Relative growth of the second pereiopod in Macrobrachium olfersi (Wiegmann, 1836) (Decapoda, Palaemonidae)

Abstract

The heterochelous condition of the second pair of pereiopods in both male and female Macrobrachium olfersi from São Sebastião, Brazil, was investigated by means of quantitative analysis. A positive allometric growth of the propodus (length and height) was observed for males and females, either juveniles or adults. The differential growth of both minor and major propodus is already initiated in the juvenile stage and proceeds towards adulthood without a distinct critical moult, and nally takes its full development in large adults, being especially more pronounced in large males. The differential growth of the larger second claw eventually leads to the development of the well known sexual dimorphism that characterizes this species. No preferential handedness, i.e., left or right, was discernible in either sex. RÉSUMÉLa condition d'hétérochélie de la seconde paire de péréiopodes chez le mâle et la femelle de Macrobrachium olfersi de São Sebastião, Brésil, a été étudiée par analyse quantitative. Une croissance allométrique positive du propode (longueur et hauteur) a été observée chez les mâles et chez les femelles aussi bien jeunes qu'adultes. La croissance différentielle, à la fois des petits et grands propodes commence déjà au stade juvénile et se poursuit jusqu'au stade adulte sans mue critique distincte et prend son plein développement chez les adultes de grande taille, et de façon plus prononcé chez les grands mâles. La croissance différentielle de la plus grande des secondes pinces conduit nalement au développement du dimorphisme sexuel bien connu qui caractérise cette espèce. Quel que soit le sexe, on ne peut discerner ni droitier, ni gaucher chez les individus.

Populational and reproductive aspects of Southern <i>Macrobrachium acanthurus</i> (Wiegmann, 1836) (Crustacea: Palaemonidae), Brazil

“…For some authors there are signs that environmental characteristics can influence the population dynamics and individuals' sizes (Ammar et al, 2001), and so can the sampling method used. The presence of partially submerged vegetation along the river banks serves as a natural shelter for some species of caridean shrimps (Mossolin & Bueno, 2003;Mortari & NegreirosFransozo, 2007), corroborating the assertion made by Carvalho (1973), that these areas are the optimal place to observe and obtain these animals.…”

Relative growth, sexual dimorphism and morphometric maturity of Trichodactylus fluviatilis (Decapoda: Brachyura: Trichodactylidae) from Santa Terezinha, Bahia, Brazil

“…Sexual dimorphism was determined based on body (CW and 5AB) and claw dimensions of adult specimens (MOSSOLIN & BUENO 2003, BUENO & SHIMIZU 2009). Carapace width of males and females was compared with the non-parametric MannWhitney test because data for both males (W = 0.88, p < 0.001) and females (W = 0.89, p < 0.01) showed a non-normal distribution (ZAR 1996).…”

Studies on the morphometry of Macrobrachium nobilii (Decapoda, Palaemonidae)

“…Allometric or relative growth pattern of various decapod crustaceans has been studied widely (Hartnoll, 1978;Finney and Abele, 1981;Sumpton, 1990;Sarda and Cartes, 1997;Munio et al, 1999), including genus Macrobrachium (Holthuis, 1950;Koshy, 1973;Jayachandran, 1998;Mossolin and Bueno, 2003). Allometric growth is determined by treating one variable (X) as reference or independent dimension and comparing it with another dependent variable (Y) (Snedecor and Cochran, 1967).…”