Relative growth and morphological sexual maturity size of the freshwater crab Trichodactylus borellianus (Crustacea, Decapoda, Trichodactylidae) in the Middle Paraná River, Argentina

By

Williner, Verónica
Torres, María Victoria
Carvalho, Débora de Azevedo
König, Natalia

Type

Article

Date of Publication

2014

Original Publication

ZooKeys

Volume

457

Pages

159-170

Subjects

cephalothorax width , Chelipeds , Growth , pleopods , regression model , Reproduction

Contributed by

Pensoft Publishers

Language

English

Published by

Sofia, Bulgaria Pensoft Publishers

Identifiers

DOI: https://doi.org/10.3897/zookeys.457.6821

 

Abstract

The relative growth of a number of morphological dimensions of the South American freshwater crab Trichodactylus borellianus (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 T. borellianus was found to be similar to that recorded for other species of the family Trichodactylidae.