Ontogeny of the brain of Microglanis garavelloi Shibatta and Benine 2005 (Teleostei: Siluriformes: Pseudopimelodidae)

The gross brain morphology and the peripheral olfactory organ of Microglanis garavelloi are described throughout development, and the relationship of these organs to the general behaviour of the species is discussed. During the development, the main brain subdivisions undergo a series of morphological changes keeping a relatively constant volume increase. However, we observed different growth rates in the brains of males and females when these were compared. During the maturation process, a series of hormonal events result in the development of some secondary sexual traits in the brain of male specimens, like faster growth rate of brain areas linked to motor control, olfactory and visual responses. The number of olfactory‐organ lamellae increases continuously in both males and females, during their maturation period. These results suggest that changes may be caused by cognitive demands that this species is exposed to throughout its lifespan. The gross morphological arrangement of the central nervous system indicates shared patterns with other members of the family Pseudopimelodidae. Sexual dimorphism in growth rate for each brain subdivision of Microglanis garavelloi. The present manuscript addressed the poorly understood brain development of neotropical catfishes using M. garavelloi as a model. This study demonstrated different rates of growth between males and females and an increased number of olfactory organ lamellae during maturation period. The patterns observed herein can be useful for some future studies and will be important to understand the evolution of central nervous system in siluriform groups.