Spermatozoa of Eigenmannia trilineata - Sternopygidae The spermatozoa of Egenmannia trilineata are comprised of a spherical head (Fig. 3A) containing an ovoid nucleus (Fig. 1B), a distinct midpiece (Fig. 3 B-E), and single flagellum (Fig. 3 A-B). Nuclear length measured approximately 1.3 µm and width 1.3 µm. The nucleus contains masses of electron-dense flocculent chromatin in a lighter matrix (Fig. 3 B-E). Nuclear rotation takes place during spermiogenesis. The proximal centriole is anterior and perpendicular to the distal centriole and both centrioles are contained within a nuclear fossa (Fig. 3B). It was not possible to definitively identify a cytoplasmic collar in the region immediately posterior to the nucleus; however, more posteriorly a collar is lacking. The midpiece contains several elongate mitochondria (Fig. 3 B-D-E) and relatively few vesicles (Fig. 3 D-E). The flagellum has the usual 9 + 2 microtubular arrangement with no intratubular differentiation (Fig. 3 C-D). Along most of its length the flagellum has a pair of lateral projections or fins (Fig. 3C).

Published as part of Giora, Júlia & Burns, John R., 2011, Sperm ultrastructure in three different families of weakly electric fishes (Teleostei: Gymnotiformes), pp. 881-888 in Neotropical Ichthyology 9 (4) on page 884, DOI: 10.1590/S1679-62252011005000047, http://zenodo.org/record/5756622