Pimelodus absconditus, Azpelicueta, 1995

Girardi, Simone C., Pavanelli, Carla S. & Margarido, Vladimir P., 2018, Contributions to the systematic of Pimelodidae (Osteichthyes, Siluriformes): basic and molecular cytogenetics on seven species of Pimelodus from three Brazilian hydrographic systems, Neotropical Ichthyology 16 (2), pp. 1-16 : 6

Pimelodus absconditus . We found a diploid number of 56 chromosomes (24 m + 18 sm + 8 st + 6 a) ( Fig. 1a ). The AgNORs were located in the terminal region of the long arm of a pair of subtelocentric chromosomes (24) ( Fig. 1a , box). C-banding revealed the existence of pale heterochromatin in the most of the centromeres of chromosomes, with some pairs showing heterochromatin conspicuous in the telomeric region of the short arm (pars 17 and 18) and the long arm (pair 24), in both telomeres (pairs 8 and 20), in the pericentromeric region of the long arm of pair 18 and in subterminal region of the long arm of pair 17 ( Fig. 2a ). The 18S rDNA was located on the subtelocentric chromosome pair (24), which corresponds to the AgNORs, while the 5S rDNA was found in the pericentromeric region of the long arm of pair 18 ( Fig. 3a ).

Figures

Fig. 1. Karyotypesarranged fromGiemsa-stained chromosomes.a. Pimelodusabsconditus; b. Pimelodusbritskii; c. Pimelodus maculatus; d. Pimelodus microstoma; e. Pimelodus mysteriosus; f. Pimelodus ortmanni; g. Pimelodus paranaensis. Pairs of the AgNORs and B chromosomes are in the boxes. Scales bar = 10 μm.

Fig.2. Karyotypesarranged from C-banded chromosomes.a. Pimelodusabsconditus; b. Pimelodus britskii; c. Pimelodus maculatus; d. Pimelodus microstoma; e. Pimelodus mysteriosus; f. Pimelodus ortmanni; g. Pimelodus paranaensis. B chromosomes in the boxes. Scales bar = 10 μm.

Fig. 3. Karyotypes after FISH with 5S rDNA probes (red) and 18S rDNA probe (green). a. Pimelodus absconditus; b. Pimelodus britskii; c. Pimelodus maculatus; d. Pimelodus microstoma; e. Pimelodus mysteriosus; f. Pimelodus ortmanni; g. Pimelodus paranaensis. Scales bar = 10 μm.