ATYPICAL REPRODUCTION AND SEXUAL DIMORPHISM OF THE TROPICAL BONAIRE ISLAND WHIPTAIL LIZARD, CNEMIDOPHORUS-MURINUS

We investigated reproduction, sexual dimorphism in color, and sexual d imorphism in body size of Cnemidophorus murinus, the endemic whiptail lizard of Bonaire, Netherlands Antilles, during a year-long study and two later recapture periods. Growth rate declines as C. murinus increa ses in size. Males reach reproductive maturity at smaller snout-vent l engths (SVL) than do females (73 vs 85 mm) but continue to grow to lar ger final SVL (151 vs 116 mm maximum SVL). Bonaire whiptails can live at least four years. Reproduction was aseasonal; enlarged ovarian foll icles and/or oviductal eggs in females and enlarged testes in males we re observed in every month with no peak period of reproduction. Fat bo dy growth, however, was strongly seasonal, and fat body mass was great est in the months immediately after the rainy season. Amount of fat st ored differed among three sites, and females stored more fat than male s. Clutch size is typically one very large egg, but some females may p roduce two eggs. Although clutch mass/body mass ratio is typical for t he genus, egg mass/body mass is greatest for any Cnemidophorus or Amei va known and among the highest for any lizard (x = 0.126). Dorsal colo r is sexually dimorphic; females are brown, and juvenile males are als o brown, changing to bright blue as they grow. However, many nudes nev er reach the brightest color morph and may retain the juvenile color f orm for years. Several features of the biology of C. murinus are unusu al for the genus and for lizards in general (size at reproductive matu rity, small clutch size, large relative egg mass, color variation in m ales).