Shape and size variations of Aegla uruguayana (Anomura, Aeglidae) under laboratory conditions: a geometric morphometric approach to the growth / Variaciones de forma y tamaño de Aegla uruguayana (Anomura, Aeglidae): una aproximación desde la morfometría geométrica al crecimiento

Los estudios de crecimiento en crustáceos típicamente utilizan análisis modal en lugar de focalizarse en el crecimiento individual de los organismos. En el presente trabajo, utilizamos morfometría geométrica para determinar cómo varia la forma y el tamaño a lo largo de la vida del cangrejo de agua dulce, Aegla uruguayana Schmitt, 1942. Un total de 66 individuos, en diferentes etapas del ciclo de vida, se examinaron diariamente, registrándose la presencia de exuvias. Imágenes digitales de cada muda fueron obtenidas de la región dorsal del cefalotórax y se utilizaron para registrar las configuraciones de landmarks. El incremento por muda y el período de intermuda se estimaron para cada cangrejo. Diferencias de forma entre tamaños (alometría) y sexos (dimorfismo sexual; SD) se observaron. Se registró la presencia de alometría entre los especímenes; sin embargo, el SD no fue estadísticamente significativo respecto del tamaño. El período intermuda aumentó de manera directamente proporcional al tamaño, pero la frecuencia de muda fue similar entre los sexos. Durante la ontogenia, los juveniles presentaron rostro corto y romo, frente robusta, y ancho del cefalotórax estrecho. Los adultos presentaron la región anterior y posterior del cefalotórax bien definido en relación con los juveniles. El rostro fue largo y estilizado y la frente estrecha. Los métodos de morfometría geométrica fueron muy efectivos para el análisis del crecimiento individual en aéglidos y permitieron evitar la manipulación excesiva de los individuos a través del análisis de las mudas(AU)

Crustacean growth studies typically use modal analysis rather than focusing on the growth of individuals. In the present work, we use geometric morphometrics to determine how organism shape and size varies during the life of the freshwater crab, Aegla uruguayana Schmitt, 1942. A total of 66 individuals from diverse life cycle stages were examined daily and each exuvia was recorded. Digital images of the dorsal region of the cephalothorax were obtained for each exuvia and were subsequently used to record landmark configurations. Moult increment and intermoult period were estimated for each crab. Differences in shape between crabs of different sizes (allometry) and sexes (sexual dimorphism; SD) were observed. Allometry was registered among specimens; however, SD was not statistically significant between crabs of a given size. The intermoult period increased as size increased, but the moult frequency was similar between the sexes. Regarding ontogeny, juveniles had short and blunt rostrum, robust forehead region, and narrow cephalothorax. Unlike juveniles crabs, adults presented a well-defined anterior and posterior cephalothorax region. The rostrum was long and stylised and the forehead narrow. Geometric morphometric methods were highly effective for the analysis of aeglid-individual- growth and avoided excessive handling of individuals through exuvia analysis(AU)

Shape and size variations of Aegla uruguayana (Anomura, Aeglidae) under laboratory conditions: a geometric morphometric approach to the growth / Variaciones de forma y tamaño de Aegla uruguayana (Anomura, Aeglidae): una aproximación desde la morfometría geométrica al crecimiento

Los estudios de crecimiento en crustáceos típicamente utilizan análisis modal en lugar de focalizarse en el crecimiento individual de los organismos. En el presente trabajo, utilizamos morfometría geométrica para determinar cómo varia la forma y el tamaño a lo largo de la vida del cangrejo de agua dulce, Aegla uruguayana Schmitt, 1942. Un total de 66 individuos, en diferentes etapas del ciclo de vida, se examinaron diariamente, registrándose la presencia de exuvias. Imágenes digitales de cada muda fueron obtenidas de la región dorsal del cefalotórax y se utilizaron para registrar las configuraciones de landmarks. El incremento por muda y el período de intermuda se estimaron para cada cangrejo. Diferencias de forma entre tamaños (alometría) y sexos (dimorfismo sexual; SD) se observaron. Se registró la presencia de alometría entre los especímenes; sin embargo, el SD no fue estadísticamente significativo respecto del tamaño. El período intermuda aumentó de manera directamente proporcional al tamaño, pero la frecuencia de muda fue similar entre los sexos. Durante la ontogenia, los juveniles presentaron rostro corto y romo, frente robusta, y ancho del cefalotórax estrecho. Los adultos presentaron la región anterior y posterior del cefalotórax bien definido en relación con los juveniles. El rostro fue largo y estilizado y la frente estrecha. Los métodos de morfometría geométrica fueron muy efectivos para el análisis del crecimiento individual en aéglidos y permitieron evitar la manipulación excesiva de los individuos a través del análisis de las mudas

