Maturidade sexual morfológica de Aegla platensis (Crustacea, Decapoda, Anomura) no Lajeado Bonito, norte do estado do Rio Grande do Sul, Brasil

Abstract

O tamanho da primeira maturação sexual (TPM) em Aegla platensis Schmitt, 1942 foi estimado através das mudanças nas proporções de dimensões corporais dos animais. Para isso, foram realizadas coletas mensais, de julho de 2007 a junho de 2008 no Lajeado Bonito (27º25'27''S, 53º24'39''W), um tributário de primeira ordem do Rio da Várzea, município de Frederico Westphalen, Rio Grande do Sul. Foram utilizados 437 machos com comprimento de cefalotórax (CC) variando de 6,00 mm a 31,75 mm e 368 fêmeas, com tamanhos entre 6,08 mm e 27,92 mm de CC. As seguintes dimensões corporais foram mensuradas em todos os indivíduos coletados: comprimento do cefalotórax (CC), largura do abdome (LA), comprimento do própodo do quelípodo direito (CPD) e comprimento do própodo do quelípodo esquerdo (CPE). Após o registro dessas medidas, os animais foram devolvidos ao mesmo local de captura. As análises de maturidade sexual morfológica foram realizadas com auxílio do software Mature 2, nas quais foram utilizadas as medidas de CC, considerada como variável independente e relacionada com as demais dimensões. As relações que melhor se ajustaram para estas análises, em machos, foram CPD x CC (TPM: CC=18,2 mm) e CPE x CC (TPM: CC=20,1 mm) e LA x CC (TPM: CC=16,5 mm) nas fêmeas.

Allometric growth, sexual maturity and reproductive cycle of Aegla castro (Decapoda: Anomura: Aeglidae) from Itatinga, state of São Paulo, southeastern Brazil

“…Aegla is typically heterochelous, with handedness of the more robust chela predominantly skewed to the left side of the pair (Schmitt, 1942;Bahamonde and López, 1961;López, 1965;Rodrigues and Hebling, 1978;Viau et al, 2006;Bueno and Shimizu, 2009;Oliveira and Santos, 2011). In these freshwater anomurans, heterochely is equally observed in the population regardless of sex, except for a single case of homochely reported in males and females of Aegla leptodactyla Rossi, 1977 (Noro andBuckup, 2003).…”

“…Although pleon dimensions have frequently been used as dependent variable (Colpo et al, 2005;Viau et al, 2006;Oliveira and Santos, 2011;Trevisan and Santos, 2012;Copatti et al, 2015) in similar studies regarding female aeglids, Bueno and Shimizu (2009) have shown that the use of chelae dimensions as dependent variables in allometric growth analysis can be equally informative either in males or females and can provide very consistent and precise results, as long as bivariate dataset (selected dependent variable vs. independent variable) are grouped according to major and minor chelae criterion. This procedure is recommended so as to avoid the introduction of possible biased data whenever a predominantly-sided handedness -while still exhibiting proportion of individuals with reversed handedness -is clearly detected in a heterochelous population should the left-and-right chelae criterion be chosen instead (Bueno and Shimizu, 2009).…”

“…4 is an update of Tab. 3 originally provided by Oliveira and Santos (2011) and includes the currently available data on size at onset of morphometric maturity and its proportion in relation to the size of the largest sampled individual of Aegla species. Although the absolute sizes vary considerably among species, the range of variation in proportion is fairly narrow (0.38-0.60), indicating that aeglids tend to attain morphometric maturity by the time they are approximately half as large as the maximum size they reach.…”

“…The former is associated with the puberty molt and marks the transition from the juvenile into the adult phase, whereas the latter refers to sexually matured individuals that successfully take part in the reproductive process (see López-Greco and Rodríguez, 1999 for review on sexual maturity in decapods). Allometric growth analysis has been often employed in determining the average size at the onset of morphometric maturity of aeglids species (Colpo et al, 2005;Viau et al, 2006;Bueno and Shimizu, 2009;Oliveira and Santos, 2011;Trevisan and Santos, 2012;Copatti et al, 2015).…”

Sexual dimorphism in Aegla marginata (Decapoda: Anomura)

“…This assumption is based on previous studies of relative growth and size at the onset of morphometric maturity in aeglids. These studies include morphological analyses and analyses involving the geometric morphometric of the carapace (Giri and Collins, 2004;Colpo et al, 2005;Viau et al, 2006;Collins et al, 2008;Giri and Loy, 2008;Oliveira and Santos, 2011;Hepp et al, 2012;Trevisan and Santos, 2012). The enlargement of the posterior carapace is a sexually related process that occurs specifically among aeglids.…”