ON CLOACAL GESTATION IN ANGEL SHARKS FROM SOUTHERN BRAZIL

The anatomy of the reproductive organs of the gravid female angel shar ks Squatina guggenheim and S. occulta was studied in specimens obtaine d by bottom trawling off southern Brazil from 1980 to 1997. Gestation of the species is lecithotrophic, lasts 11 months and is synchronized at the population level. The ovulation and onset of gestation occur in summer (January - February) and parturition takes place in spring (No vember-December). The gestation of Squatina has two phases: uterine ge station during the first 4 months and cloacal gestation during the las t 6 months. The transition between these phases occurs in the 5th mont h (May). During uterine gestation the uteri are turgid, distended long itudinally and transversally and constricted at both ends. Embryos dev elop within the closed uteri. During cloacal gestation thr dome-shaped uteri are contracted longitudinally and are constricted near the nida mental gland. At the posterior end, they are distended transversally t o form a wide opening into the cloaca. The cloaca is distended longitu dinally and transversally. The embryos complete their development with in the single, heart-shaped. uterine-cloacal chamber, that is open to the exterior through the cloacal vent. (C) 1997 The Fisheries Society of the British Isles