Análise comparativa da musculatura dorsolateral cefálica das espécies do grupo calophysus (Stewart, 1986) (siluriformes: pimelodidae)

Abstract

Pimelodidae have about 110 valid species, distributed in the Neotropical region in all continental environmental environments. The Calophysus group was described by Stewart in 1986, comprising the genera: Calophysus, Pinirampus, Pimelodina, Aguarunichthys and Luciopimelodus. Later molecular studies supported the monophyly of the Calophysus group and proposed the group with Megalonema and Cheirocerus as your sister group. The Calophysus group presents as a synapomorphies the partial or total encapsulation of an extension of the swim bladder within the transverse processes of the fourth vertebra. In the present work, the musculature of Calophysus macropterus, Pinirampus pirinampu, Megalonema platycephalum, Cheirocerus goeldii, Luciopimelodus pati, Pimelodina flavipinnis; the outgroup was composed by Propimelodus eigenmanni, Pimelodus blochii, Pimelodus ornatus and as root Pseudopimelodus aff buffonius. To carry out the study on the dorsolateral cephalic musculature of the species of the genera of the Calophysus group, the protocol was followed using Alizarin, Alcian Blue, ethyl alcohol and glacial acetic acid, for the staining of bones and cartilage, then removed. if the skin for the observation and description of the muscles. The organization of the characters was done in Mesquite and the analysis in TNT. Five main external muscles that make up the dorsolateral cephalic musculature were observed. Extensor tentaculi muscle with rectangular shape and has two or three subsections, which are responsible for the movement of the maxillary barbel, being exclusively present in catfish. Adductor mandibulae, segmentum facialis not showing clear differentiations in adductor mandibulae, pars rictalis, pars malaris. The levator arcus palatini muscle has a trapezoidal shape, promoting the connection of the neurocranium to the suspensory. Two muscles are responsible for moving the operculum: the triangular-shaped levator operculi, and the dilatator operculi with a more rectangular arrangement, presenting its sections. The results were based on 13 characters selected from descriptive analyzes of the species of the Calophysus group, thus suggesting that the adductor mandibulae and extensor tentaculi muscles are the muscles that most varied among the species seen in the present work, becoming phylogenetically more informative. The largest number of characters that point to plesiomorphies for the species of the root group were in the levator arcus palatini and adductor mandibulae muscles, while the other muscles described differ in sizes, insertions and shapes among the species of the Calophysus group, accentuated by the anatomical differences between the head sizes and shapes. Keywords: Comparative anatomy; Catfish; Phylogeny; Myology; Musculature