RESUMO
A study on the relative growth of the crab Acantholobulus schmitti (Rathbun, 1930) (Decapoda, Brachyura, Panopeidae) was performed with allometric techniques. The species is associated with lanterns used for oyster farming at Guaratuba Bay, southern Brazil. Crabs were obtained from five lanterns from March through December 2009. The following morphological characteristics were measured: the carapace width (CW), the height and length of the major cheliped propodus (LPH and LPL), the width of the female abdomen at the base of the 4th somite (AW) and the length of the male gonopod (GL). A total of 1,004 individuals of A. schmitti were measured, of which 451 were males, 323 non-ovigerous females and 230 ovigerous females. The CW of the males varied from 1.87 to 11.86 mm, that of non-ovigerous females from 1.44 to 8.77 mm and that of ovigerous females from 4.09 to 11.12 mm. The plot of LPH against CW showed a mean inflection point at 3.67 mm CW for the males. This result indicated that male crabs are juvenile below this value and adult above it. For the females, the corresponding inflection point occurred at 3.36 mm CW in the plot of AW against CW. These results, CW x LPH and CW x AW, highlight the importance of chelae enlargement at the onset of maturation in males. Similarly, the widening of the abdomen in females is required to accommodate egg clutches during the reproductive period. Heterochely was recorded in both sexes. Right-handed crabs were more frequent than left-handed ones, with percentages of 75.8% in males and 82.7% in females. The population of A. schmitti from Guaratuba Bay becomes sexually mature at an earlier age than A. schmitti from the coast of São Paulo state. The lanterns used in oyster farming furnish a safe habitat in which these crabs can spend their entire benthic life.
Um estudo sobre o crescimento relativo do caranguejo Acantholobulus schmitti (Rathbun, 1930) (Decapoda Brachyura Panopeidae) foi realizado utilizando o método alométrico. A espécie está associada às lanternas de ostras na Baía de Guaratuba, no sul do Brasil. Os caranguejos foram obtidos de cinco lanternas de março a dezembro/2009. Foram obtidas as seguintes dimensões somáticas dos caranguejos: largura da carapaça (CW), altura e comprimento do própodo do maior quelípodo (LPH e LPL), largura do abdômen da fêmea na base do quarto somito (AW) e o comprimento de gonópodo dos machos (GL). Um total de 1.004 indivíduos de A. schmitti foi medido, destes 451 foram machos, 323 fêmeas e 230 fêmeas ovígeras. O CW dos machos variou de 1,87 a 11,86 mm, enquanto para fêmeas não-ovígeras de 1,44 a 8,77 mm e fêmeas ovígeras de 4,09 a 11, 12 mm. O gráfico de dispersão dos pontos empíricos entre CW e LPH mostrou um ponto de inflexão em 3,67 mm CW dentre os machos, indicando que abaixo deste valor, os caranguejos machos ainda são juvenis e acima dele, adultos. Para fêmeas, este ponto foi estabelecido em 3,36 mm CW no gráfico de dispersão entre CW e AW. Esses resultados das relações CW x LPH e CW x AW, destacam a importância do alargamento da quela no início da maturação dos machos, enquanto o alargamento do abdômen é uma demanda natural para as fêmeas, a fim de acomodar ovos no período reprodutivo. A heteroquelia ocorreu em ambos os sexos, sendo caranguejos destros mais frequentes do que os canhotos: 75,8% dentre os machos e 82,7% dentre as fêmeas. A população de A. schmitti da Baía de Guaratuba torna-se sexualmente madura mais cedo do que no litoral de São Paulo, e as lanternas de ostreicultura constituem um habitat seguro para estes caranguejos viverem plenamente a sua vida bentônica.
