Pimelodus britskii, Garavello & Shibatta, 2007

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 britskii . The diploid number of this species was also 56 chromosomes (24 m + 18 sm + 8 st + 6 a) ( Fig. 1b ). The AgNORs were located in the terminal region of the long arm of a pair of subtelocentric chromosomes 23 ( Fig. 1b , box). C-banding revealed the existence of pale heterochromatin in the region of the telomeres of some chromosomes, with more conspicuous heterochromatin being found in the telomeric region of the long arm (pairs 3, 6 and 23), in the subterminal region of the long arm (pair 15), pericentromeric region of the short arm (pair 2) and in long arm in pair 17 ( Fig. 2b ). The 18S rDNA was located on the subtelocentric chromosome pair (23), which corresponds to the AgNORs, while the 5S rDNA was found at multiple sites, located in the pericentromeric region of the long arm of pair 17 and terminal region of the long arm of pairs 23 and 28 ( Fig. 3b ).

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.