Comparative study of the musculature associated to feeding between the guitarfishes Rhinobatos percellens and Zapteryx brevirostris (Chondrichthyes, Rhinobatidae)

Abstract

The present study intend to describe and compare the musculature associate to the feeding mechanism of two southern Brazilian guitarfishes species, Rhinobatos percellens and Zapteryx brevirostris. The biological material will be provided by artisanal and industrial fishery, and information regarding sex, total leght and width of disc will be recorded. The anterior region of the disc of the specimens will be removed with a incision below the pectoral girdle. The specimens will be dissecated describing the musculature concerning the relative size, locals of origin and insertion, and ilustrative plates will be done. The muscles that will be described are: epaxialis, quadratomandibularis, preorbitalis, levator palatoquadrati, depressor mandibularis, levator hyomandibularis, depressor hyomandibularis, levator rostri, coracomandibularis, coracohyoideus, coracohyomandibularis, all of then involved in feeding activities. The muscles will be compared then between the species and sexual and ontogenetic changes will be investigated pertaining to each species, aiming the search of possible distinct standards of these species from Rhinobatidae family.