Gross morphology and histology of the intestine of Aspidoras gabrieli, an endemic catfish of the lower Tocantins River basin

We describe morphological features of the digestive tract of the endemic callichthyid Aspidoras gabrieli in Serra dos Carajás, southeastern Amazon. The species displays a tubular digestive tract divided into the digestive and aerial gut, separated by a mild constriction. The aerial gut is longer, but with thinner walls than the digestive gut. Microscopically, the aerial gut exhibits several traits of respiratory tissues, such as pseudostratified cells in the mucosa and goblet cells. These traits may allow A. gabrieli to air-breath and thus inhabit hypoxic environments.