title: Relative growth and morphological sexual maturity size of the freshwater crab Trichodactylusborellianus (Crustacea, Decapoda, Trichodactylidae) in the Middle Paraná River, Argentina.
abstract: The relative growth of a number of morphological dimensions of the South American freshwater crab Trichodactylusborellianus (Trichodactylidae) were compared and related to sexual dimorphism. Crabs were collected from ponds in the Middle Paraná River in Argentina. A regression model with segmented relationship was used to test for relative growth between these measurements where breakpoints infer the body size at which crabs reach sexual maturity. In both sexes the carapace width and the length, height, and thickness of the right and left chelae were measured, as well as the male pleopod length and the female abdomen width. All of these measurements were found to show positive allometry with the exception of the male pleopod length and the left chelae, which did not show a breakpoint. In females the breakpoint for the abdomen width inferred a morphological sexual maturity at carapace width 6.9 mm. In males the break point for the pleopod length was at carapace width 6.6 mm, with that for the chelae measurements was between carapace widths 6.4 and 6.9 mm. The relative growth pattern in Trichodactylusborellianus was found to be similar to that recorded for other species of the family Trichodactylidae.
authors.affiliation: Instituto Nacional de Limnología (CONICET-UNL). Ciudad Universitaria Paraje El pozo s/n. Santa Fe. Argentina ; Facultad de Humanidades y Ciencias, (UNL). Ciudad Universitaria Paraje El pozo s/n. Santa Fe. Argentina.
authors.forename: Verónica
authors.initials: V
authors.lastname: Williner
authors.affiliation: Instituto Nacional de Limnología (CONICET-UNL). Ciudad Universitaria Paraje El pozo s/n. Santa Fe. Argentina.
authors.forename: María Victoria
authors.initials: MV
authors.lastname: Torres
authors.affiliation: Facultad de Humanidades y Ciencias, (UNL). Ciudad Universitaria Paraje El pozo s/n. Santa Fe. Argentina.
authors.forename: Débora Azevedo
authors.initials: DA
authors.lastname: Carvalho
authors.affiliation: Facultad de Humanidades y Ciencias, (UNL). Ciudad Universitaria Paraje El pozo s/n. Santa Fe. Argentina.
authors.forename: Natalia
authors.initials: N
authors.lastname: König
keywords: Chelipeds; cephalothorax width; growth; pleopods; regression model; reproduction