Crustacean growth studies typically use modal analysis rather than focusing on the growth of individuals. In the present work, we use geometric morphometrics to determine how organism shape and size varies during the life of the freshwater crab, Aegla uruguayana Schmitt, 1942. A total of 66 individuals from diverse life cycle stages were examined daily and each exuvia was recorded. Digital images of the dorsal region of the cephalothorax were obtained for each exuvia and were subsequently used to record landmark configurations. Moult increment and intermoult period were estimated for each crab. Differences in shape between crabs of different sizes (allometry) and sexes (sexual dimorphism; SD) were observed. Allometry was registered among specimens; however, SD was not statistically significant between crabs of a given size. The intermoult period increased as size increased, but the moult frequency was similar between the sexes. Regarding ontogeny, juveniles had short and blunt rostrum, robust forehead region, and narrow cephalothorax. Unlike juveniles crabs, adults presented a well-defined anterior and posterior cephalothorax region. The rostrum was long and stylised and the forehead narrow. Geometric morphometric methods were highly effective for the analysis of aeglid-individual- growth and avoided excessive handling of individuals through exuvia analysis

Evaluación de palaemonetes argentinus (Decapoda, Natantia) en el control biológico de larvas de Culex pipiens (Diptera, Culicidae) en condiciones de laboratorio

The predator-prey relationship of Palaemonetes argentinus Nobili, 1901 and Culex pipiens s.l. larvae was studied under laboratory conditions. The prawns were separated in two groups, isolated and grouped ones. Mosquitoe larvae were offered to prawns in two forms, limited and unlimited offer to both groups. In the first analysis, values of predation did not differ significantly between males and females of P. argentinus. Predation in 24 h was 14,9 ± 4,2 larvae/prawn. A reduction of predation was observed with unlimited offer for the same hour, during all the experiment. Predation with unlimited offer was higher on the first day than on the second, but returned to high values on the third day, for both groups. In the grouped experiment, predation with limited offer was total on the first days, decreasing to the last day. As a result, P. argentinus was considered an efficient predator of C. pipiens s.l. larvae under laboratory conditions.

Evaluación de palaemonetes argentinus (Decapoda, Natantia) en el control biológico de larvas de Culex pipiens (Diptera, Culicidae) en condiciones de laboratorio

The predator-prey relationship of Palaemonetes argentinus Nobili, 1901 and Culex pipiens s.l. larvae was studied under laboratory conditions. The prawns were separated in two groups, isolated and grouped ones. Mosquitoe larvae were offered to prawns in two forms, limited and unlimited offer to both groups. In the first analysis, values of predation did not differ significantly between males and females of P. argentinus. Predation in 24 h was 14,9 ± 4,2 larvae/prawn. A reduction of predation was observed with unlimited offer for the same hour, during all the experiment. Predation with unlimited offer was higher on the first day than on the second, but returned to high values on the third day, for both groups. In the grouped experiment, predation with limited offer was total on the first days, decreasing to the last day. As a result, P. argentinus was considered an efficient predator of C. pipiens s.l. larvae under laboratory conditions.

Evaluación de palaemonetes argentinus (Decapoda, Natantia) en el control biológico de larvas de Culex pipiens (Diptera, Culicidae) en condiciones de laboratorio

The predator-prey relationship of Palaemonetes argentinus Nobili, 1901 and Culex pipiens s.l. larvae was studied under laboratory conditions. The prawns were separated in two groups, isolated and grouped ones. Mosquitoe larvae were offered to prawns in two forms, limited and unlimited offer to both groups. In the first analysis, values of predation did not differ significantly between males and females of P. argentinus. Predation in 24 h was 14,9 ± 4,2 larvae/prawn. A reduction of predation was observed with unlimited offer for the same hour, during all the experiment. Predation with unlimited offer was higher on the first day than on the second, but returned to high values on the third day, for both groups. In the grouped experiment, predation with limited offer was total on the first days, decreasing to the last day. As a result, P. argentinus was considered an efficient predator of C. pipiens s.l. larvae under laboratory conditions.