Phylogenetic analysis of Dercetidae (Teleostei, Aulopiformes)

Abstract

The family Dercetidae comprises marine long snouted teleosts with elongated and shallow body, bearing one or more rows of tripartite scutes along the flanks and one or two pairs of prominent transverse processes on each abdominal vertebral centrum. It is commonly found in Tethyan deposits from Europe, Asia, Africa, South America and Central America, ranging from the Late Cretaceous (Cenomanian) to the Paleocene (Danian). The phylogenetic position of the group is controverse. Since 1960’s, it has been included within different orders (e.g., Myctophiformes, Salmoniformes, Stomiiformes, and Aulopiformes). In all cases, the authors only used non-numerical methods in the phylogenetic reconstructions. A parsimony analysis was carried out using the computer programs Hennig86 and PAUP* 4.0b10, based on a data matrix built with 52 non-ordered characters and seven terminals for ingroup (i.e., Cyranichthys, Dercetis, Dercetoides, Hastichthys, Pelargorhynchus, Rhynchodercetis, and new dercetid of the Pelotas Basin). The rooting was made using as outgroup the taxa Ichthyotringa, Apateopholis, Cimolichthys, Eurypholis, Saurorhamphus, and Prionolepis. Using exact algorithms, only one tree was obtained with 126 steps, consistency index of 0.50, and retention index of 0.54. This analysis revealed that Dercetidae is a monophyletic group supported by two synapomorphies: reduced neural spine and absence of longitudinal opercular crest. The topology founded was: (Dercetis + (Pelargorhynchus + (new dercetid + Cyranichthys)) + (Dercetoides + (Hastichthys + Rhynchodercetis))).