CONICET | Buscador de Institutos y Recursos Humanos

The species of the genus Percichthys (Percichthyidae) are endemic to southern South America and some authors pointed out that the genus includes four valid species based on the morphology of the head, jaws, and fins. A phylogenetic analysis suggests that three of them are morphotypes belonging to the same species, Percichthys trucha. The aim of this study is to describe for the first time the morphology of the cephalic seismosensory system of the Percichthys species complex, and its variability in the three morphotypes, in order to provide morphological elements that help to analyze the taxonomy of the Percichthys species complex. Comparisons of the cephalic seismosensory system between juveniles and adults were also conducted. Juvenile and adult specimens were collected in Argentinean Patagonia. The specimens were bleached in 5% H2O2 and the cephalic lateral line canal systems were filled with hematoxylin. Specimens were deposited in the Museo Argentino de Ciencias Naturales Bernardino Rivadavia, Argentina. The cephalic lateral line of the studied specimens is a widened type of canal system, is not connected to the trunk lateral line, and consists of preopercular-mandibular canal, infraorbital canal, supraorbital canal, temporal canal, supratemporal canal, and a supraorbital commisure. The number of pores increases during the ontogeny, while their diameters decrease. The number, position and size of infraorbital canal pores showed significant differences among morphotypes and juveniles. The interpopulation variation regarding the number, position, and size of pores is characteristic of an ongoing process of speciation because of the adaptation to different enviromental conditions. Our study contributes to the knowledge of the morphology of percichthids and describes for the first time the seismosensory system of the temperate perches.