Assuntos
Animais , Braquiúros/anatomia & histologia , Braquiúros/crescimento & desenvolvimento , Distribuição Animal , BrasilRESUMO
A study on the relative growth of the crab Acantholobulus schmitti (Rathbun, 1930) (Decapoda, Brachyura, Panopeidae) was performed with allometric techniques. The species is associated with lanterns used for oyster farming at Guaratuba Bay, southern Brazil. Crabs were obtained from five lanterns from March through December 2009. The following morphological characteristics were measured: the carapace width (CW), the height and length of the major cheliped propodus (LPH and LPL), the width of the female abdomen at the base of the 4th somite (AW) and the length of the male gonopod (GL). A total of 1,004 individuals of A. schmitti were measured, of which 451 were males, 323 non-ovigerous females and 230 ovigerous females. The CW of the males varied from 1.87 to 11.86 mm, that of non-ovigerous females from 1.44 to 8.77 mm and that of ovigerous females from 4.09 to 11.12 mm. The plot of LPH against CW showed a mean inflection point at 3.67 mm CW for the males. This result indicated that male crabs are juvenile below this value and adult above it. For the females, the corresponding inflection point occurred at 3.36 mm CW in the plot of AW against CW. These results, CW x LPH and CW x AW, highlight the importance of chelae enlargement at the onset of maturation in males. Similarly, the widening of the abdomen in females is required to accommodate egg clutches during the reproductive period. Heterochely was recorded in both sexes. Right-handed crabs were more frequent than left-handed ones, with percentages of 75.8% in males and 82.7% in females. The population of A. schmitti from Guaratuba Bay becomes sexually mature at an earlier age than A. schmitti from the coast of São Paulo state. The lanterns used in oyster farming furnish a safe habitat in which these crabs can spend their entire benthic life.(AU)
Um estudo sobre o crescimento relativo do caranguejo Acantholobulus schmitti (Rathbun, 1930) (Decapoda Brachyura Panopeidae) foi realizado utilizando o método alométrico. A espécie está associada às lanternas de ostras na Baía de Guaratuba, no sul do Brasil. Os caranguejos foram obtidos de cinco lanternas de março a dezembro/2009. Foram obtidas as seguintes dimensões somáticas dos caranguejos: largura da carapaça (CW), altura e comprimento do própodo do maior quelípodo (LPH e LPL), largura do abdômen da fêmea na base do quarto somito (AW) e o comprimento de gonópodo dos machos (GL). Um total de 1.004 indivíduos de A. schmitti foi medido, destes 451 foram machos, 323 fêmeas e 230 fêmeas ovígeras. O CW dos machos variou de 1,87 a 11,86 mm, enquanto para fêmeas não-ovígeras de 1,44 a 8,77 mm e fêmeas ovígeras de 4,09 a 11, 12 mm. O gráfico de dispersão dos pontos empíricos entre CW e LPH mostrou um ponto de inflexão em 3,67 mm CW dentre os machos, indicando que abaixo deste valor, os caranguejos machos ainda são juvenis e acima dele, adultos. Para fêmeas, este ponto foi estabelecido em 3,36 mm CW no gráfico de dispersão entre CW e AW. Esses resultados das relações CW x LPH e CW x AW, destacam a importância do alargamento da quela no início da maturação dos machos, enquanto o alargamento do abdômen é uma demanda natural para as fêmeas, a fim de acomodar ovos no período reprodutivo. A heteroquelia ocorreu em ambos os sexos, sendo caranguejos destros mais frequentes do que os canhotos: 75,8% dentre os machos e 82,7% dentre as fêmeas. A população de A. schmitti da Baía de Guaratuba torna-se sexualmente madura mais cedo do que no litoral de São Paulo, e as lanternas de ostreicultura constituem um habitat seguro para estes caranguejos viverem plenamente a sua vida bentônica.(AU)
Assuntos
Animais , Braquiúros/crescimento & desenvolvimento , Braquiúros/anatomia & histologia , Distribuição Animal , BrasilRESUMO
A study on the relative growth of the crab Acantholobulus schmitti (Rathbun, 1930) (Decapoda, Brachyura, Panopeidae) was performed with allometric techniques. The species is associated with lanterns used for oyster farming at Guaratuba Bay, southern Brazil. Crabs were obtained from five lanterns from March through December 2009. The following morphological characteristics were measured: the carapace width (CW), the height and length of the major cheliped propodus (LPH and LPL), the width of the female abdomen at the base of the 4th somite (AW) and the length of the male gonopod (GL). A total of 1,004 individuals of A. schmitti were measured, of which 451 were males, 323 non-ovigerous females and 230 ovigerous females. The CW of the males varied from 1.87 to 11.86 mm, that of non-ovigerous females from 1.44 to 8.77 mm and that of ovigerous females from 4.09 to 11.12 mm. The plot of LPH against CW showed a mean inflection point at 3.67 mm CW for the males. This result indicated that male crabs are juvenile below this value and adult above it. For the females, the corresponding inflection point occurred at 3.36 mm CW in the plot of AW against CW. These results, CW x LPH and CW x AW, highlight the importance of chelae enlargement at the onset of maturation in males. Similarly, the widening of the abdomen in females is required to accommodate egg clutches during the reproductive period. Heterochely was recorded in both sexes. Right-handed crabs were more frequent than left-handed ones, with percentages of 75.8% in males and 82.7% in females. The population of A. schmitti from Guaratuba Bay becomes sexually mature at an earlier age than A. schmitti from the coast of São Paulo state. The lanterns used in oyster farming furnish a safe habitat in which these crabs can spend their entire benthic life.