, for example, of responsible environmental factors (Ruben- stein and Wikelski, 2003; Carretero, 2006). Viviparity has supposedly originated on more than 108 separate occasions within the Squa- mata (Blackburn, 1999), and has often evolved relatively recently (Heulin and Guillaume, 1989; Camarillo, 1990). * Corresponding author. Tel: 34–922–31–83–41; Fax: 34–922–31–83–11; E-mail address: mmolina@ull.edu.es