Rhinobrycon negrensis, Myers, 1944

Baicere-Silva, Clarianna Martins, Ferreira, Katiane M., Malabarba, Luiz R., Benine, Ricardo C. & Quagio-Grassiotto, Irani, 2011, Spermatic characteristics and sperm evolution on the subfamily Stevardiinae (Ostariophysi: Characiformes: Characidae), Neotropical Ichthyology 9 (2), pp. 377-392 : 383

Rhinobrycon negrensis ( Fig. 15 A-E)

In the spermatozoon of Rhinobrycon negrensis , the spherical nucleus measures approximately 1.5  m in diameter. The surrounding strip of cytoplasm has no organelles ( Fig. 15A ). Nuclear rotation toward the flagellar axis was about 50 degrees ( Fig. 15 A-B). Large vesicles are found laterally to the nucleus ( Fig. 15 B-C). The midpiece has a rhomboid shape, measures about 1.1  m in length and contains some mitochondria ( Fig. 15 A-C). The endomembrane system is composed of a few large vesicles ( Fig. 15 B-E).

Figures

Fig. 15. Spermatozoa of Rhinobrycon negrensis. A: Longitudinal section of spermatozoa. Note the position of the nucleus (n) in relation to the flagellar axis and to proximal (p) and distal (d) centrioles, the eccentric position of the double nuclear fossa (double arrow), the midpiece and the cytoplasmic canal (*) containing the initial segment of the flagellum (f). B-C: Longitudinal sections of the midpiece exposing the lateral position of the distal centriole (d), the cytoplasmic canal (*) and the flagellum (f), the distribution of the few elongate mitochondria (m) accumulated in larger portion of the midpiece, few large vesicles peripherally distributed (v). D-E: Cross sections at different levels of the asymmetric midpiece showing the mitochondria (m) and a few vesicles (v). Information on the endomembrane system was not preserved due the specimens of R. negrensis herein analysis have been obtained from ichthyological collections.