Spermatic characteristics and sperm evolution on the subfamily Stevardiinae (Ostariophysi: Characiformes: Characidae) Author Baicere-Silva, Clarianna Martins Author Ferreira, Katiane M. Author Malabarba, Luiz R. Author Benine, Ricardo C. Author Quagio-Grassiotto, Irani text Neotropical Ichthyology 2011 2011-05-27 9 2 377 392 http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-62252011000200016&lng=en&tlng=en journal article 10.1590/S1679-62252011005000014 1982-0224 5422771 Piabina anhembi ( Fig. 13 A-K) In the spermatozoon of Piabina anhembi the ovoid nucleus measures 1.94  m in the longitudinal axis and 1.64  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  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).