Jaw muscles and suspensoria in the Aplochitonidae (Teleostei: Salmoniformes) and their possible phylogenetic significance

Abstract

Recent studies question the monophyly of the family Aplochitonidae (Aplochiton + Lovettia). This issue is important partly because of the biogeographic hypothesis required to explain the disjunct distribution of these two genera if the family is monophyletic-Aplochiton is endemic to southernmost South America and Lovettia is restricted to Tasmania. Aplochiton and Lovettia were examined as part of a larger study on the suspensorium and its muscles in the lower teleosts. This paper describes in detail, for the first time, the jaw muscles and suspensoria in Aplochiton and Lovettia. These taxa share a number of features suggesting that they may form a clade, including a ligament extending from the posterolateral surface of the angulo-articular to the maxilla and a similar adductor mandibulae. Begle's conclusion that the family is paraphyletic is assessed and found to be unsound because of poorly defined characters.