Biometric sexual and ontogenetic dimorphism on the marine catfish Genidens genidens (Siluriformes, Ariidae) in a tropical estuary

Abstract

This paper aims to study the ontogenetic sexual dimorphism of Genidens genidens in Guanabara Bay, southeastern coast of Brazil. Altogether 378 specimens were anayzed (233 females and 145 males) with total length ranging from 13.3 to 43.5 cm. Specimens were measured for 12 body measurements, sex was identified and maturity stages were recorded and classified. Pearson’s linear correlation reveled a significant positive correlation between total length and all other body measures, except for base adipose fin, mouth depth and eye depth for immature females. Analyses nested PERMANOVA desing showed significant differences between maturity stages for each sex, between sexes considering or not maturity stages, indicating a variation in morphometric characteristics driven by sexual dimorphism. Differences among all maturity stages were also found, indicating an ontogenetic morphological difference. But immature individuals didn’t differ between sexes indicating that differentiation patterns starts with sexual development. The most important measures differing males and females were related to head characteristics, which appears to be key parameters to evaluate sexual differences. Due to male incubation of fertilized eggs and juvenile individuals <59 mm in their oral cavity, head measures are proposed to be sex dimorphism not related to reproduction, but with post reproductive fase due to ecological and biological needs. [L1]Modificated as suggested by Reviewer E.

Sexual dimorphism and reproductive biology of Cephalocassis borneensis (Siluriformes: Ariidae), a paternal mouth‐brooding fish in the Mekong River

“…To date, sexual dimorphism has been reported in three ariid species of the genus Cathorops (Marceniuk & Betancur‐R., 2008) with similar patterns to C. borneensis . The same sexual dimorphism trend in HL, BD and VFL parameters was also recorded in adults but not immature Guri sea catfish Genidens genidens (Cuvier 1829) (Barbieri et al ., 1992; Paiva et al ., 2015). A convincing explanation for sexual dimorphism in ariid species can be their reproductive tactics, such as egg‐carrying, egg‐laying assistance, and oral cavity extension in males (Paiva et al ., 2015; Rimmer, 1985).…”

“…The same sexual dimorphism trend in HL, BD and VFL parameters was also recorded in adults but not immature Guri sea catfish Genidens genidens (Cuvier 1829) (Barbieri et al ., 1992; Paiva et al ., 2015). A convincing explanation for sexual dimorphism in ariid species can be their reproductive tactics, such as egg‐carrying, egg‐laying assistance, and oral cavity extension in males (Paiva et al ., 2015; Rimmer, 1985). C. borneensis does not show body size difference between adult males and females, which have similar growth patterns ( via L – W relationships).…”

“…Nevertheless, the morphology and reproductive biology of this species are poorly understood. Most previous ariid morphology and reproduction studies have focused on marine species, mainly in Brazil (Barbieri et al ., 1992; Gomes & Araújo, 2004; Maciel et al ., 2018; Paiva et al ., 2015; Pinheiro et al ., 2006; Queiroga et al ., 2012), Mexico (Muro‐Torres & Amezcua, 2011; Segura‐Berttolini & Mendoza‐Carranza, 2013) and Malaysia (Isa et al ., 2012). Thus, this study aims to evaluate and provide crucial information on the morphological, biological and reproductive characteristics of a wild C. borneensis population, which will potentially support future actions to protect and maintain population sizes of this species and reinforce the systematics and taxonomy of the Ariidae.…”

Morphometric analysis of lapillus otoliths in two estuarine bioindicator catfish (Siluriformes, Ariidae) from a marine protected area in Brazil

“…In this study, we intended to analyze whether there are sexual and temporal changes in otolith Morais et al dimensions of the two ariid species C. spixii and G. genidens. Some studies have shown that, although G. genidens does not present evident sexual dimorphism demonstrated by body morphometrics, significant differences are observed, mainly in head and mouth measurements, related to the oropharyngeal incubation of offspring performed by males (Paiva et al, 2015). In addition, studies using otolith measurements of G. genidens found differences between the sexes with respect to growth parameters such as length and age rings (Maciel et al, 2018).…”