Sexual size dimorphism, relative growth and handedness in Liocarcinus depurator and Macropipus tuberculatus (Brachyura: Portunidae) |
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Pere Abelló, Juan P. Pertierra, David G. Reid |
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Some morphometric relationships and biometric aspects are studied in the portunid crabs Liocarcinus depurator and Macropipus tuberculatus: differences in size between the sexes, sex-ratio as a function of size, relative growth of the carapace and chelae, and handedness. Samples were taken on the shelf and upper slope in the northwestern Mediterranean. Males reached larger sizes than females in both species. The sex-ratio did not differ from 1:1 in the smaller sizes; medium sizes were dominated by females, whereas males were more abundant in the larger sizes. No significant differences were found in carapace relative growth between male and female crabs. Males showed a low positive allometry in chela growth. In females, relative chela growth was closer to isometry. The low levels of positive allometry in chelar relative growth are in accordance with the swimming ability shown by most members of the family Portunidae. Both species had allometry levels lower than those shown by strictly benthic species of the family. A mean size at sexual maturity of 24 mm carapace length is estimated for male L. depurator. Sexual dimorphism in chela length is stronger in M. tuberculatus than in L. depurator. Both species are heterochelic, the right chela usually being the crusher, and the left one the cutter. No strong evidence for an increase in reversal of handedness in relation to the size of crabs was found in either sex in either species. |
Keywords: Relative growth, sexual dimorphism, handedness, Brachyura, Liocarcinus depurator, Macropipus tuberculatus, Mediterranean |
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Sci. Mar. 54(2) : 195-202 |
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