Canais e poros do sistema laterossensorial cefálico em Callichthyidae (Ostariophysi: Siluriformes: Loricarioidea): anatomia comparada, sinonímia e implicações gilogenéticas

Abstract

The lateral line mechanoreceptor system is typically composed of a series of neuromast contained in canals that are connected via pores and traverse dermal bones of the head. This system is an important sensory modality in most stages of fishes life history because it allows organisms to detect changes in water flow sites and weak electric fields. The lateral line canals system may vary significantly in different species of fishes, even in closely related species. Such variability includes the presence or absence of pores and canals, as well as the number, location, branching and width of the canals, as well as the number, size and location of the pores in the canal. Callichthyidae is the third most diverse family within Loricarioidea (Siluriformes), allocating 220 valid species, being easily recognized for having the body almost completely protected by bony plates, basically arranged in two longitudinal series. It is currently subdivided into two subfamilies: Callichthyinae and Corydoradinae and has been used in studies of the lateral line system since the 19 century, and characters referring to this system are used as a diagnosis among recently described species. However, the group lacks homology assessments of the canals and pores of the cephalic laterosensory system. The aim of the present work is to investigate the characters related to the cephalic laterosensory system of Callichthyidae through describing the comparative anatomy between the taxa and postulate about the homology of this system in order to reconstruct the characters within the group in a combined matrix analysis of morphological and molecular data. In addition, a review and redefinition of the anatomical nomenclature used for laterosensory canals and pores in the family was performed. In this study, 31 characters were validated and 4 synapomorphies were found for Callichthyidae, as well their respective lineages, evidencing the importance of investigation of characters of morphological complex not traditionally used. The present study also shows that once combined with other morphological data, they reflect greater consistency and resolution in both a phylogenetical and taxonomical context.