Fig. 3 in Markiana nigripinnis (Perugia, 1891) as a putative member of the subfamily Stevardiinae (Characiformes: Characidae): spermatic evidence

Fig. 3. Spermatozoa of Markiana nigripinnis LBP 4935. A: Longitudinal section of spermatozoon. Note the lateral position and pattern of chromatin condensation in the nucleus (n), the position of the double nuclear fossa (double arrows), the midpiece and the cytoplasmic canal (*) containing the initial segment of the flagellum (f). A-Inset: Detail of the position, form and depth of the nuclear fossa, and the position of the proximal (p) and distal (d) centrioles to one another and to the nuclear fossa. B: Oblique section of spermatozoa. Note the alveolar aspect of the tubular vesicular system C-K: Cross sections at different levels of the stongly asymmetric midpiece, from the base of the nucleus (n) to the midpiece end. Note the lateral position of the centriole (c), cytoplasmic canal (*) and of the flagellum (f), the distribution of a few elongate and ramified mitochondria (m) accumulated in larger side of the midpiece, tubular vesicular system (v). L: Cross section of the flagellum with the classic axoneme (a).