Morphometric aspects of the digestive tract of Roeboides xenodon and Orthospinus franciscensis

Abstract

Roeboides xenodon (dentudo) and Orthospinus franciscensis (piaba-facão) are small Teleostei with omnivorous feeding habits. In order to study the morphology of the digestive tract, specimens of O. franciscensis (n = 15) and R. xenodon (n = 16) were collected in the São Francisco River, Três Marias - MG and fixed in 4% formalin. In both species, a short esophagus began in the head and after the transverse septum, remained in the peritoneal cavity up to the first section of the stomach. In R. xenodon, the esophagus showed primary thick folds, narrow and longitudinally arranged, separated by deep grooves and free edges and lines. In O. franciscensis, the esophagus displayed longitudinal primary folds, thick and wide, no deep grooves, but with free edges and few anastomoses. The stomach was of the cecal type in “Y.” The intestines consisted of two parts: a longer and more convoluted anterior part and a short posterior section. The beginning of the hindgut was marked by an abrupt change in the pattern of the mucosa. There was an anal sphincter at the distal end of the digestive tract. The digestive tract of both species is complete and adapted to their carnivorous habits