Reproductive seasonality of Monetaria annulus (Linnaeus, 1758) (Mollusca: Gastropoda: Cypraeidae) in a temperate area
In: Molluscan Research. Malacological Society of Australasia: Sydney. ISSN 1323-5818; e-ISSN 1448-6067, meer
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| Author keywords |
histological analysis, reproductive stages, sex ratio, sexual dimorphism |
| Auteurs | | Top |
- Villamor, S.
- Yamamoto, T.
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| Abstract |
The objectives of this study are: (1) to detect the developmental stages in the gonads of Monetaria annulus through histological analysis; (2) to determine the spawning season of this species in a temperate area through seasonal changes in the proportion of each gonadal stage; and (3) to analyse the sex ratio and sexual dimorphism through gonad histology. Samples were obtained randomly from an intertidal rocky shore in Hanazesaki, Ibusuki, Kagoshima Prefecture, Japan (31 11′30.10″N, 130 30′29.70″E) every 2 months from February 2011 to June 2012. Reproductive stages were identified and classified as Stage 1 (initial maturity), Stage 2 (peak maturity) and Stage 3 (spawned). Stage 2 males and females were found during more than half of the year, but their proportion varied seasonally. Although the reproductive peak was slightly different year by year in the temperate area, M. annulus seemed to have two reproductive seasons, in spring and from late summer to winter. The sex ratio was biased towards females, but it was not statistically significant. The mean shell length of females was significantly larger than that of males, though they overlapped widely. |
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