Pores of the cephalic laterosensory system of Ostariophysi (Teleostei): an in-group and out-group analysis

Abstract

The lateral line sensory system of fishes is responsible, among other functions, for the perception of water movement and vibration. The functional unit of this system is the neuromast, which can be present on the skin surface or in grooves on it, or also in canals that are distributed along dermic bones, reaching the skin surface by pores. The ossification pattern related to the laterosensory canals is conserved among distinct fish lineages so that this morphological complex may represent a rich source of phylogenetic information. This system has been extensively used in cladistics analysis on several Ostariophysans, such as in Siluriformes. However, the laterosensory system of Characiformes, one of the most diverse order of teleost and also a member of the superorder Ostariophysi, has not been described in details yet, and its phylogenetic implications are poorly investigated. The present study mainly aims to carry out an exploratory analysis of the lateral line system on 1) the African families of Characiformes which are rare on Brazilian collections; 2) all lineages of Ostariophysi , specifically Cypriniformes and Gonorynchiformes, which are orders that do not naturally occur at Brazilian drainages; 3) non-Ostariophysan lineages of teleosts that are often closely related to Ostariophysi. For that, cleared and stained representatives of these taxa are going to be analyzed, and descriptions of the laterosensory system for each one will be provided. It is expected that these data may help to elucidate the phylogenetic relationships of these groups as well as in understanding of evolution of this morphological complex along the Ostariophysi evolution. (AU)