Close karyotypical relationship between two species of marine angelfishes from South Atlantic: Pomacanthus arcuatus and P. paru (Perciformes, Pomacanthidae)

Abstract

Several cytogenetical studies on marine Perciformes have demonstrated a conservative chromosomal pattern. Despite of some exceptions, even more specialized groups such as those from coral reefs have followed this trend. Nevertheless, the number of karyotypical information on fish from this environment is relatively reduced. In this work, cytogenetical data were obtained from two species of family Pomacanthidae (Perciformes), widespread throughout the Brazilian coast and associated to reefs: Pomacanthus paru and P. arcuatus. Both species have the same chromosomal constitution. The respective karyotypes are composed by one subtelocentric pair and 23 acrocentric pairs (2n=48). Single NORs are located on short arms of the subtelocentric pair. Heterochromatic blocks are restricted to centromeres and NORs. An accentuated NOR size heteromorphism between homologous was detected and analyses by chromomycin A3 demonstrated that it can be attributed to structural chromosome differences. A model of NOR evolution in Pomacanthus is proposed by pericentric inversion. Finally, the high level of resemblance between karyotypes from both species indicates their close phylogenetic relationship and diverges, although slightly, from the cytogenetical pattern so far described for Pomacanthidae representatives. © 2002 Taylor and Francis Group, LLC.