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Abstract

Reproductive cycles of the southern coal skink (Eumeces anthracinus pluvialis) and the five-lined skink (E. fasciatus) were studied by examining museum specimens collected in Arkansas. Histological preparations of testes from each species revealed eight spermatogenic stages. Male coal skinks produced sperm by late February, at least one month before male five-lined skinks. Height of the testicular cycle (maximum sperm production-stage 6 = spermiogenesis) in E. a. pluvialis occurred in March and early April, whereas in E. fasciatus, spermiogenesis reached a peak in May. Testicular recrudescence began in late May in E. a. pluvialis and mid-July in E. fasciatus. The reproductive condition of female skinks was determined by counting and measuring enlarged ovarian follicles and oviductal eggs. Female coal skinks contained vitellogenic ovarian follicles starting in mid-March; vitellogenic ova reached their maximum size by mid-April. Oviductal eggs were recorded from early April to mid-May. Clutch size in E. a. pluvialis averaged 10.5 (5 - 17; n = 27) based on vitellogenic ova and 9.6 (8 - 13; n = 21) based oviductal eggs. No egg clutches of E. a. pluvialis were discovered. In female E. fasciatus, a rapid increase in the rate of vitellogenesis began in late April; yolking ova were last observed in an individual in mid-June. Oviductal eggs were recorded from mid-May to late June; average clutch size based on vitellogenic ova was 10.0 (7 - 15; n = 34), whereas oviductal eggs yielded an average clutch size of 8.4 (6- 12; n = 13). Atresia of ovarian follicles may explain the difference between counts. Clutch size as determined from five nests discovered in June and July was 8.2 (7- 10). Intraspecific synchrony of annual sexual cycles occurs between the sexes of each skink, while only a marginal overlap exists between the two species.

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