ウネレイシダマシとシマレイシダマシの歯舌の性的二形
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概要
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The radulae of Cronia margariticola (Broderip) and Morula musiva (Kiener) were examined on the specimens collected from southern Japanese waters. Although the radulae of these species have been already reported on by some authors, the present study reveals existence of sexual dimorphism and continuous changes with age in radula of both species. The length of radular ribbons and the breadth of rachidian teeth relative to shell length increase with growth. In the adult stage larger than 16mm in shell length, the rachidian and lateral teeth of males of these species were usually larger and grew more rapidly than those of females. Thus, the male radular characters may represent the secondary sexual characters. The actual number of radular rows is not sexually dimorphic and does not reveal differences between young and adult specimens. The rachidian teeth exhibit remarkable changes in shape as well as size with growth. As a rule, the rachidian teeth found in the young stage are of a complicated form with marked exterior (outer) denticles and marked marginal humps or cusps, and by gradual transformation, change to the simple form found in the adult stage. The rachidian teeth of fully grown males are extremely simplified due to such changes as well as sexual dimorphism. Investigation into previously published works combined with the known influence of sexual dimorphism, it can be shown that the rachidian teeth of Morula are characterized by atrophied exterior denticles and marginal cusps, which are intermediate in radular characters between Cronia and Thais.
- 日本貝類学会の論文
- 1984-12-31
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