Absolute and allometric relationships between internal morphology and body mass in the adult collared peccary, Tayassu tajacu (Tayassuidae).

Selected morphological features of 8 adult male and 8 adult female collared peccaries (Tayassu tajacu) shot from southern Texas during March 1983 are described. A total of 16 adult peccaries with an average body mass of 18.68 +/- 0.61 (SE) Kg was examined. Significant differences between males and females were observed for absolute and relative mass of liver and lungs, and relative heart mass. These visceral organs were heavier among females than males. Significant sex effects were also found for absolute and relative mass of the dorsal scent gland. The dorsal scent gland contributed twice as much to total body mass in males as in females. No sexual dimorphisms of the gastrointestinal tract were noted. Females had a significantly greater portion of total visceral fat deposited around the kidneys than did males. Relative mass of the mandible was significantly greater in males than in females. Adult males had extremely large accessory sex glands. The bulbourethral and seminal vesicle glands comprised 0.27 per cent of the total body mass. Allometric growth coefficients (b) varied among the various organs and glands examined, ranging from below (eyes, b = 0.34) to well above (seminal vesicles, b = 1.87) unity. Growth coefficients of lungs, kidneys, pituitary gland, and thyroid gland during adulthood greatly exceeded respective values in developing nurslings.