Two culture experiments from 1995 until 1997 were carried out with larvae obtained from gravid females of Cryphiops caementarius (Molina 1782), to define a methodology in order to produce juvenile using controlled conditions of water temperature, salinity and feeding. Time in culture of larval development and the survival rate were determined. Two distinct types of culture systems were studied. Both systems incorporated a standard alimentation using nauplius of Artemia sp. plus microalgae; however the second system included, in addition, a supplement of fish and chiken eggs. The decrease in survival rate in both cultures systems was related to morphological changes in each stage of development. Juveniles were obtained after 98 days of culture with the first culture system, whereas in the second culture system, the time to reach the first juvenile stage was 62 days. In addition, an increase in the values for metamorphosis synchronism induced a good amount of metamorphosed animals (juveniles) during the time involved in this study.

Con larvas obtenidas de hembras grávidas de Cryphiops caementarius (Molina 1782), se realizó dos experiencias de cultivo entre 1995 y 1997. Estas experiencias fueron diseñadas con el propósito de definir una metodología que permitiera producir juveniles de la especie, utilizando condiciones controladas de temperatura, salinidad y alimentación. Durante este estudio se determinó el desarrollo larval, su duración y la tasa de supervivencia. La disminución en la tasa de supervivencia en ambos cultivos fue coincidente con los cambios morfológicos en cada estado de desarrollo. Durante el primer cultivo, el estado de primer juvenil fue alcanzado a los 98 días. Durante la segunda experiencia, el tiempo empleado en la obtención del primer estado de juvenil fue de 62 días. Durante ésta, se utilizó un suplemento alimenticio consistente en pescado y huevos de gallina. Otro de los resultados importantes logrados fue el aumento en los valores de sincronía en la metamorfosis, lo cual permitió obtener una importante cantidad de animales metamorfoseados (juveniles) durante el tiempo involucrado en el estudio.

Riggia acuticaudata sp. nov. is described on the basis of 10 female specimens recovered from the body cavity of the freshwater catfish, Ancistrus sp. The fish were caught in a stream called the Corrego Piraputanga, a tributary of the Paraguai River. The new species differs from the others in the genus by being smaller and less convex and by having a pleotelson that tapers abruptly rather than being the same width throughout. Also, the pereopods and dactyls are much smaller, the maxillule has two terminal and three subterminal spines and the first two pleopods are elongate and acute. Additionally, R. acuticaudata sp. nov. is from a different Order of fish host and a new geographic area.