Reproductive biology of Pseudocorynopoma doriai (Pisces: Characidae) in the High Basin of the Samborombón River, province of Buenos Aires, Argentina

The reproductive period of the Glandulocaudine Pseudocorynopoma doriai was determined by the analysis of 240 females, 90 males and 138 immature individuals collected monthly in the Manantiales and the El Portugués rivers. The reproductive period is seasonal, occurring from late winter to mid‐summer, with another reproductive peak of smaller magnitude in early autumn. The mean monthly GSI in males has a significant correlation with rainfall. Other analyzed environmental variables, including temperature, photoperiod, pH and conductivity, did not show a correlation with the mean monthly GSI in females and males. First maturity in females was reached within the 42–43 mm standard length class. Like other Glandulocaudines from southern Brazil, males initiate sexual maturation before females, which implies an adaptive advantage in that this would enable females to spawn under optimal environmental conditions. The mean absolute fecundity was 1286.42 oocytes (SD = 496.9083); the mean relative fecundity was 0.5070 (SD = 0.1333) oocytes by milligram body weight.