Redescrição osteológica craniana de 4 espécies de Polypteriformes (Actinopterygii: Cladistia), com observações nas diferenças morfológicas de pínulas

Abstract

Polypteriformes is a basal group of Actinopterygii easily recognized by its elongated body, dorsal fin composed of 5 to 18 finlets, presence of gular plates, presence of ganoid scales, lung, upperjaw fixed to neurocranium and four gill arcs. This group is composed by 14 living species, all restricted to continental African waters. The aims of this study are: to redescribe the cranial osteology of 4 species of the Polypteridae family, to analyze the morphological differences of the finlets to test intra and interspecific variation and validate the diagnostic characters for taxonomy and systematics and to test protocols of DNA extraction in samples of a species of polypteriformes, with the goal to propose, in the future, the use of the same protocol in a phylogenetic study. Due to the large intraspecific numerical variations, extrascapulars and bones of the spiracular series were inefficient to separate taxa. The species of this study can be separated by the following characters: presence of dermosphenotic and dermohyal in P. senegalus, fusion of the dermosphenotic with frontal allied to the presence of dermohyal in P. delhezi, gular plates connecting only in their anterior portion allied with the absence of dermohyal in P. palmas, and the gular plates do not connect medially allied with the absence of subopercle in E. Calabaricus. Analysis of all the other species in the group is needed to confirm that the diagnostic characters suggested to the 4 species described here also separate them from the other species. Polypteriformes finlets do not have identical morphology in the same individual, which doubts the identification of fossil pinnulae, thus making necessary a revision of the previously proposed fossil species, as well as a morphometric study that characterizes the pinnulae of extant species. Finally, the 'salting-out' extraction protocol attested efficient for extracting DNA from Polypteridae samples, and will probably be applied in future phylogenetic studies on Polypteriformes.