Posicionamento filogenético de Chaetognatha baseado em dados morfológicos

Abstract

The evolutionary affinities of Chaetognatha were tested under phylogenetic methods and the phylogeny of Deuterostomia was reconstructed. Deuterostomia + Chaetognatha formed the ingroup and Ectoprocta, Brachiopoda, Pterobranchia, Echinodermata, Enteropneusta, Tunicata, Cephalochordata, and Craniata were the terminal taxa, in addition to Chaetognatha. Oweniida, Pogonophora (Frenulata + Vestimentifera), and Phoronida formed the outgroup. The general anatomy of the group was analyzed and, from this process, the most informative characters were selected from the primary literature. The primary homology hypotheses were firstly built and subsequently tested with an appropriate congruence test, the parcimony in this case. Twenty five characters were selected, seventeen are multistate and eight are binary. The character matrix construction and the parcimony analysis were performed with the TNT 1.1 package. All characters were treated how unordered and received identical weights. Just one most parcimonious tree was recovered (length 59, consistence index 0.91 and retention index 0.90). The deuterostome monophyly, plus Chaetognatha, Ectoprocta and Brachiopoda, was recovered. Chaetognatha was recovered most closely related to Craniata, in a terminal position into the cladogram, supported by the characters 082, 16, 202 e 213 e 251 from the Table 4.