Piabina anhembi (Fig. 13 A-K)

In the spermatozoon of Piabina anhembi the ovoid nucleus measures 1.94 µ m in the longitudinal axis and 1.64 µ m in the transverse axis. The surrounding strip of cytoplasm has no organelles (Fig. 13A). Nuclear rotation toward the flagellar axis was about 80 degrees (Fig. 13A). The midpiece has a conical shape, measures about 1.13 µ m in length and contains some large and slightly elongated mitochondria (Fig. 13A). The endomembrane system is composed of vesicles with different sizes. The smaller are sparse, whereas the larger ones are connected to one another and to the plasma membrane (Fig. 13 B-K).