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 Hemibrycon surinamensis ( Fig. 10 A-F) In the spermatozoon of Hemibrycon surinamensis the ovoid nucleus measures 1.52  m in the longitudinal axis and 1.2  m in the transverse axis. The surrounding strip of cytoplasm has no organelles ( Fig. 10A ). Nuclear rotation toward the flagellar axis was about 95 degrees ( Fig.10A ).The midpiece has a conical shape, measures about 0.9  m in length and contains some slightly elongatemitochondria( Fig.10A ).Apossibleendomembranesystem seems to be composed of a clump of small vesicles ( Fig.10 B-F).